stb_vorbis.h

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#ifndef STB_VORBIS_INCLUDE_STB_VORBIS_H
#define STB_VORBIS_INCLUDE_STB_VORBIS_H

#include <assert.h>

#ifdef __cplusplus
extern "C" {
#endif

typedef struct
{
 char *alloc_buffer;
 int alloc_buffer_length_in_bytes;
} stb_vorbis_alloc;


/* FUNCTIONS USEABLE WITH ALL INPUT MODES */

typedef struct stb_vorbis stb_vorbis;

typedef struct
{
 unsigned int sample_rate;
 int channels;

 unsigned int setup_memory_required;
 unsigned int setup_temp_memory_required;
 unsigned int temp_memory_required;

 int max_frame_size;
} stb_vorbis_info;

/* get general information about the file */
extern stb_vorbis_info stb_vorbis_get_info(stb_vorbis *f);

/* get the last error detected (clears it, too) */
extern int stb_vorbis_get_error(stb_vorbis *f);

/* close an ogg vorbis file and free all memory in use */
extern void stb_vorbis_close(stb_vorbis *f);

/* this function returns the offset (in samples) from the beginning of the
 * file that will be returned by the next decode, if it is known, or -1
 * otherwise. after a flush_pushdata() call, this may take a while before
 * it becomes valid again.
 * NOT WORKING YET after a seek with PULLDATA API */
extern int stb_vorbis_get_sample_offset(stb_vorbis *f);

/* returns the current seek point within the file, or offset from the beginning
 * of the memory buffer. In pushdata mode it returns 0. */
extern unsigned int stb_vorbis_get_file_offset(stb_vorbis *f);

/* PULLING INPUT API */

#ifndef STB_VORBIS_NO_PULLDATA_API
/* This API assumes stb_vorbis is allowed to pull data from a source--
 * either a block of memory containing the _entire_ vorbis stream, or a
 * FILE * that you or it create, or possibly some other reading mechanism
 * if you go modify the source to replace the FILE * case with some kind
 * of callback to your code. (But if you don't support seeking, you may
 * just want to go ahead and use pushdata.) */

extern stb_vorbis * stb_vorbis_open_memory(const unsigned char *data, int len,
 int *error, stb_vorbis_alloc *alloc_buffer);
/* create an ogg vorbis decoder from an ogg vorbis stream in memory (note
 * this must be the entire stream!). on failure, returns NULL and sets *error */

extern int stb_vorbis_seek_frame(stb_vorbis *f, unsigned int sample_number);
extern int stb_vorbis_seek(stb_vorbis *f, unsigned int sample_number);
/* NOT WORKING YET
 * these functions seek in the Vorbis file to (approximately) 'sample_number'.
 * after calling seek_frame(), the next call to get_frame_*() will include
 * the specified sample. after calling stb_vorbis_seek(), the next call to
 * stb_vorbis_get_samples_* will start with the specified sample. If you
 * do not need to seek to EXACTLY the target sample when using get_samples_*,
 * you can also use seek_frame(). */

extern void stb_vorbis_seek_start(stb_vorbis *f);
/* this function is equivalent to stb_vorbis_seek(f,0), but it
 * actually works */

extern unsigned int stb_vorbis_stream_length_in_samples(stb_vorbis *f);
extern float stb_vorbis_stream_length_in_seconds(stb_vorbis *f);
/* these functions return the total length of the vorbis stream */

extern int stb_vorbis_get_frame_float(stb_vorbis *f, int *channels, float ***output);
/* decode the next frame and return the number of samples. the number of
 * channels returned are stored in *channels (which can be NULL--it is always
 * the same as the number of channels reported by get_info). *output will
 * contain an array of float* buffers, one per channel. These outputs will
 * be overwritten on the next call to stb_vorbis_get_frame_*.
 *
 * You generally should not intermix calls to stb_vorbis_get_frame_*()
 * and stb_vorbis_get_samples_*(), since the latter calls the former.
 */

extern int stb_vorbis_get_samples_float_interleaved(stb_vorbis *f, int channels, float *buffer, int num_floats);
extern int stb_vorbis_get_samples_float(stb_vorbis *f, int channels, float **buffer, int num_samples);
/* gets num_samples samples, not necessarily on a frame boundary--this requires
 * buffering so you have to supply the buffers. DOES NOT APPLY THE COERCION RULES.
 * Returns the number of samples stored per channel; it may be less than requested
 * at the end of the file. If there are no more samples in the file, returns 0.
 */

#endif

/* ERROR CODES */

enum STBVorbisError
{
 VORBIS__no_error,

 VORBIS_need_more_data=1, /* not a real error */

 VORBIS_invalid_api_mixing, /* can't mix API modes */
 VORBIS_outofmem, /* not enough memory */
 VORBIS_feature_not_supported, /* uses floor 0 */
 VORBIS_too_many_channels, /* STB_VORBIS_MAX_CHANNELS is too small */
 VORBIS_file_open_failure, /* fopen() failed */
 VORBIS_seek_without_length, /* can't seek in unknown-length file */

 VORBIS_unexpected_eof=10, /* file is truncated? */
 VORBIS_seek_invalid, /* seek past EOF */

 /* decoding errors (corrupt/invalid stream) -- you probably
 * don't care about the exact details of these */

 /* vorbis errors: */
 VORBIS_invalid_setup=20,
 VORBIS_invalid_stream,

 /* ogg errors: */
 VORBIS_missing_capture_pattern=30,
 VORBIS_invalid_stream_structure_version,
 VORBIS_continued_packet_flag_invalid,
 VORBIS_incorrect_stream_serial_number,
 VORBIS_invalid_first_page,
 VORBIS_bad_packet_type,
 VORBIS_cant_find_last_page,
 VORBIS_seek_failed
};


#ifdef __cplusplus
}
#endif

#endif /* STB_VORBIS_INCLUDE_STB_VORBIS_H */

#ifndef STB_VORBIS_HEADER_ONLY

/* global configuration settings (e.g. set these in the project/makefile),
 * or just set them in this file at the top (although ideally the first few
 * should be visible when the header file is compiled too, although it's not
 * crucial)
 */

/* STB_VORBIS_NO_PULLDATA_API
 * does not compile the code for the non-pushdata APIs
 */
#if 0
#define STB_VORBIS_NO_PULLDATA_API
#endif

/* STB_VORBIS_MAX_CHANNELS [number]
 * globally define this to the maximum number of channels you need.
 * The spec does not put a restriction on channels except that
 * the count is stored in a byte, so 255 is the hard limit.
 * Reducing this saves about 16 bytes per value, so using 16 saves
 * (255-16)*16 or around 4KB. Plus anything other memory usage
 * I forgot to account for. Can probably go as low as 8 (7.1 audio),
 * 6 (5.1 audio), or 2 (stereo only).
 */
#ifndef STB_VORBIS_MAX_CHANNELS
#define STB_VORBIS_MAX_CHANNELS 16 /* enough for anyone? */
#endif

/* STB_VORBIS_FAST_HUFFMAN_LENGTH [number]
 * sets the log size of the huffman-acceleration table. Maximum
 * supported value is 24. with larger numbers, more decodings are O(1),
 * but the table size is larger so worse cache missing, so you'll have
 * to probe (and try multiple ogg vorbis files) to find the sweet spot.
 */
#ifndef STB_VORBIS_FAST_HUFFMAN_LENGTH
#define STB_VORBIS_FAST_HUFFMAN_LENGTH 10
#endif

/* STB_VORBIS_FAST_BINARY_LENGTH [number]
 * sets the log size of the binary-search acceleration table. this
 * is used in similar fashion to the fast-huffman size to set initial
 * parameters for the binary search

 * STB_VORBIS_FAST_HUFFMAN_INT
 * The fast huffman tables are much more efficient if they can be
 * stored as 16-bit results instead of 32-bit results. This restricts
 * the codebooks to having only 65535 possible outcomes, though.
 * (At least, accelerated by the huffman table.)
 */
#ifndef STB_VORBIS_FAST_HUFFMAN_INT
#define STB_VORBIS_FAST_HUFFMAN_SHORT
#endif

/* STB_VORBIS_NO_HUFFMAN_BINARY_SEARCH
 * If the 'fast huffman' search doesn't succeed, then stb_vorbis falls
 * back on binary searching for the correct one. This requires storing
 * extra tables with the huffman codes in sorted order. Defining this
 * symbol trades off space for speed by forcing a linear search in the
 * non-fast case, except for "sparse" codebooks.
 */
#if 0
#define STB_VORBIS_NO_HUFFMAN_BINARY_SEARCH
#endif

/* STB_VORBIS_CODEBOOK_SHORTS
 * The vorbis file format encodes VQ codebook floats as ax+b where a and
 * b are floating point per-codebook constants, and x is a 16-bit int.
 * Normally, stb_vorbis decodes them to floats rather than leaving them
 * as 16-bit ints and computing ax+b while decoding. This is a speed/space
 * tradeoff; you can save space by defining this flag.
 */
#ifndef STB_VORBIS_CODEBOOK_SHORTS
#define STB_VORBIS_CODEBOOK_FLOATS
#endif

#include <retro_inline.h>

#define MAX_BLOCKSIZE_LOG 13 /* from specification */
#define MAX_BLOCKSIZE (1 << MAX_BLOCKSIZE_LOG)

#ifndef TRUE
#define TRUE 1
#define FALSE 0
#endif

#ifdef STB_VORBIS_CODEBOOK_FLOATS
typedef float stb_vorbis_codetype;
#else
typedef uint16_t stb_vorbis_codetype;
#endif

/* @NOTE
 *
 * Some arrays below are tagged "//varies", which means it's actually
 * a variable-sized piece of data, but rather than malloc I assume it's
 * small enough it's better to just allocate it all together with the
 * main thing
 *
 * Most of the variables are specified with the smallest size I could pack
 * them into. It might give better performance to make them all full-sized
 * integers. It should be safe to freely rearrange the structures or change
 * the sizes larger--nothing relies on silently truncating etc., nor the
 * order of variables.
 */

#define FAST_HUFFMAN_TABLE_SIZE (1 << STB_VORBIS_FAST_HUFFMAN_LENGTH)
#define FAST_HUFFMAN_TABLE_MASK (FAST_HUFFMAN_TABLE_SIZE - 1)

typedef struct
{
 int dimensions, entries;
 uint8_t *codeword_lengths;
 float minimum_value;
 float delta_value;
 uint8_t value_bits;
 uint8_t lookup_type;
 uint8_t sequence_p;
 uint8_t sparse;
 uint32_t lookup_values;
 stb_vorbis_codetype *multiplicands;
 uint32_t *codewords;
 #ifdef STB_VORBIS_FAST_HUFFMAN_SHORT
 int16_t fast_huffman[FAST_HUFFMAN_TABLE_SIZE];
 #else
 int32_t fast_huffman[FAST_HUFFMAN_TABLE_SIZE];
 #endif
 uint32_t *sorted_codewords;
 int *sorted_values;
 int sorted_entries;
} Codebook;

typedef struct
{
 uint8_t order;
 uint16_t rate;
 uint16_t bark_map_size;
 uint8_t amplitude_bits;
 uint8_t amplitude_offset;
 uint8_t number_of_books;
 uint8_t book_list[16]; /* varies */
} Floor0;

typedef struct
{
 uint8_t partitions;
 uint8_t partition_class_list[32]; /* varies */
 uint8_t class_dimensions[16]; /* varies */
 uint8_t class_subclasses[16]; /* varies */
 uint8_t class_masterbooks[16]; /* varies */
 int16_t subclass_books[16][8]; /* varies */
 uint16_t Xlist[31*8+2]; /* varies */
 uint8_t sorted_order[31*8+2];
 uint8_t neighbors[31*8+2][2];
 uint8_t floor1_multiplier;
 uint8_t rangebits;
 int values;
} Floor1;

typedef union
{
 Floor0 floor0;
 Floor1 floor1;
} Floor;

typedef struct
{
 uint32_t begin, end;
 uint32_t part_size;
 uint8_t classifications;
 uint8_t classbook;
 uint8_t **classdata;
 int16_t (*residue_books)[8];
} Residue;

typedef struct
{
 uint8_t magnitude;
 uint8_t angle;
 uint8_t mux;
} MappingChannel;

typedef struct
{
 uint16_t coupling_steps;
 MappingChannel *chan;
 uint8_t submaps;
 uint8_t submap_floor[15]; /* varies */
 uint8_t submap_residue[15]; /* varies */
} Mapping;

typedef struct
{
 uint8_t blockflag;
 uint8_t mapping;
 uint16_t windowtype;
 uint16_t transformtype;
} Mode;

typedef struct
{
 uint32_t goal_crc; /* expected crc if match */
 int bytes_left; /* bytes left in packet */
 uint32_t crc_so_far; /* running crc */
 int bytes_done; /* bytes processed in _current_ chunk */
 uint32_t sample_loc; /* granule pos encoded in page */
} CRCscan;

typedef struct
{
 uint32_t page_start, page_end;
 uint32_t after_previous_page_start;
 uint32_t first_decoded_sample;
 uint32_t last_decoded_sample;
} ProbedPage;

struct stb_vorbis
{
 /* user-accessible info */
 unsigned int sample_rate;
 int channels;

 unsigned int setup_memory_required;
 unsigned int temp_memory_required;
 unsigned int setup_temp_memory_required;

 uint8_t *stream;
 uint8_t *stream_start;
 uint8_t *stream_end;

 uint32_t stream_len;

 uint8_t push_mode;

 uint32_t first_audio_page_offset;

 ProbedPage p_first, p_last;

 /* memory management */
 stb_vorbis_alloc alloc;
 int setup_offset;
 int temp_offset;

 /* run-time results */
 int eof;
 enum STBVorbisError error;

 /* user-useful data */

 /* header info */
 int blocksize[2];
 int blocksize_0, blocksize_1;
 int codebook_count;
 Codebook *codebooks;
 int floor_count;
 uint16_t floor_types[64]; /* varies */
 Floor *floor_config;
 int residue_count;
 uint16_t residue_types[64]; /* varies */
 Residue *residue_config;
 int mapping_count;
 Mapping *mapping;
 int mode_count;
 Mode mode_config[64]; /* varies */

 uint32_t total_samples;

 /* decode buffer */
 float *channel_buffers[STB_VORBIS_MAX_CHANNELS];
 float *outputs [STB_VORBIS_MAX_CHANNELS];

 float *previous_window[STB_VORBIS_MAX_CHANNELS];
 int previous_length;

 int16_t *finalY[STB_VORBIS_MAX_CHANNELS];

 uint32_t current_loc; /* sample location of next frame to decode */
 int current_loc_valid;

 /* per-blocksize precomputed data */

 /* twiddle factors */
 float *A[2],*B[2],*C[2];
 float *window[2];
 uint16_t *bit_reverse[2];

 /* current page/packet/segment streaming info */
 uint32_t serial; /* stream serial number for verification */
 int last_page;
 int segment_count;
 uint8_t segments[255];
 uint8_t page_flag;
 uint8_t bytes_in_seg;
 uint8_t first_decode;
 int next_seg;
 int last_seg; /* flag that we're on the last segment */
 int last_seg_which; /* what was the segment number of the last seg? */
 uint32_t acc;
 int valid_bits;
 int packet_bytes;
 int end_seg_with_known_loc;
 uint32_t known_loc_for_packet;
 int discard_samples_deferred;
 uint32_t samples_output;

 /* push mode scanning */
 int page_crc_tests; /* only in push_mode: number of tests active; -1 if not searching */

 /* sample-access */
 int channel_buffer_start;
 int channel_buffer_end;
};

#define IS_PUSH_MODE(f) FALSE

typedef struct stb_vorbis vorb;

static int error(vorb *f, enum STBVorbisError e)
{
 f->error = e;
 if (!f->eof && e != VORBIS_need_more_data) {
 f->error=e; /* breakpoint for debugging */
 }
 return 0;
}


/* these functions are used for allocating temporary memory
 * while decoding. if you can afford the stack space, use
 * alloca(); otherwise, provide a temp buffer and it will
 * allocate out of those.
 */

#define array_size_required(count,size) (count*(sizeof(void *)+(size)))

#define temp_alloc(f,size) (f->alloc.alloc_buffer ? setup_temp_malloc(f,size) : alloca(size))
#define temp_alloc_save(f) ((f)->temp_offset)
#define temp_alloc_restore(f,p) ((f)->temp_offset = (p))

#define temp_block_array(f,count,size) make_block_array(temp_alloc(f,array_size_required(count,size)), count, size)

/* given a sufficiently large block of memory, make an array of pointers to subblocks of it */
static void *make_block_array(void *mem, int count, int size)
{
 int i;
 void ** p = (void **) mem;
 char *q = (char *) (p + count);
 for (i=0; i < count; ++i) {
 p[i] = q;
 q += size;
 }
 return p;
}

static void *setup_malloc(vorb *f, int sz)
{
 sz = (sz+3) & ~3;
 f->setup_memory_required += sz;
 if (f->alloc.alloc_buffer) {
 void *p = (char *) f->alloc.alloc_buffer + f->setup_offset;
 if (f->setup_offset + sz > f->temp_offset) return NULL;
 f->setup_offset += sz;
 return p;
 }
 return sz ? malloc(sz) : NULL;
}

static void setup_free(vorb *f, void *p)
{
 if (f->alloc.alloc_buffer) return; /* do nothing; setup mem is not a stack */
 free(p);
}

static void *setup_temp_malloc(vorb *f, int sz)
{
 sz = (sz+3) & ~3;
 if (f->alloc.alloc_buffer) {
 if (f->temp_offset - sz < f->setup_offset) return NULL;
 f->temp_offset -= sz;
 return (char *) f->alloc.alloc_buffer + f->temp_offset;
 }
 return malloc(sz);
}

static void setup_temp_free(vorb *f, void *p, int sz)
{
 if (f->alloc.alloc_buffer) {
 f->temp_offset += (sz+3)&~3;
 return;
 }
 free(p);
}

#define CRC32_POLY 0x04c11db7 /* from spec */

static uint32_t stb_vorbis_crc_table[256];
static void crc32_init(void)
{
 int i,j;
 uint32_t s;
 for(i=0; i < 256; i++) {
 for (s=i<<24, j=0; j < 8; ++j)
 s = (s << 1) ^ (s >= (1U<<31) ? CRC32_POLY : 0);
 stb_vorbis_crc_table[i] = s;
 }
}

static INLINE uint32_t crc32_update(uint32_t crc, uint8_t byte)
{
 return (crc << 8) ^ stb_vorbis_crc_table[byte ^ (crc >> 24)];
}

/* used in setup, and for huffman that doesn't go fast path */
static unsigned int bit_reverse(unsigned int n)
{
 n = ((n & 0xAAAAAAAA) >> 1) | ((n & 0x55555555) << 1);
 n = ((n & 0xCCCCCCCC) >> 2) | ((n & 0x33333333) << 2);
 n = ((n & 0xF0F0F0F0) >> 4) | ((n & 0x0F0F0F0F) << 4);
 n = ((n & 0xFF00FF00) >> 8) | ((n & 0x00FF00FF) << 8);
 return (n >> 16) | (n << 16);
}

static float square(float x)
{
 return x*x;
}

/* this is a weird definition of log2() for which log2(1) = 1, log2(2) = 2, log2(4) = 3
 * as required by the specification. fast(?) implementation from stb.h
 * @OPTIMIZE: called multiple times per-packet with "constants"; move to setup
 */
static int ilog(int32_t n)
{
 static signed char log2_4[16] = { 0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4 };

 /* 2 compares if n < 16, 3 compares otherwise (4 if signed or n > 1<<29) */
 if (n < (1 << 14))
 if (n < (1 << 4)) return 0 + log2_4[n ];
 else if (n < (1 << 9)) return 5 + log2_4[n >> 5];
 else return 10 + log2_4[n >> 10];
 else if (n < (1 << 24))
 if (n < (1 << 19)) return 15 + log2_4[n >> 15];
 else return 20 + log2_4[n >> 20];
 else if (n < (1 << 29)) return 25 + log2_4[n >> 25];
 else if (n < (1 << 31)) return 30 + log2_4[n >> 30];
 else return 0; /* signed n returns 0 */
}

#ifndef M_PI
 #define M_PI 3.14159265358979323846264f /* from CRC */
#endif

/* code length assigned to a value with no huffman encoding */
#define NO_CODE 255

/* LEAF SETUP FUNCTIONS */

/* these functions are only called at setup, and only a few times
 * per file */

static float float32_unpack(uint32_t x)
{
 /* from the specification */
 uint32_t mantissa = x & 0x1fffff;
 uint32_t sign = x & 0x80000000;
 uint32_t exp = (x & 0x7fe00000) >> 21;
 double res = sign ? -(double)mantissa : (double)mantissa;
 return (float) ldexp((float)res, exp-788);
}


/* zlib & jpeg huffman tables assume that the output symbols
 * can either be arbitrarily arranged, or have monotonically
 * increasing frequencies--they rely on the lengths being sorted;
 * this makes for a very simple generation algorithm.
 * vorbis allows a huffman table with non-sorted lengths. This
 * requires a more sophisticated construction, since symbols in
 * order do not map to huffman codes "in order".
 */
static void add_entry(Codebook *c, uint32_t huff_code, int symbol, int count, int len, uint32_t *values)
{
 if (!c->sparse) {
 c->codewords [symbol] = huff_code;
 } else {
 c->codewords [count] = huff_code;
 c->codeword_lengths[count] = len;
 values [count] = symbol;
 }
}

static int compute_codewords(Codebook *c, uint8_t *len, int n, uint32_t *values)
{
 int i,k,m=0;
 uint32_t available[32];

 memset(available, 0, sizeof(available));
 /* find the first entry */
 for (k=0; k < n; ++k) if (len[k] < NO_CODE) break;
 if (k == n) { assert(c->sorted_entries == 0); return TRUE; }
 /* add to the list */
 add_entry(c, 0, k, m++, len[k], values);
 /* add all available leaves */
 for (i=1; i <= len[k]; ++i)
 available[i] = 1 << (32-i);
 /* note that the above code treats the first case specially,
 * but it's really the same as the following code, so they
 * could probably be combined (except the initial code is 0,
 * and I use 0 in available[] to mean 'empty') */
 for (i=k+1; i < n; ++i) {
 uint32_t res;
 int z = len[i], y;
 if (z == NO_CODE) continue;
 /* find lowest available leaf (should always be earliest,
 * which is what the specification calls for)
 * note that this property, and the fact we can never have
 * more than one free leaf at a given level, isn't totally
 * trivial to prove, but it seems true and the assert never
 * fires, so! */
 while (z > 0 && !available[z]) --z;
 if (z == 0) { assert(0); return FALSE; }
 res = available[z];
 available[z] = 0;
 add_entry(c, bit_reverse(res), i, m++, len[i], values);
 /* propogate availability up the tree */
 if (z != len[i]) {
 for (y=len[i]; y > z; --y) {
 assert(available[y] == 0);
 available[y] = res + (1 << (32-y));
 }
 }
 }
 return TRUE;
}

/* accelerated huffman table allows fast O(1) match of all symbols
 * of length <= STB_VORBIS_FAST_HUFFMAN_LENGTH */
static void compute_accelerated_huffman(Codebook *c)
{
 int i, len;
 for (i=0; i < FAST_HUFFMAN_TABLE_SIZE; ++i)
 c->fast_huffman[i] = -1;

 len = c->sparse ? c->sorted_entries : c->entries;
 #ifdef STB_VORBIS_FAST_HUFFMAN_SHORT
 if (len > 32767) len = 32767; /* largest possible value we can encode! */
 #endif
 for (i=0; i < len; ++i) {
 if (c->codeword_lengths[i] <= STB_VORBIS_FAST_HUFFMAN_LENGTH) {
 uint32_t z = c->sparse ? bit_reverse(c->sorted_codewords[i]) : c->codewords[i];
 /* set table entries for all bit combinations in the higher bits */
 while (z < FAST_HUFFMAN_TABLE_SIZE) {
 c->fast_huffman[z] = i;
 z += 1 << c->codeword_lengths[i];
 }
 }
 }
}

#ifdef _MSC_VER
#define STBV_CDECL __cdecl
#else
#define STBV_CDECL
#endif

static int STBV_CDECL uint32_t_compare(const void *p, const void *q)
{
 uint32_t x = * (uint32_t *) p;
 uint32_t y = * (uint32_t *) q;
 return x < y ? -1 : x > y;
}

static int include_in_sort(Codebook *c, uint8_t len)
{
 if (c->sparse) { assert(len != NO_CODE); return TRUE; }
 if (len == NO_CODE) return FALSE;
 if (len > STB_VORBIS_FAST_HUFFMAN_LENGTH) return TRUE;
 return FALSE;
}

/* if the fast table above doesn't work, we want to binary
 * search them... need to reverse the bits */
static void compute_sorted_huffman(Codebook *c, uint8_t *lengths, uint32_t *values)
{
 int i, len;
 /* build a list of all the entries
 * OPTIMIZATION: don't include the short ones, since they'll be caught by FAST_HUFFMAN.
 * this is kind of a frivolous optimization--I don't see any performance improvement,
 * but it's like 4 extra lines of code, so. */
 if (!c->sparse) {
 int k = 0;
 for (i=0; i < c->entries; ++i)
 if (include_in_sort(c, lengths[i]))
 c->sorted_codewords[k++] = bit_reverse(c->codewords[i]);
 assert(k == c->sorted_entries);
 } else {
 for (i=0; i < c->sorted_entries; ++i)
 c->sorted_codewords[i] = bit_reverse(c->codewords[i]);
 }

 qsort(c->sorted_codewords, c->sorted_entries, sizeof(c->sorted_codewords[0]), uint32_t_compare);
 c->sorted_codewords[c->sorted_entries] = 0xffffffff;

 len = c->sparse ? c->sorted_entries : c->entries;
 /* now we need to indicate how they correspond; we could either
 * #1: sort a different data structure that says who they correspond to
 * #2: for each sorted entry, search the original list to find who corresponds
 * #3: for each original entry, find the sorted entry
 * #1 requires extra storage, #2 is slow, #3 can use binary search! */
 for (i=0; i < len; ++i) {
 int huff_len = c->sparse ? lengths[values[i]] : lengths[i];
 if (include_in_sort(c,huff_len)) {
 uint32_t code = bit_reverse(c->codewords[i]);
 int x=0, n=c->sorted_entries;
 while (n > 1) {
 /* invariant: sc[x] <= code < sc[x+n] */
 int m = x + (n >> 1);
 if (c->sorted_codewords[m] <= code) {
 x = m;
 n -= (n>>1);
 } else {
 n >>= 1;
 }
 }
 assert(c->sorted_codewords[x] == code);
 if (c->sparse) {
 c->sorted_values[x] = values[i];
 c->codeword_lengths[x] = huff_len;
 } else {
 c->sorted_values[x] = i;
 }
 }
 }
}

/* only run while parsing the header (3 times) */
static int vorbis_validate(uint8_t *data)
{
 static uint8_t vorbis[6] = { 'v', 'o', 'r', 'b', 'i', 's' };
 return memcmp(data, vorbis, 6) == 0;
}

/* called from setup only, once per code book
 * (formula implied by specification) */
static int lookup1_values(int entries, int dim)
{
 int r = (int) floor(exp((float) log((float) entries) / dim));
 if ((int) floor(pow((float) r+1, dim)) <= entries) /* (int) cast for MinGW warning; */
 ++r; /* floor() to avoid _ftol() when non-CRT */
 assert(pow((float) r+1, dim) > entries);
 assert((int) floor(pow((float) r, dim)) <= entries); /* (int),floor() as above */
 return r;
}

/* called twice per file */
static void compute_twiddle_factors(int n, float *A, float *B, float *C)
{
 int n4 = n >> 2, n8 = n >> 3;
 int k,k2;

 for (k=k2=0; k < n4; ++k,k2+=2) {
 A[k2 ] = (float) cos(4*k*M_PI/n);
 A[k2+1] = (float) -sin(4*k*M_PI/n);
 B[k2 ] = (float) cos((k2+1)*M_PI/n/2) * 0.5f;
 B[k2+1] = (float) sin((k2+1)*M_PI/n/2) * 0.5f;
 }
 for (k=k2=0; k < n8; ++k,k2+=2) {
 C[k2 ] = (float) cos(2*(k2+1)*M_PI/n);
 C[k2+1] = (float) -sin(2*(k2+1)*M_PI/n);
 }
}

static void compute_window(int n, float *window)
{
 int n2 = n >> 1, i;
 for (i=0; i < n2; ++i)
 window[i] = (float) sin(0.5 * M_PI * square((float) sin((i - 0 + 0.5) / n2 * 0.5 * M_PI)));
}

static void compute_bitreverse(int n, uint16_t *rev)
{
 int ld = ilog(n) - 1; /* ilog is off-by-one from normal definitions */
 int i, n8 = n >> 3;
 for (i=0; i < n8; ++i)
 rev[i] = (bit_reverse(i) >> (32-ld+3)) << 2;
}

static int init_blocksize(vorb *f, int b, int n)
{
 int n2 = n >> 1, n4 = n >> 2, n8 = n >> 3;
 f->A[b] = (float *) setup_malloc(f, sizeof(float) * n2);
 f->B[b] = (float *) setup_malloc(f, sizeof(float) * n2);
 f->C[b] = (float *) setup_malloc(f, sizeof(float) * n4);
 if (!f->A[b] || !f->B[b] || !f->C[b]) return error(f, VORBIS_outofmem);
 compute_twiddle_factors(n, f->A[b], f->B[b], f->C[b]);
 f->window[b] = (float *) setup_malloc(f, sizeof(float) * n2);
 if (!f->window[b]) return error(f, VORBIS_outofmem);
 compute_window(n, f->window[b]);
 f->bit_reverse[b] = (uint16_t *) setup_malloc(f, sizeof(uint16_t) * n8);
 if (!f->bit_reverse[b]) return error(f, VORBIS_outofmem);
 compute_bitreverse(n, f->bit_reverse[b]);
 return TRUE;
}

static void neighbors(uint16_t *x, int n, int *plow, int *phigh)
{
 int low = -1;
 int high = 65536;
 int i;
 for (i=0; i < n; ++i) {
 if (x[i] > low && x[i] < x[n]) { *plow = i; low = x[i]; }
 if (x[i] < high && x[i] > x[n]) { *phigh = i; high = x[i]; }
 }
}

/* this has been repurposed so y is now the original index instead of y */
typedef struct
{
 uint16_t x,y;
} STBV_Point;

static int STBV_CDECL point_compare(const void *p, const void *q)
{
 STBV_Point *a = (STBV_Point *) p;
 STBV_Point *b = (STBV_Point *) q;
 return a->x < b->x ? -1 : a->x > b->x;
}

/* END LEAF SETUP FUNCTIONS */

static uint8_t get8(vorb *z)
{
 if (z->stream >= z->stream_end) { z->eof = TRUE; return 0; }
 return *z->stream++;
}

static uint32_t get32(vorb *f)
{
 uint32_t x;
 x = get8(f);
 x += get8(f) << 8;
 x += get8(f) << 16;
 x += get8(f) << 24;
 return x;
}

static int getn(vorb *z, uint8_t *data, int n)
{
 if (z->stream+n > z->stream_end) { z->eof = 1; return 0; }
 memcpy(data, z->stream, n);
 z->stream += n;
 return 1;
}

static void skip(vorb *z, int n)
{
 z->stream += n;
 if (z->stream >= z->stream_end) z->eof = 1;
 return;
}

static int set_file_offset(stb_vorbis *f, unsigned int loc)
{
 f->eof = 0;
 if (f->stream_start + loc >= f->stream_end || f->stream_start + loc < f->stream_start) {
 f->stream = f->stream_end;
 f->eof = 1;
 return 0;
 } else {
 f->stream = f->stream_start + loc;
 return 1;
 }
}


static uint8_t ogg_page_header[4] = { 0x4f, 0x67, 0x67, 0x53 };

static int capture_pattern(vorb *f)
{
 if (0x4f != get8(f)) return FALSE;
 if (0x67 != get8(f)) return FALSE;
 if (0x67 != get8(f)) return FALSE;
 if (0x53 != get8(f)) return FALSE;
 return TRUE;
}

#define PAGEFLAG_continued_packet 1
#define PAGEFLAG_first_page 2
#define PAGEFLAG_last_page 4

static int start_page_no_capturepattern(vorb *f)
{
 uint32_t loc0,loc1,n;
 /* stream structure version */
 if (0 != get8(f)) return error(f, VORBIS_invalid_stream_structure_version);
 /* header flag */
 f->page_flag = get8(f);
 /* absolute granule position */
 loc0 = get32(f);
 loc1 = get32(f);
 /* @TODO: validate loc0,loc1 as valid positions?
 * stream serial number -- vorbis doesn't interleave, so discard */
 get32(f);
 /*if (f->serial != get32(f)) return error(f, VORBIS_incorrect_stream_serial_number);
 * page sequence number */
 n = get32(f);
 f->last_page = n;
 /* CRC32 */
 get32(f);
 /* page_segments */
 f->segment_count = get8(f);
 if (!getn(f, f->segments, f->segment_count))
 return error(f, VORBIS_unexpected_eof);
 /* assume we _don't_ know any the sample position of any segments */
 f->end_seg_with_known_loc = -2;
 if (loc0 != ~0U || loc1 != ~0U) {
 int i;
 /* determine which packet is the last one that will complete */
 for (i=f->segment_count-1; i >= 0; --i)
 if (f->segments[i] < 255)
 break;
 /* 'i' is now the index of the _last_ segment of a packet that ends */
 if (i >= 0) {
 f->end_seg_with_known_loc = i;
 f->known_loc_for_packet = loc0;
 }
 }
 if (f->first_decode) {
 int i,len;
 ProbedPage p;
 len = 0;
 for (i=0; i < f->segment_count; ++i)
 len += f->segments[i];
 len += 27 + f->segment_count;
 p.page_start = f->first_audio_page_offset;
 p.page_end = p.page_start + len;
 p.after_previous_page_start = p.page_start;
 p.first_decoded_sample = 0;
 p.last_decoded_sample = loc0;
 f->p_first = p;
 }
 f->next_seg = 0;
 return TRUE;
}

static int start_page(vorb *f)
{
 if (!capture_pattern(f)) return error(f, VORBIS_missing_capture_pattern);
 return start_page_no_capturepattern(f);
}

static int start_packet(vorb *f)
{
 while (f->next_seg == -1) {
 if (!start_page(f)) return FALSE;
 if (f->page_flag & PAGEFLAG_continued_packet)
 return error(f, VORBIS_continued_packet_flag_invalid);
 }
 f->last_seg = FALSE;
 f->valid_bits = 0;
 f->packet_bytes = 0;
 f->bytes_in_seg = 0;
 /* f->next_seg is now valid */
 return TRUE;
}

static int maybe_start_packet(vorb *f)
{
 if (f->next_seg == -1) {
 int x = get8(f);
 if (f->eof) return FALSE; /* EOF at page boundary is not an error! */
 if (0x4f != x ) return error(f, VORBIS_missing_capture_pattern);
 if (0x67 != get8(f)) return error(f, VORBIS_missing_capture_pattern);
 if (0x67 != get8(f)) return error(f, VORBIS_missing_capture_pattern);
 if (0x53 != get8(f)) return error(f, VORBIS_missing_capture_pattern);
 if (!start_page_no_capturepattern(f)) return FALSE;
 if (f->page_flag & PAGEFLAG_continued_packet) {
 /* set up enough state that we can read this packet if we want,
 * e.g. during recovery */
 f->last_seg = FALSE;
 f->bytes_in_seg = 0;
 return error(f, VORBIS_continued_packet_flag_invalid);
 }
 }
 return start_packet(f);
}

static int next_segment(vorb *f)
{
 int len;
 if (f->last_seg) return 0;
 if (f->next_seg == -1) {
 f->last_seg_which = f->segment_count-1; /* in case start_page fails */
 if (!start_page(f)) { f->last_seg = 1; return 0; }
 if (!(f->page_flag & PAGEFLAG_continued_packet)) return error(f, VORBIS_continued_packet_flag_invalid);
 }
 len = f->segments[f->next_seg++];
 if (len < 255) {
 f->last_seg = TRUE;
 f->last_seg_which = f->next_seg-1;
 }
 if (f->next_seg >= f->segment_count)
 f->next_seg = -1;
 assert(f->bytes_in_seg == 0);
 f->bytes_in_seg = len;
 return len;
}

#define EOP (-1)
#define INVALID_BITS (-1)

static int get8_packet_raw(vorb *f)
{
 if (!f->bytes_in_seg) { /* CLANG! */
 if (f->last_seg) return EOP;
 else if (!next_segment(f)) return EOP;
 }
 assert(f->bytes_in_seg > 0);
 --f->bytes_in_seg;
 ++f->packet_bytes;
 return get8(f);
}

static int get8_packet(vorb *f)
{
 int x = get8_packet_raw(f);
 f->valid_bits = 0;
 return x;
}

static void flush_packet(vorb *f)
{
 while (get8_packet_raw(f) != EOP);
}

/* @OPTIMIZE: this is the secondary bit decoder, so it's probably not as important
 * as the huffman decoder? */
static uint32_t get_bits(vorb *f, int n)
{
 uint32_t z;

 if (f->valid_bits < 0) return 0;
 if (f->valid_bits < n) {
 if (n > 24) {
 /* the accumulator technique below would not work correctly in this case */
 z = get_bits(f, 24);
 z += get_bits(f, n-24) << 24;
 return z;
 }
 if (f->valid_bits == 0) f->acc = 0;
 while (f->valid_bits < n) {
 int z = get8_packet_raw(f);
 if (z == EOP) {
 f->valid_bits = INVALID_BITS;
 return 0;
 }
 f->acc += z << f->valid_bits;
 f->valid_bits += 8;
 }
 }
 if (f->valid_bits < 0) return 0;
 z = f->acc & ((1 << n)-1);
 f->acc >>= n;
 f->valid_bits -= n;
 return z;
}

/* @OPTIMIZE: primary accumulator for huffman
 * expand the buffer to as many bits as possible without reading off end of packet
 * it might be nice to allow f->valid_bits and f->acc to be stored in registers,
 * e.g. cache them locally and decode locally */
static INLINE void prep_huffman(vorb *f)
{
 if (f->valid_bits <= 24) {
 if (f->valid_bits == 0) f->acc = 0;
 do {
 int z;
 if (f->last_seg && !f->bytes_in_seg) return;
 z = get8_packet_raw(f);
 if (z == EOP) return;
 f->acc += z << f->valid_bits;
 f->valid_bits += 8;
 } while (f->valid_bits <= 24);
 }
}

enum
{
 VORBIS_packet_id = 1,
 VORBIS_packet_comment = 3,
 VORBIS_packet_setup = 5
};

static int codebook_decode_scalar_raw(vorb *f, Codebook *c)
{
 int i;
 prep_huffman(f);

 assert(c->sorted_codewords || c->codewords);
 /* cases to use binary search: sorted_codewords && !c->codewords
 * sorted_codewords && c->entries > 8 */
 if (c->entries > 8 ? c->sorted_codewords!=NULL : !c->codewords) {
 /* binary search */
 uint32_t code = bit_reverse(f->acc);
 int x=0, n=c->sorted_entries, len;

 while (n > 1) {
 /* invariant: sc[x] <= code < sc[x+n] */
 int m = x + (n >> 1);
 if (c->sorted_codewords[m] <= code) {
 x = m;
 n -= (n>>1);
 } else {
 n >>= 1;
 }
 }
 /* x is now the sorted index */
 if (!c->sparse) x = c->sorted_values[x];
 /* x is now sorted index if sparse, or symbol otherwise */
 len = c->codeword_lengths[x];
 if (f->valid_bits >= len) {
 f->acc >>= len;
 f->valid_bits -= len;
 return x;
 }

 f->valid_bits = 0;
 return -1;
 }

 /* if small, linear search */
 assert(!c->sparse);
 for (i=0; i < c->entries; ++i) {
 if (c->codeword_lengths[i] == NO_CODE) continue;
 if (c->codewords[i] == (f->acc & ((1 << c->codeword_lengths[i])-1))) {
 if (f->valid_bits >= c->codeword_lengths[i]) {
 f->acc >>= c->codeword_lengths[i];
 f->valid_bits -= c->codeword_lengths[i];
 return i;
 }
 f->valid_bits = 0;
 return -1;
 }
 }

 error(f, VORBIS_invalid_stream);
 f->valid_bits = 0;
 return -1;
}


static int codebook_decode_scalar(vorb *f, Codebook *c)
{
 int i;
 if (f->valid_bits < STB_VORBIS_FAST_HUFFMAN_LENGTH)
 prep_huffman(f);
 /* fast huffman table lookup */
 i = f->acc & FAST_HUFFMAN_TABLE_MASK;
 i = c->fast_huffman[i];
 if (i >= 0) {
 f->acc >>= c->codeword_lengths[i];
 f->valid_bits -= c->codeword_lengths[i];
 if (f->valid_bits < 0) { f->valid_bits = 0; return -1; }
 return i;
 }
 return codebook_decode_scalar_raw(f,c);
}

#define DECODE_RAW(var,f,c) var = codebook_decode_scalar(f,c);

#define DECODE(var,f,c) \
 DECODE_RAW(var,f,c) \
 if (c->sparse) var = c->sorted_values[var];

#define DECODE_VQ(var,f,c) DECODE_RAW(var,f,c)

/* CODEBOOK_ELEMENT_FAST is an optimization for the CODEBOOK_FLOATS case
 * where we avoid one addition */
#ifndef STB_VORBIS_CODEBOOK_FLOATS
 #define CODEBOOK_ELEMENT(c,off) (c->multiplicands[off] * c->delta_value + c->minimum_value)
 #define CODEBOOK_ELEMENT_FAST(c,off) (c->multiplicands[off] * c->delta_value)
 #define CODEBOOK_ELEMENT_BASE(c) (c->minimum_value)
#else
 #define CODEBOOK_ELEMENT(c,off) (c->multiplicands[off])
 #define CODEBOOK_ELEMENT_FAST(c,off) (c->multiplicands[off])
 #define CODEBOOK_ELEMENT_BASE(c) (0)
#endif

static int codebook_decode_start(vorb *f, Codebook *c)
{
 int z = -1;

 /* type 0 is only legal in a scalar context */
 if (c->lookup_type == 0)
 error(f, VORBIS_invalid_stream);
 else {
 DECODE_VQ(z,f,c);
 if (c->sparse) assert(z < c->sorted_entries);
 if (z < 0) { /* check for EOP */
 if (!f->bytes_in_seg)
 if (f->last_seg)
 return z;
 error(f, VORBIS_invalid_stream);
 }
 }
 return z;
}

static int codebook_decode(vorb *f, Codebook *c, float *output, int len)
{
 int i,z = codebook_decode_start(f,c);
 if (z < 0) return FALSE;
 if (len > c->dimensions) len = c->dimensions;

 z *= c->dimensions;
 if (c->sequence_p) {
 float last = CODEBOOK_ELEMENT_BASE(c);
 for (i=0; i < len; ++i) {
 float val = CODEBOOK_ELEMENT_FAST(c,z+i) + last;
 output[i] += val;
 last = val + c->minimum_value;
 }
 } else {
 float last = CODEBOOK_ELEMENT_BASE(c);
 for (i=0; i < len; ++i) {
 output[i] += CODEBOOK_ELEMENT_FAST(c,z+i) + last;
 }
 }

 return TRUE;
}

static int codebook_decode_step(vorb *f, Codebook *c, float *output, int len, int step)
{
 int i,z = codebook_decode_start(f,c);
 float last = CODEBOOK_ELEMENT_BASE(c);
 if (z < 0) return FALSE;
 if (len > c->dimensions) len = c->dimensions;

 z *= c->dimensions;
 for (i=0; i < len; ++i) {
 float val = CODEBOOK_ELEMENT_FAST(c,z+i) + last;
 output[i*step] += val;
 if (c->sequence_p) last = val;
 }

 return TRUE;
}

static int codebook_decode_deinterleave_repeat(vorb *f, Codebook *c, float **outputs, int ch, int *c_inter_p, int *p_inter_p, int len, int total_decode)
{
 int c_inter = *c_inter_p;
 int p_inter = *p_inter_p;
 int i,z, effective = c->dimensions;

 /* type 0 is only legal in a scalar context */
 if (c->lookup_type == 0) return error(f, VORBIS_invalid_stream);

 while (total_decode > 0) {
 float last = CODEBOOK_ELEMENT_BASE(c);
 DECODE_VQ(z,f,c);
 assert(!c->sparse || z < c->sorted_entries);
 if (z < 0) {
 if (!f->bytes_in_seg)
 if (f->last_seg) return FALSE;
 return error(f, VORBIS_invalid_stream);
 }

 /* if this will take us off the end of the buffers, stop short!
 * we check by computing the length of the virtual interleaved
 * buffer (len*ch), our current offset within it (p_inter*ch)+(c_inter),
 * and the length we'll be using (effective) */
 if (c_inter + p_inter*ch + effective > len * ch) {
 effective = len*ch - (p_inter*ch - c_inter);
 }

 z *= c->dimensions;
 if (c->sequence_p) {
 for (i=0; i < effective; ++i) {
 float val = CODEBOOK_ELEMENT_FAST(c,z+i) + last;
 if (outputs[c_inter])
 outputs[c_inter][p_inter] += val;
 if (++c_inter == ch) { c_inter = 0; ++p_inter; }
 last = val;
 }
 } else {
 for (i=0; i < effective; ++i) {
 float val = CODEBOOK_ELEMENT_FAST(c,z+i) + last;
 if (outputs[c_inter])
 outputs[c_inter][p_inter] += val;
 if (++c_inter == ch) { c_inter = 0; ++p_inter; }
 }
 }

 total_decode -= effective;
 }
 *c_inter_p = c_inter;
 *p_inter_p = p_inter;
 return TRUE;
}

static int codebook_decode_deinterleave_repeat_2(vorb *f, Codebook *c, float **outputs, int *c_inter_p, int *p_inter_p, int len, int total_decode)
{
 int c_inter = *c_inter_p;
 int p_inter = *p_inter_p;
 int i,z, effective = c->dimensions;

 /* type 0 is only legal in a scalar context */
 if (c->lookup_type == 0) return error(f, VORBIS_invalid_stream);

 while (total_decode > 0) {
 float last = CODEBOOK_ELEMENT_BASE(c);
 DECODE_VQ(z,f,c);

 if (z < 0) {
 if (!f->bytes_in_seg)
 if (f->last_seg) return FALSE;
 return error(f, VORBIS_invalid_stream);
 }

 /* if this will take us off the end of the buffers, stop short!
 * we check by computing the length of the virtual interleaved
 * buffer (len*ch), our current offset within it (p_inter*ch)+(c_inter),
 * and the length we'll be using (effective)
 */
 if (c_inter + p_inter*2 + effective > len * 2) {
 effective = len*2 - (p_inter*2 - c_inter);
 }

 {
 z *= c->dimensions;
 if (c->sequence_p) {
 /* haven't optimized this case because I don't have any examples */
 for (i=0; i < effective; ++i) {
 float val = CODEBOOK_ELEMENT_FAST(c,z+i) + last;
 if (outputs[c_inter])
 outputs[c_inter][p_inter] += val;
 if (++c_inter == 2) { c_inter = 0; ++p_inter; }
 last = val;
 }
 } else {
 i=0;
 if (c_inter == 1) {
 float val = CODEBOOK_ELEMENT_FAST(c,z+i) + last;
 if (outputs[c_inter])
 outputs[c_inter][p_inter] += val;
 c_inter = 0; ++p_inter;
 ++i;
 }
 {
 float *z0 = outputs[0];
 float *z1 = outputs[1];
 for (; i+1 < effective;) {
 float v0 = CODEBOOK_ELEMENT_FAST(c,z+i) + last;
 float v1 = CODEBOOK_ELEMENT_FAST(c,z+i+1) + last;
 if (z0)
 z0[p_inter] += v0;
 if (z1)
 z1[p_inter] += v1;
 ++p_inter;
 i += 2;
 }
 }
 if (i < effective) {
 float val = CODEBOOK_ELEMENT_FAST(c,z+i) + last;
 if (outputs[c_inter])
 outputs[c_inter][p_inter] += val;
 if (++c_inter == 2) { c_inter = 0; ++p_inter; }
 }
 }
 }

 total_decode -= effective;
 }
 *c_inter_p = c_inter;
 *p_inter_p = p_inter;
 return TRUE;
}

static int predict_point(int x, int x0, int x1, int y0, int y1)
{
 int dy = y1 - y0;
 int adx = x1 - x0;
 /* @OPTIMIZE: force int division to round in the right direction... is this necessary on x86? */
 int err = abs(dy) * (x - x0);
 int off = err / adx;
 return dy < 0 ? y0 - off : y0 + off;
}

/* the following table is block-copied from the specification */
static float inverse_db_table[256] =
{
 1.0649863e-07f, 1.1341951e-07f, 1.2079015e-07f, 1.2863978e-07f,
 1.3699951e-07f, 1.4590251e-07f, 1.5538408e-07f, 1.6548181e-07f,
 1.7623575e-07f, 1.8768855e-07f, 1.9988561e-07f, 2.1287530e-07f,
 2.2670913e-07f, 2.4144197e-07f, 2.5713223e-07f, 2.7384213e-07f,
 2.9163793e-07f, 3.1059021e-07f, 3.3077411e-07f, 3.5226968e-07f,
 3.7516214e-07f, 3.9954229e-07f, 4.2550680e-07f, 4.5315863e-07f,
 4.8260743e-07f, 5.1396998e-07f, 5.4737065e-07f, 5.8294187e-07f,
 6.2082472e-07f, 6.6116941e-07f, 7.0413592e-07f, 7.4989464e-07f,
 7.9862701e-07f, 8.5052630e-07f, 9.0579828e-07f, 9.6466216e-07f,
 1.0273513e-06f, 1.0941144e-06f, 1.1652161e-06f, 1.2409384e-06f,
 1.3215816e-06f, 1.4074654e-06f, 1.4989305e-06f, 1.5963394e-06f,
 1.7000785e-06f, 1.8105592e-06f, 1.9282195e-06f, 2.0535261e-06f,
 2.1869758e-06f, 2.3290978e-06f, 2.4804557e-06f, 2.6416497e-06f,
 2.8133190e-06f, 2.9961443e-06f, 3.1908506e-06f, 3.3982101e-06f,
 3.6190449e-06f, 3.8542308e-06f, 4.1047004e-06f, 4.3714470e-06f,
 4.6555282e-06f, 4.9580707e-06f, 5.2802740e-06f, 5.6234160e-06f,
 5.9888572e-06f, 6.3780469e-06f, 6.7925283e-06f, 7.2339451e-06f,
 7.7040476e-06f, 8.2047000e-06f, 8.7378876e-06f, 9.3057248e-06f,
 9.9104632e-06f, 1.0554501e-05f, 1.1240392e-05f, 1.1970856e-05f,
 1.2748789e-05f, 1.3577278e-05f, 1.4459606e-05f, 1.5399272e-05f,
 1.6400004e-05f, 1.7465768e-05f, 1.8600792e-05f, 1.9809576e-05f,
 2.1096914e-05f, 2.2467911e-05f, 2.3928002e-05f, 2.5482978e-05f,
 2.7139006e-05f, 2.8902651e-05f, 3.0780908e-05f, 3.2781225e-05f,
 3.4911534e-05f, 3.7180282e-05f, 3.9596466e-05f, 4.2169667e-05f,
 4.4910090e-05f, 4.7828601e-05f, 5.0936773e-05f, 5.4246931e-05f,
 5.7772202e-05f, 6.1526565e-05f, 6.5524908e-05f, 6.9783085e-05f,
 7.4317983e-05f, 7.9147585e-05f, 8.4291040e-05f, 8.9768747e-05f,
 9.5602426e-05f, 0.00010181521f, 0.00010843174f, 0.00011547824f,
 0.00012298267f, 0.00013097477f, 0.00013948625f, 0.00014855085f,
 0.00015820453f, 0.00016848555f, 0.00017943469f, 0.00019109536f,
 0.00020351382f, 0.00021673929f, 0.00023082423f, 0.00024582449f,
 0.00026179955f, 0.00027881276f, 0.00029693158f, 0.00031622787f,
 0.00033677814f, 0.00035866388f, 0.00038197188f, 0.00040679456f,
 0.00043323036f, 0.00046138411f, 0.00049136745f, 0.00052329927f,
 0.00055730621f, 0.00059352311f, 0.00063209358f, 0.00067317058f,
 0.00071691700f, 0.00076350630f, 0.00081312324f, 0.00086596457f,
 0.00092223983f, 0.00098217216f, 0.0010459992f, 0.0011139742f,
 0.0011863665f, 0.0012634633f, 0.0013455702f, 0.0014330129f,
 0.0015261382f, 0.0016253153f, 0.0017309374f, 0.0018434235f,
 0.0019632195f, 0.0020908006f, 0.0022266726f, 0.0023713743f,
 0.0025254795f, 0.0026895994f, 0.0028643847f, 0.0030505286f,
 0.0032487691f, 0.0034598925f, 0.0036847358f, 0.0039241906f,
 0.0041792066f, 0.0044507950f, 0.0047400328f, 0.0050480668f,
 0.0053761186f, 0.0057254891f, 0.0060975636f, 0.0064938176f,
 0.0069158225f, 0.0073652516f, 0.0078438871f, 0.0083536271f,
 0.0088964928f, 0.009474637f, 0.010090352f, 0.010746080f,
 0.011444421f, 0.012188144f, 0.012980198f, 0.013823725f,
 0.014722068f, 0.015678791f, 0.016697687f, 0.017782797f,
 0.018938423f, 0.020169149f, 0.021479854f, 0.022875735f,
 0.024362330f, 0.025945531f, 0.027631618f, 0.029427276f,
 0.031339626f, 0.033376252f, 0.035545228f, 0.037855157f,
 0.040315199f, 0.042935108f, 0.045725273f, 0.048696758f,
 0.051861348f, 0.055231591f, 0.058820850f, 0.062643361f,
 0.066714279f, 0.071049749f, 0.075666962f, 0.080584227f,
 0.085821044f, 0.091398179f, 0.097337747f, 0.10366330f,
 0.11039993f, 0.11757434f, 0.12521498f, 0.13335215f,
 0.14201813f, 0.15124727f, 0.16107617f, 0.17154380f,
 0.18269168f, 0.19456402f, 0.20720788f, 0.22067342f,
 0.23501402f, 0.25028656f, 0.26655159f, 0.28387361f,
 0.30232132f, 0.32196786f, 0.34289114f, 0.36517414f,
 0.38890521f, 0.41417847f, 0.44109412f, 0.46975890f,
 0.50028648f, 0.53279791f, 0.56742212f, 0.60429640f,
 0.64356699f, 0.68538959f, 0.72993007f, 0.77736504f,
 0.82788260f, 0.88168307f, 0.9389798f, 1.0f
};


/* @OPTIMIZE: if you want to replace this bresenham line-drawing routine,
 * note that you must produce bit-identical output to decode correctly;
 * this specific sequence of operations is specified in the spec (it's
 * drawing integer-quantized frequency-space lines that the encoder
 * expects to be exactly the same)
 * ... also, isn't the whole point of Bresenham's algorithm to NOT
 * have to divide in the setup? sigh.
 */
#define LINE_OP(a,b) a *= b

static INLINE void draw_line(float *output, int x0, int y0, int x1, int y1, int n)
{
 int dy = y1 - y0;
 int adx = x1 - x0;
 int ady = abs(dy);
 int x=x0,y=y0;
 int err = 0;
 int sy;
 int base = dy / adx;

 if (dy < 0)
 sy = base - 1;
 else
 sy = base+1;

 ady -= abs(base) * adx;
 if (x1 > n) x1 = n;
 LINE_OP(output[x], inverse_db_table[y]);
 for (++x; x < x1; ++x) {
 err += ady;
 if (err >= adx) {
 err -= adx;
 y += sy;
 } else
 y += base;
 LINE_OP(output[x], inverse_db_table[y]);
 }
}

static int residue_decode(vorb *f, Codebook *book, float *target, int offset, int n, int rtype)
{
 int k;
 if (rtype == 0) {
 int step = n / book->dimensions;
 for (k=0; k < step; ++k)
 if (!codebook_decode_step(f, book, target+offset+k, n-offset-k, step))
 return FALSE;
 } else {
 for (k=0; k < n; ) {
 if (!codebook_decode(f, book, target+offset, n-k))
 return FALSE;
 k += book->dimensions;
 offset += book->dimensions;
 }
 }
 return TRUE;
}

static void decode_residue(vorb *f, float *residue_buffers[], int ch, int n, int rn, uint8_t *do_not_decode)
{
 int i,j,pass;
 Residue *r = f->residue_config + rn;
 int rtype = f->residue_types[rn];
 int c = r->classbook;
 int classwords = f->codebooks[c].dimensions;
 int n_read = r->end - r->begin;
 int part_read = n_read / r->part_size;
 int temp_alloc_point = temp_alloc_save(f);
 uint8_t ***part_classdata = (uint8_t ***) temp_block_array(f,f->channels, part_read * sizeof(**part_classdata));

 for (i=0; i < ch; ++i)
 if (!do_not_decode[i])
 memset(residue_buffers[i], 0, sizeof(float) * n);

 if (rtype == 2 && ch != 1) {
 for (j=0; j < ch; ++j)
 if (!do_not_decode[j])
 break;
 if (j == ch)
 goto done;

 for (pass=0; pass < 8; ++pass) {
 int pcount = 0, class_set = 0;
 if (ch == 2) {
 while (pcount < part_read) {
 int z = r->begin + pcount*r->part_size;
 int c_inter = (z & 1), p_inter = z>>1;
 if (pass == 0) {
 Codebook *c = f->codebooks+r->classbook;
 int q;
 DECODE(q,f,c);
 if (q == EOP) goto done;
 part_classdata[0][class_set] = r->classdata[q];
 }
 for (i=0; i < classwords && pcount < part_read; ++i, ++pcount) {
 int z = r->begin + pcount*r->part_size;
 int c = part_classdata[0][class_set][i];
 int b = r->residue_books[c][pass];
 if (b >= 0) {
 Codebook *book = f->codebooks + b;
 /* saves 1% */
 if (!codebook_decode_deinterleave_repeat_2(f, book, residue_buffers, &c_inter, &p_inter, n, r->part_size))
 goto done;
 } else {
 z += r->part_size;
 c_inter = z & 1;
 p_inter = z >> 1;
 }
 }
 ++class_set;
 }
 } else if (ch == 1) {
 while (pcount < part_read) {
 int z = r->begin + pcount*r->part_size;
 int c_inter = 0, p_inter = z;
 if (pass == 0) {
 Codebook *c = f->codebooks+r->classbook;
 int q;
 DECODE(q,f,c);
 if (q == EOP) goto done;
 part_classdata[0][class_set] = r->classdata[q];
 }
 for (i=0; i < classwords && pcount < part_read; ++i, ++pcount) {
 int z = r->begin + pcount*r->part_size;
 int c = part_classdata[0][class_set][i];
 int b = r->residue_books[c][pass];
 if (b >= 0) {
 Codebook *book = f->codebooks + b;
 if (!codebook_decode_deinterleave_repeat(f, book, residue_buffers, ch, &c_inter, &p_inter, n, r->part_size))
 goto done;
 } else {
 z += r->part_size;
 c_inter = 0;
 p_inter = z;
 }
 }
 ++class_set;
 }
 } else {
 while (pcount < part_read) {
 int z = r->begin + pcount*r->part_size;
 int c_inter = z % ch, p_inter = z/ch;
 if (pass == 0) {
 Codebook *c = f->codebooks+r->classbook;
 int q;
 DECODE(q,f,c);
 if (q == EOP) goto done;
 part_classdata[0][class_set] = r->classdata[q];
 }
 for (i=0; i < classwords && pcount < part_read; ++i, ++pcount) {
 int z = r->begin + pcount*r->part_size;
 int c = part_classdata[0][class_set][i];
 int b = r->residue_books[c][pass];
 if (b >= 0) {
 Codebook *book = f->codebooks + b;
 if (!codebook_decode_deinterleave_repeat(f, book, residue_buffers, ch, &c_inter, &p_inter, n, r->part_size))
 goto done;
 } else {
 z += r->part_size;
 c_inter = z % ch;
 p_inter = z / ch;
 }
 }
 ++class_set;
 }
 }
 }
 goto done;
 }

 for (pass=0; pass < 8; ++pass) {
 int pcount = 0, class_set=0;
 while (pcount < part_read) {
 if (pass == 0) {
 for (j=0; j < ch; ++j) {
 if (!do_not_decode[j]) {
 Codebook *c = f->codebooks+r->classbook;
 int temp;
 DECODE(temp,f,c);
 if (temp == EOP) goto done;
 part_classdata[j][class_set] = r->classdata[temp];
 }
 }
 }
 for (i=0; i < classwords && pcount < part_read; ++i, ++pcount) {
 for (j=0; j < ch; ++j) {
 if (!do_not_decode[j]) {
 int c = part_classdata[j][class_set][i];
 int b = r->residue_books[c][pass];
 if (b >= 0) {
 float *target = residue_buffers[j];
 int offset = r->begin + pcount * r->part_size;
 int n = r->part_size;
 Codebook *book = f->codebooks + b;
 if (!residue_decode(f, book, target, offset, n, rtype))
 goto done;
 }
 }
 }
 }
 ++class_set;
 }
 }
 done:
 temp_alloc_restore(f,temp_alloc_point);
}


#ifndef LIBVORBIS_MDCT
#define LIBVORBIS_MDCT 0
#endif

#if LIBVORBIS_MDCT
/* directly call the vorbis MDCT using an interface documented
 * by Jeff Roberts... useful for performance comparison */
typedef struct
{
 int n;
 int log2n;

 float *trig;
 int *bitrev;

 float scale;
} mdct_lookup;

extern void mdct_init(mdct_lookup *lookup, int n);
extern void mdct_clear(mdct_lookup *l);
extern void mdct_backward(mdct_lookup *init, float *in, float *out);

mdct_lookup M1,M2;

void inverse_mdct(float *buffer, int n, vorb *f, int blocktype)
{
 mdct_lookup *M;
 if (M1.n == n) M = &M1;
 else if (M2.n == n) M = &M2;
 else if (M1.n == 0) { mdct_init(&M1, n); M = &M1; }
 else {
 if (M2.n) __asm int 3;
 mdct_init(&M2, n);
 M = &M2;
 }

 mdct_backward(M, buffer, buffer);
}
#endif


/* the following were split out into separate functions while optimizing;
 * they could be pushed back up but eh. __forceinline showed no change;
 * they're probably already being inlined. */
static void imdct_step3_iter0_loop(int n, float *e, int i_off, int k_off, float *A)
{
 float *ee0 = e + i_off;
 float *ee2 = ee0 + k_off;
 int i;

 assert((n & 3) == 0);
 for (i=(n>>2); i > 0; --i) {
 float k00_20, k01_21;
 k00_20 = ee0[ 0] - ee2[ 0];
 k01_21 = ee0[-1] - ee2[-1];
 ee0[ 0] += ee2[ 0];/*ee0[ 0] = ee0[ 0] + ee2[ 0]; */
 ee0[-1] += ee2[-1];/*ee0[-1] = ee0[-1] + ee2[-1]; */
 ee2[ 0] = k00_20 * A[0] - k01_21 * A[1];
 ee2[-1] = k01_21 * A[0] + k00_20 * A[1];
 A += 8;

 k00_20 = ee0[-2] - ee2[-2];
 k01_21 = ee0[-3] - ee2[-3];
 ee0[-2] += ee2[-2];/*ee0[-2] = ee0[-2] + ee2[-2]; */
 ee0[-3] += ee2[-3];/*ee0[-3] = ee0[-3] + ee2[-3]; */
 ee2[-2] = k00_20 * A[0] - k01_21 * A[1];
 ee2[-3] = k01_21 * A[0] + k00_20 * A[1];
 A += 8;

 k00_20 = ee0[-4] - ee2[-4];
 k01_21 = ee0[-5] - ee2[-5];
 ee0[-4] += ee2[-4];/*ee0[-4] = ee0[-4] + ee2[-4]; */
 ee0[-5] += ee2[-5];/*ee0[-5] = ee0[-5] + ee2[-5]; */
 ee2[-4] = k00_20 * A[0] - k01_21 * A[1];
 ee2[-5] = k01_21 * A[0] + k00_20 * A[1];
 A += 8;

 k00_20 = ee0[-6] - ee2[-6];
 k01_21 = ee0[-7] - ee2[-7];
 ee0[-6] += ee2[-6];/*ee0[-6] = ee0[-6] + ee2[-6]; */
 ee0[-7] += ee2[-7];/*ee0[-7] = ee0[-7] + ee2[-7]; */
 ee2[-6] = k00_20 * A[0] - k01_21 * A[1];
 ee2[-7] = k01_21 * A[0] + k00_20 * A[1];
 A += 8;
 ee0 -= 8;
 ee2 -= 8;
 }
}

static void imdct_step3_inner_r_loop(int lim, float *e, int d0, int k_off, float *A, int k1)
{
 int i;
 float k00_20, k01_21;

 float *e0 = e + d0;
 float *e2 = e0 + k_off;

 for (i=lim >> 2; i > 0; --i) {
 k00_20 = e0[-0] - e2[-0];
 k01_21 = e0[-1] - e2[-1];
 e0[-0] += e2[-0];/*e0[-0] = e0[-0] + e2[-0]; */
 e0[-1] += e2[-1];/*e0[-1] = e0[-1] + e2[-1]; */
 e2[-0] = (k00_20)*A[0] - (k01_21) * A[1];
 e2[-1] = (k01_21)*A[0] + (k00_20) * A[1];

 A += k1;

 k00_20 = e0[-2] - e2[-2];
 k01_21 = e0[-3] - e2[-3];
 e0[-2] += e2[-2];/*e0[-2] = e0[-2] + e2[-2]; */
 e0[-3] += e2[-3];/*e0[-3] = e0[-3] + e2[-3]; */
 e2[-2] = (k00_20)*A[0] - (k01_21) * A[1];
 e2[-3] = (k01_21)*A[0] + (k00_20) * A[1];

 A += k1;

 k00_20 = e0[-4] - e2[-4];
 k01_21 = e0[-5] - e2[-5];
 e0[-4] += e2[-4];/*e0[-4] = e0[-4] + e2[-4]; */
 e0[-5] += e2[-5];/*e0[-5] = e0[-5] + e2[-5]; */
 e2[-4] = (k00_20)*A[0] - (k01_21) * A[1];
 e2[-5] = (k01_21)*A[0] + (k00_20) * A[1];

 A += k1;

 k00_20 = e0[-6] - e2[-6];
 k01_21 = e0[-7] - e2[-7];
 e0[-6] += e2[-6];/*e0[-6] = e0[-6] + e2[-6]; */
 e0[-7] += e2[-7];/*e0[-7] = e0[-7] + e2[-7]; */
 e2[-6] = (k00_20)*A[0] - (k01_21) * A[1];
 e2[-7] = (k01_21)*A[0] + (k00_20) * A[1];

 e0 -= 8;
 e2 -= 8;

 A += k1;
 }
}

static void imdct_step3_inner_s_loop(int n, float *e, int i_off, int k_off, float *A, int a_off, int k0)
{
 int i;
 float A0 = A[0];
 float A1 = A[0+1];
 float A2 = A[0+a_off];
 float A3 = A[0+a_off+1];
 float A4 = A[0+a_off*2+0];
 float A5 = A[0+a_off*2+1];
 float A6 = A[0+a_off*3+0];
 float A7 = A[0+a_off*3+1];

 float k00,k11;

 float *ee0 = e +i_off;
 float *ee2 = ee0+k_off;

 for (i=n; i > 0; --i) {
 k00 = ee0[ 0] - ee2[ 0];
 k11 = ee0[-1] - ee2[-1];
 ee0[ 0] = ee0[ 0] + ee2[ 0];
 ee0[-1] = ee0[-1] + ee2[-1];
 ee2[ 0] = (k00) * A0 - (k11) * A1;
 ee2[-1] = (k11) * A0 + (k00) * A1;

 k00 = ee0[-2] - ee2[-2];
 k11 = ee0[-3] - ee2[-3];
 ee0[-2] = ee0[-2] + ee2[-2];
 ee0[-3] = ee0[-3] + ee2[-3];
 ee2[-2] = (k00) * A2 - (k11) * A3;
 ee2[-3] = (k11) * A2 + (k00) * A3;

 k00 = ee0[-4] - ee2[-4];
 k11 = ee0[-5] - ee2[-5];
 ee0[-4] = ee0[-4] + ee2[-4];
 ee0[-5] = ee0[-5] + ee2[-5];
 ee2[-4] = (k00) * A4 - (k11) * A5;
 ee2[-5] = (k11) * A4 + (k00) * A5;

 k00 = ee0[-6] - ee2[-6];
 k11 = ee0[-7] - ee2[-7];
 ee0[-6] = ee0[-6] + ee2[-6];
 ee0[-7] = ee0[-7] + ee2[-7];
 ee2[-6] = (k00) * A6 - (k11) * A7;
 ee2[-7] = (k11) * A6 + (k00) * A7;

 ee0 -= k0;
 ee2 -= k0;
 }
}

static INLINE void iter_54(float *z)
{
 float k00,k11,k22,k33;
 float y0,y1,y2,y3;

 k00 = z[ 0] - z[-4];
 y0 = z[ 0] + z[-4];
 y2 = z[-2] + z[-6];
 k22 = z[-2] - z[-6];

 z[-0] = y0 + y2; /* z0 + z4 + z2 + z6 */
 z[-2] = y0 - y2; /* z0 + z4 - z2 - z6 */

 /* done with y0,y2 */

 k33 = z[-3] - z[-7];

 z[-4] = k00 + k33; /* z0 - z4 + z3 - z7 */
 z[-6] = k00 - k33; /* z0 - z4 - z3 + z7 */

 /* done with k33 */

 k11 = z[-1] - z[-5];
 y1 = z[-1] + z[-5];
 y3 = z[-3] + z[-7];

 z[-1] = y1 + y3; /* z1 + z5 + z3 + z7 */
 z[-3] = y1 - y3; /* z1 + z5 - z3 - z7 */
 z[-5] = k11 - k22; /* z1 - z5 + z2 - z6 */
 z[-7] = k11 + k22; /* z1 - z5 - z2 + z6 */
}

static void imdct_step3_inner_s_loop_ld654(int n, float *e, int i_off, float *A, int base_n)
{
 int a_off = base_n >> 3;
 float A2 = A[0+a_off];
 float *z = e + i_off;
 float *base = z - 16 * n;

 while (z > base) {
 float k00,k11;

 k00 = z[-0] - z[-8];
 k11 = z[-1] - z[-9];
 z[-0] = z[-0] + z[-8];
 z[-1] = z[-1] + z[-9];
 z[-8] = k00;
 z[-9] = k11 ;

 k00 = z[ -2] - z[-10];
 k11 = z[ -3] - z[-11];
 z[ -2] = z[ -2] + z[-10];
 z[ -3] = z[ -3] + z[-11];
 z[-10] = (k00+k11) * A2;
 z[-11] = (k11-k00) * A2;

 k00 = z[-12] - z[ -4]; /* reverse to avoid a unary negation */
 k11 = z[ -5] - z[-13];
 z[ -4] = z[ -4] + z[-12];
 z[ -5] = z[ -5] + z[-13];
 z[-12] = k11;
 z[-13] = k00;

 k00 = z[-14] - z[ -6]; /* reverse to avoid a unary negation */
 k11 = z[ -7] - z[-15];
 z[ -6] = z[ -6] + z[-14];
 z[ -7] = z[ -7] + z[-15];
 z[-14] = (k00+k11) * A2;
 z[-15] = (k00-k11) * A2;

 iter_54(z);
 iter_54(z-8);
 z -= 16;
 }
}

static void inverse_mdct(float *buffer, int n, vorb *f, int blocktype)
{
 int n2 = n >> 1, n4 = n >> 2, n8 = n >> 3, l;
 int ld;
 /* @OPTIMIZE: reduce register pressure by using fewer variables? */
 int save_point = temp_alloc_save(f);
 float *buf2 = (float *) temp_alloc(f, n2 * sizeof(*buf2));
 float *u=NULL,*v=NULL;
 /* twiddle factors */
 float *A = f->A[blocktype];

 /* IMDCT algorithm from "The use of multirate filter banks for coding of high quality digital audio"
 * See notes about bugs in that paper in less-optimal implementation 'inverse_mdct_old' after this function.

 * kernel from paper


 * merged:
 * copy and reflect spectral data
 * step 0

 * note that it turns out that the items added together during
 * this step are, in fact, being added to themselves (as reflected
 * by step 0). inexplicable inefficiency! this became obvious
 * once I combined the passes.

 * so there's a missing 'times 2' here (for adding X to itself).
 * this propogates through linearly to the end, where the numbers
 * are 1/2 too small, and need to be compensated for.
 */

 {
 float *d,*e, *AA, *e_stop;
 d = &buf2[n2-2];
 AA = A;
 e = &buffer[0];
 e_stop = &buffer[n2];
 while (e != e_stop) {
 d[1] = (e[0] * AA[0] - e[2]*AA[1]);
 d[0] = (e[0] * AA[1] + e[2]*AA[0]);
 d -= 2;
 AA += 2;
 e += 4;
 }

 e = &buffer[n2-3];
 while (d >= buf2) {
 d[1] = (-e[2] * AA[0] - -e[0]*AA[1]);
 d[0] = (-e[2] * AA[1] + -e[0]*AA[0]);
 d -= 2;
 AA += 2;
 e -= 4;
 }
 }

 /* now we use symbolic names for these, so that we can
 * possibly swap their meaning as we change which operations
 * are in place */

 u = buffer;
 v = buf2;

 /* step 2 (paper output is w, now u)
 * this could be in place, but the data ends up in the wrong
 * place... _somebody_'s got to swap it, so this is nominated */
 {
 float *AA = &A[n2-8];
 float *d0,*d1, *e0, *e1;

 e0 = &v[n4];
 e1 = &v[0];

 d0 = &u[n4];
 d1 = &u[0];

 while (AA >= A) {
 float v40_20, v41_21;

 v41_21 = e0[1] - e1[1];
 v40_20 = e0[0] - e1[0];
 d0[1] = e0[1] + e1[1];
 d0[0] = e0[0] + e1[0];
 d1[1] = v41_21*AA[4] - v40_20*AA[5];
 d1[0] = v40_20*AA[4] + v41_21*AA[5];

 v41_21 = e0[3] - e1[3];
 v40_20 = e0[2] - e1[2];
 d0[3] = e0[3] + e1[3];
 d0[2] = e0[2] + e1[2];
 d1[3] = v41_21*AA[0] - v40_20*AA[1];
 d1[2] = v40_20*AA[0] + v41_21*AA[1];

 AA -= 8;

 d0 += 4;
 d1 += 4;
 e0 += 4;
 e1 += 4;
 }
 }

 /* step 3 */
 ld = ilog(n) - 1; /* ilog is off-by-one from normal definitions */

 /* optimized step 3:

 * the original step3 loop can be nested r inside s or s inside r;
 * it's written originally as s inside r, but this is dumb when r
 * iterates many times, and s few. So I have two copies of it and
 * switch between them halfway.

 * this is iteration 0 of step 3 */
 imdct_step3_iter0_loop(n >> 4, u, n2-1-n4*0, -(n >> 3), A);
 imdct_step3_iter0_loop(n >> 4, u, n2-1-n4*1, -(n >> 3), A);

 /* this is iteration 1 of step 3 */
 imdct_step3_inner_r_loop(n >> 5, u, n2-1 - n8*0, -(n >> 4), A, 16);
 imdct_step3_inner_r_loop(n >> 5, u, n2-1 - n8*1, -(n >> 4), A, 16);
 imdct_step3_inner_r_loop(n >> 5, u, n2-1 - n8*2, -(n >> 4), A, 16);
 imdct_step3_inner_r_loop(n >> 5, u, n2-1 - n8*3, -(n >> 4), A, 16);

 l=2;
 for (; l < (ld-3)>>1; ++l) {
 int k0 = n >> (l+2), k0_2 = k0>>1;
 int lim = 1 << (l+1);
 int i;
 for (i=0; i < lim; ++i)
 imdct_step3_inner_r_loop(n >> (l+4), u, n2-1 - k0*i, -k0_2, A, 1 << (l+3));
 }

 for (; l < ld-6; ++l) {
 int k0 = n >> (l+2), k1 = 1 << (l+3), k0_2 = k0>>1;
 int rlim = n >> (l+6), r;
 int lim = 1 << (l+1);
 int i_off;
 float *A0 = A;
 i_off = n2-1;
 for (r=rlim; r > 0; --r) {
 imdct_step3_inner_s_loop(lim, u, i_off, -k0_2, A0, k1, k0);
 A0 += k1*4;
 i_off -= 8;
 }
 }

 /* iterations with count:
 * ld-6,-5,-4 all interleaved together
 * the big win comes from getting rid of needless flops
 * due to the constants on pass 5 & 4 being all 1 and 0;
 * combining them to be simultaneous to improve cache made little difference
 */
 imdct_step3_inner_s_loop_ld654(n >> 5, u, n2-1, A, n);

 /* output is u

 * step 4, 5, and 6
 * cannot be in-place because of step 5 */
 {
 uint16_t *bitrev = f->bit_reverse[blocktype];
 /* weirdly, I'd have thought reading sequentially and writing
 * erratically would have been better than vice-versa, but in
 * fact that's not what my testing showed. (That is, with
 * j = bitreverse(i), do you read i and write j, or read j and write i.) */

 float *d0 = &v[n4-4];
 float *d1 = &v[n2-4];
 while (d0 >= v) {
 int k4;

 k4 = bitrev[0];
 d1[3] = u[k4+0];
 d1[2] = u[k4+1];
 d0[3] = u[k4+2];
 d0[2] = u[k4+3];

 k4 = bitrev[1];
 d1[1] = u[k4+0];
 d1[0] = u[k4+1];
 d0[1] = u[k4+2];
 d0[0] = u[k4+3];

 d0 -= 4;
 d1 -= 4;
 bitrev += 2;
 }
 }
 /* (paper output is u, now v) */


 /* data must be in buf2 */
 assert(v == buf2);

 /* step 7 (paper output is v, now v)
 * this is now in place */
 {
 float *C = f->C[blocktype];
 float *d, *e;

 d = v;
 e = v + n2 - 4;

 while (d < e) {
 float a02,a11,b0,b1,b2,b3;

 a02 = d[0] - e[2];
 a11 = d[1] + e[3];

 b0 = C[1]*a02 + C[0]*a11;
 b1 = C[1]*a11 - C[0]*a02;

 b2 = d[0] + e[ 2];
 b3 = d[1] - e[ 3];

 d[0] = b2 + b0;
 d[1] = b3 + b1;
 e[2] = b2 - b0;
 e[3] = b1 - b3;

 a02 = d[2] - e[0];
 a11 = d[3] + e[1];

 b0 = C[3]*a02 + C[2]*a11;
 b1 = C[3]*a11 - C[2]*a02;

 b2 = d[2] + e[ 0];
 b3 = d[3] - e[ 1];

 d[2] = b2 + b0;
 d[3] = b3 + b1;
 e[0] = b2 - b0;
 e[1] = b1 - b3;

 C += 4;
 d += 4;
 e -= 4;
 }
 }

 /* data must be in buf2


 * step 8+decode (paper output is X, now buffer)
 * this generates pairs of data a la 8 and pushes them directly through
 * the decode kernel (pushing rather than pulling) to avoid having
 * to make another pass later

 * this cannot POSSIBLY be in place, so we refer to the buffers directly
 */

 {
 float *d0,*d1,*d2,*d3;

 float *B = f->B[blocktype] + n2 - 8;
 float *e = buf2 + n2 - 8;
 d0 = &buffer[0];
 d1 = &buffer[n2-4];
 d2 = &buffer[n2];
 d3 = &buffer[n-4];
 while (e >= v) {
 float p0,p1,p2,p3;

 p3 = e[6]*B[7] - e[7]*B[6];
 p2 = -e[6]*B[6] - e[7]*B[7];

 d0[0] = p3;
 d1[3] = - p3;
 d2[0] = p2;
 d3[3] = p2;

 p1 = e[4]*B[5] - e[5]*B[4];
 p0 = -e[4]*B[4] - e[5]*B[5];

 d0[1] = p1;
 d1[2] = - p1;
 d2[1] = p0;
 d3[2] = p0;

 p3 = e[2]*B[3] - e[3]*B[2];
 p2 = -e[2]*B[2] - e[3]*B[3];

 d0[2] = p3;
 d1[1] = - p3;
 d2[2] = p2;
 d3[1] = p2;

 p1 = e[0]*B[1] - e[1]*B[0];
 p0 = -e[0]*B[0] - e[1]*B[1];

 d0[3] = p1;
 d1[0] = - p1;
 d2[3] = p0;
 d3[0] = p0;

 B -= 8;
 e -= 8;
 d0 += 4;
 d2 += 4;
 d1 -= 4;
 d3 -= 4;
 }
 }

 temp_alloc_restore(f,save_point);
}

static float *get_window(vorb *f, int len)
{
 len <<= 1;
 if (len == f->blocksize_0) return f->window[0];
 if (len == f->blocksize_1) return f->window[1];
 assert(0);
 return NULL;
}

typedef int16_t YTYPE;

static int do_floor(vorb *f, Mapping *map, int i, int n, float *target, YTYPE *finalY, uint8_t *step2_flag)
{
 int n2 = n >> 1;
 int s = map->chan[i].mux, floor;
 floor = map->submap_floor[s];
 if (f->floor_types[floor] == 0) {
 return error(f, VORBIS_invalid_stream);
 } else {
 Floor1 *g = &f->floor_config[floor].floor1;
 int j,q;
 int lx = 0, ly = finalY[0] * g->floor1_multiplier;
 for (q=1; q < g->values; ++q) {
 j = g->sorted_order[q];
 if (finalY[j] >= 0)
 {
 int hy = finalY[j] * g->floor1_multiplier;
 int hx = g->Xlist[j];
 draw_line(target, lx,ly, hx,hy, n2);
 lx = hx, ly = hy;
 }
 }
 if (lx < n2)
 /* optimization of: draw_line(target, lx,ly, n,ly, n2); */
 for (j=lx; j < n2; ++j)
 LINE_OP(target[j], inverse_db_table[ly]);
 }
 return TRUE;
}

static int vorbis_decode_initial(vorb *f, int *p_left_start, int *p_left_end, int *p_right_start, int *p_right_end, int *mode)
{
 Mode *m;
 int i, n, prev, next, window_center;
 f->channel_buffer_start = f->channel_buffer_end = 0;

 retry:
 if (f->eof) return FALSE;
 if (!maybe_start_packet(f))
 return FALSE;
 /* check packet type */
 if (get_bits(f,1) != 0) {
 if (IS_PUSH_MODE(f))
 return error(f,VORBIS_bad_packet_type);
 while (EOP != get8_packet(f));
 goto retry;
 }

 if (f->alloc.alloc_buffer)
 assert(f->alloc.alloc_buffer_length_in_bytes == f->temp_offset);

 i = get_bits(f, ilog(f->mode_count-1));
 if (i == EOP) return FALSE;
 if (i >= f->mode_count) return FALSE;
 *mode = i;
 m = f->mode_config + i;
 if (m->blockflag) {
 n = f->blocksize_1;
 prev = get_bits(f,1);
 next = get_bits(f,1);
 } else {
 prev = next = 0;
 n = f->blocksize_0;
 }

/* WINDOWING */

 window_center = n >> 1;
 if (m->blockflag && !prev) {
 *p_left_start = (n - f->blocksize_0) >> 2;
 *p_left_end = (n + f->blocksize_0) >> 2;
 } else {
 *p_left_start = 0;
 *p_left_end = window_center;
 }
 if (m->blockflag && !next) {
 *p_right_start = (n*3 - f->blocksize_0) >> 2;
 *p_right_end = (n*3 + f->blocksize_0) >> 2;
 } else {
 *p_right_start = window_center;
 *p_right_end = n;
 }
 return TRUE;
}

static int vorbis_decode_packet_rest(vorb *f, int *len, Mode *m, int left_start, int left_end, int right_start, int right_end, int *p_left)
{
 Mapping *map;
 int i,j,k,n,n2;
 int zero_channel[256];
 int really_zero_channel[256];

/* WINDOWING */

 n = f->blocksize[m->blockflag];
 map = &f->mapping[m->mapping];

/* FLOORS */
 n2 = n >> 1;

 for (i=0; i < f->channels; ++i) {
 int s = map->chan[i].mux, floor;
 zero_channel[i] = FALSE;
 floor = map->submap_floor[s];
 if (f->floor_types[floor] == 0) {
 return error(f, VORBIS_invalid_stream);
 } else {
 Floor1 *g = &f->floor_config[floor].floor1;
 if (get_bits(f, 1)) {
 short *finalY;
 uint8_t step2_flag[256];
 static int range_list[4] = { 256, 128, 86, 64 };
 int range = range_list[g->floor1_multiplier-1];
 int offset = 2;
 finalY = f->finalY[i];
 finalY[0] = get_bits(f, ilog(range)-1);
 finalY[1] = get_bits(f, ilog(range)-1);
 for (j=0; j < g->partitions; ++j) {
 int pclass = g->partition_class_list[j];
 int cdim = g->class_dimensions[pclass];
 int cbits = g->class_subclasses[pclass];
 int csub = (1 << cbits)-1;
 int cval = 0;
 if (cbits) {
 Codebook *c = f->codebooks + g->class_masterbooks[pclass];
 DECODE(cval,f,c);
 }
 for (k=0; k < cdim; ++k) {
 int book = g->subclass_books[pclass][cval & csub];
 cval = cval >> cbits;
 if (book >= 0) {
 int temp;
 Codebook *c = f->codebooks + book;
 DECODE(temp,f,c);
 finalY[offset++] = temp;
 } else
 finalY[offset++] = 0;
 }
 }
 if (f->valid_bits == INVALID_BITS) goto error; /* behavior according to spec */
 step2_flag[0] = step2_flag[1] = 1;
 for (j=2; j < g->values; ++j) {
 int low, high, pred, highroom, lowroom, room, val;
 low = g->neighbors[j][0];
 high = g->neighbors[j][1];
#if 0
 neighbors(g->Xlist, j, &low, &high);
#endif
 pred = predict_point(g->Xlist[j], g->Xlist[low], g->Xlist[high], finalY[low], finalY[high]);
 val = finalY[j];
 highroom = range - pred;
 lowroom = pred;
 if (highroom < lowroom)
 room = highroom * 2;
 else
 room = lowroom * 2;
 if (val) {
 step2_flag[low] = step2_flag[high] = 1;
 step2_flag[j] = 1;
 if (val >= room)
 if (highroom > lowroom)
 finalY[j] = val - lowroom + pred;
 else
 finalY[j] = pred - val + highroom - 1;
 else
 if (val & 1)
 finalY[j] = pred - ((val+1)>>1);
 else
 finalY[j] = pred + (val>>1);
 } else {
 step2_flag[j] = 0;
 finalY[j] = pred;
 }
 }

 /* defer final floor computation until _after_ residue */
 for (j=0; j < g->values; ++j) {
 if (!step2_flag[j])
 finalY[j] = -1;
 }
 } else {
 error:
 zero_channel[i] = TRUE;
 }
 /* So we just defer everything else to later */

 /* at this point we've decoded the floor into buffer */
 }
 }
 /* at this point we've decoded all floors */

 if (f->alloc.alloc_buffer)
 assert(f->alloc.alloc_buffer_length_in_bytes == f->temp_offset);

 /* re-enable coupled channels if necessary */
 memcpy(really_zero_channel, zero_channel, sizeof(really_zero_channel[0]) * f->channels);
 for (i=0; i < map->coupling_steps; ++i)
 if (!zero_channel[map->chan[i].magnitude] || !zero_channel[map->chan[i].angle]) {
 zero_channel[map->chan[i].magnitude] = zero_channel[map->chan[i].angle] = FALSE;
 }

/* RESIDUE DECODE */
 for (i=0; i < map->submaps; ++i) {
 float *residue_buffers[STB_VORBIS_MAX_CHANNELS];
 int r;
 uint8_t do_not_decode[256] = {0};
 int ch = 0;
 for (j=0; j < f->channels; ++j) {
 if (map->chan[j].mux == i) {
 if (zero_channel[j]) {
 do_not_decode[ch] = TRUE;
 residue_buffers[ch] = NULL;
 } else {
 do_not_decode[ch] = FALSE;
 residue_buffers[ch] = f->channel_buffers[j];
 }
 ++ch;
 }
 }
 r = map->submap_residue[i];
 decode_residue(f, residue_buffers, ch, n2, r, do_not_decode);
 }

 if (f->alloc.alloc_buffer)
 assert(f->alloc.alloc_buffer_length_in_bytes == f->temp_offset);

/* INVERSE COUPLING */
 for (i = map->coupling_steps-1; i >= 0; --i) {
 int n2 = n >> 1;
 float *m = f->channel_buffers[map->chan[i].magnitude];
 float *a = f->channel_buffers[map->chan[i].angle ];
 for (j=0; j < n2; ++j) {
 float a2,m2;
 if (m[j] > 0)
 if (a[j] > 0)
 m2 = m[j], a2 = m[j] - a[j];
 else
 a2 = m[j], m2 = m[j] + a[j];
 else
 if (a[j] > 0)
 m2 = m[j], a2 = m[j] + a[j];
 else
 a2 = m[j], m2 = m[j] - a[j];
 m[j] = m2;
 a[j] = a2;
 }
 }

 /* finish decoding the floors */
 for (i=0; i < f->channels; ++i) {
 if (really_zero_channel[i]) {
 memset(f->channel_buffers[i], 0, sizeof(*f->channel_buffers[i]) * n2);
 } else {
 do_floor(f, map, i, n, f->channel_buffers[i], f->finalY[i], NULL);
 }
 }

/* INVERSE MDCT */
 for (i=0; i < f->channels; ++i)
 inverse_mdct(f->channel_buffers[i], n, f, m->blockflag);

 /* this shouldn't be necessary, unless we exited on an error
 * and want to flush to get to the next packet */
 flush_packet(f);

 if (f->first_decode) {
 /* assume we start so first non-discarded sample is sample 0
 * this isn't to spec, but spec would require us to read ahead
 * and decode the size of all current frames--could be done,
 * but presumably it's not a commonly used feature */
 f->current_loc = -n2; /* start of first frame is positioned for discard */
 /* we might have to discard samples "from" the next frame too,
 * if we're lapping a large block then a small at the start? */
 f->discard_samples_deferred = n - right_end;
 f->current_loc_valid = TRUE;
 f->first_decode = FALSE;
 } else if (f->discard_samples_deferred) {
 left_start += f->discard_samples_deferred;
 *p_left = left_start;
 f->discard_samples_deferred = 0;
 } else if (f->previous_length == 0 && f->current_loc_valid) {
 /* we're recovering from a seek... that means we're going to discard
 * the samples from this packet even though we know our position from
 * the last page header, so we need to update the position based on
 * the discarded samples here
 * but wait, the code below is going to add this in itself even
 * on a discard, so we don't need to do it here... */
 }

 /* check if we have ogg information about the sample # for this packet */
 if (f->last_seg_which == f->end_seg_with_known_loc) {
 /* if we have a valid current loc, and this is final: */
 if (f->current_loc_valid && (f->page_flag & PAGEFLAG_last_page)) {
 uint32_t current_end = f->known_loc_for_packet - (n-right_end);
 /* then let's infer the size of the (probably) short final frame */
 if (current_end < f->current_loc + right_end) {
 if (current_end < f->current_loc) {
 /* negative truncation, that's impossible! */
 *len = 0;
 } else {
 *len = current_end - f->current_loc;
 }
 *len += left_start;
 f->current_loc += *len;
 return TRUE;
 }
 }
 /* otherwise, just set our sample loc
 * guess that the ogg granule pos refers to the _middle_ of the
 * last frame?
 * set f->current_loc to the position of left_start */
 f->current_loc = f->known_loc_for_packet - (n2-left_start);
 f->current_loc_valid = TRUE;
 }
 if (f->current_loc_valid)
 f->current_loc += (right_start - left_start);

 if (f->alloc.alloc_buffer)
 assert(f->alloc.alloc_buffer_length_in_bytes == f->temp_offset);
 *len = right_end; /* ignore samples after the window goes to 0 */
 return TRUE;
}

static int vorbis_decode_packet(vorb *f, int *len, int *p_left, int *p_right)
{
 int mode, left_end, right_end;
 if (!vorbis_decode_initial(f, p_left, &left_end, p_right, &right_end, &mode)) return 0;
 return vorbis_decode_packet_rest(f, len, f->mode_config + mode, *p_left, left_end, *p_right, right_end, p_left);
}

static int vorbis_finish_frame(stb_vorbis *f, int len, int left, int right)
{
 int prev,i,j;
 /* we use right&left (the start of the right- and left-window sin()-regions)
 * to determine how much to return, rather than inferring from the rules
 * (same result, clearer code); 'left' indicates where our sin() window
 * starts, therefore where the previous window's right edge starts, and
 * therefore where to start mixing from the previous buffer. 'right'
 * indicates where our sin() ending-window starts, therefore that's where
 * we start saving, and where our returned-data ends.

 * mixin from previous window */
 if (f->previous_length) {
 int i,j, n = f->previous_length;
 float *w = get_window(f, n);
 for (i=0; i < f->channels; ++i) {
 for (j=0; j < n; ++j)
 f->channel_buffers[i][left+j] =
 f->channel_buffers[i][left+j]*w[ j] +
 f->previous_window[i][ j]*w[n-1-j];
 }
 }

 prev = f->previous_length;

 /* last half of this data becomes previous window */
 f->previous_length = len - right;

 /* @OPTIMIZE: could avoid this copy by double-buffering the
 * output (flipping previous_window with channel_buffers), but
 * then previous_window would have to be 2x as large, and
 * channel_buffers couldn't be temp mem (although they're NOT
 * currently temp mem, they could be (unless we want to level
 * performance by spreading out the computation)) */
 for (i=0; i < f->channels; ++i)
 for (j=0; right+j < len; ++j)
 f->previous_window[i][j] = f->channel_buffers[i][right+j];

 if (!prev)
 /* there was no previous packet, so this data isn't valid...
 * this isn't entirely true, only the would-have-overlapped data
 * isn't valid, but this seems to be what the spec requires */
 return 0;

 /* truncate a short frame */
 if (len < right) right = len;

 f->samples_output += right-left;

 return right - left;
}

static void vorbis_pump_first_frame(stb_vorbis *f)
{
 int len, right, left;
 if (vorbis_decode_packet(f, &len, &left, &right))
 vorbis_finish_frame(f, len, left, right);
}

static int start_decoder(vorb *f)
{
 uint8_t header[6], x,y;
 int len,i,j,k, max_submaps = 0;
 int longest_floorlist=0;

 /* first page, first packet */

 if (!start_page(f)) return FALSE;
 /* validate page flag */
 if (!(f->page_flag & PAGEFLAG_first_page)) return error(f, VORBIS_invalid_first_page);
 if (f->page_flag & PAGEFLAG_last_page) return error(f, VORBIS_invalid_first_page);
 if (f->page_flag & PAGEFLAG_continued_packet) return error(f, VORBIS_invalid_first_page);
 /* check for expected packet length */
 if (f->segment_count != 1) return error(f, VORBIS_invalid_first_page);
 if (f->segments[0] != 30) return error(f, VORBIS_invalid_first_page);
 /* read packet
 * check packet header */
 if (get8(f) != VORBIS_packet_id) return error(f, VORBIS_invalid_first_page);
 if (!getn(f, header, 6)) return error(f, VORBIS_unexpected_eof);
 if (!vorbis_validate(header)) return error(f, VORBIS_invalid_first_page);
 /* vorbis_version */
 if (get32(f) != 0) return error(f, VORBIS_invalid_first_page);
 f->channels = get8(f); if (!f->channels) return error(f, VORBIS_invalid_first_page);
 if (f->channels > STB_VORBIS_MAX_CHANNELS) return error(f, VORBIS_too_many_channels);
 f->sample_rate = get32(f); if (!f->sample_rate) return error(f, VORBIS_invalid_first_page);
 get32(f); /* bitrate_maximum */
 get32(f); /* bitrate_nominal */
 get32(f); /* bitrate_minimum */
 x = get8(f);
 { int log0,log1;
 log0 = x & 15;
 log1 = x >> 4;
 f->blocksize_0 = 1 << log0;
 f->blocksize_1 = 1 << log1;
 if (log0 < 6 || log0 > 13) return error(f, VORBIS_invalid_setup);
 if (log1 < 6 || log1 > 13) return error(f, VORBIS_invalid_setup);
 if (log0 > log1) return error(f, VORBIS_invalid_setup);
 }

 /* framing_flag */
 x = get8(f);
 if (!(x & 1)) return error(f, VORBIS_invalid_first_page);

 /* second packet! */
 if (!start_page(f)) return FALSE;

 if (!start_packet(f)) return FALSE;
 do {
 len = next_segment(f);
 skip(f, len);
 f->bytes_in_seg = 0;
 } while (len);

 /* third packet! */
 if (!start_packet(f)) return FALSE;

 crc32_init(); /* always init it, to avoid multithread race conditions */

 if (get8_packet(f) != VORBIS_packet_setup) return error(f, VORBIS_invalid_setup);
 for (i=0; i < 6; ++i) header[i] = get8_packet(f);
 if (!vorbis_validate(header)) return error(f, VORBIS_invalid_setup);

 /* codebooks */

 f->codebook_count = get_bits(f,8) + 1;
 f->codebooks = (Codebook *) setup_malloc(f, sizeof(*f->codebooks) * f->codebook_count);
 if (f->codebooks == NULL) return error(f, VORBIS_outofmem);
 memset(f->codebooks, 0, sizeof(*f->codebooks) * f->codebook_count);
 for (i=0; i < f->codebook_count; ++i) {
 uint32_t *values;
 int ordered, sorted_count;
 int total=0;
 uint8_t *lengths;
 Codebook *c = f->codebooks+i;
 x = get_bits(f, 8); if (x != 0x42) return error(f, VORBIS_invalid_setup);
 x = get_bits(f, 8); if (x != 0x43) return error(f, VORBIS_invalid_setup);
 x = get_bits(f, 8); if (x != 0x56) return error(f, VORBIS_invalid_setup);
 x = get_bits(f, 8);
 c->dimensions = (get_bits(f, 8)<<8) + x;
 x = get_bits(f, 8);
 y = get_bits(f, 8);
 c->entries = (get_bits(f, 8)<<16) + (y<<8) + x;
 ordered = get_bits(f,1);
 c->sparse = ordered ? 0 : get_bits(f,1);

 if (c->sparse)
 lengths = (uint8_t *) setup_temp_malloc(f, c->entries);
 else
 lengths = c->codeword_lengths = (uint8_t *) setup_malloc(f, c->entries);

 if (!lengths) return error(f, VORBIS_outofmem);

 if (ordered) {
 int current_entry = 0;
 int current_length = get_bits(f,5) + 1;
 while (current_entry < c->entries) {
 int limit = c->entries - current_entry;
 int n = get_bits(f, ilog(limit));
 if (current_entry + n > (int) c->entries) { return error(f, VORBIS_invalid_setup); }
 memset(lengths + current_entry, current_length, n);
 current_entry += n;
 ++current_length;
 }
 } else {
 for (j=0; j < c->entries; ++j) {
 int present = c->sparse ? get_bits(f,1) : 1;
 if (present) {
 lengths[j] = get_bits(f, 5) + 1;
 ++total;
 } else {
 lengths[j] = NO_CODE;
 }
 }
 }

 if (c->sparse && total >= c->entries >> 2) {
 /* convert sparse items to non-sparse! */
 if (c->entries > (int) f->setup_temp_memory_required)
 f->setup_temp_memory_required = c->entries;

 c->codeword_lengths = (uint8_t *) setup_malloc(f, c->entries);
 memcpy(c->codeword_lengths, lengths, c->entries);
 setup_temp_free(f, lengths, c->entries); /* note this is only safe if there have been no intervening temp mallocs! */
 lengths = c->codeword_lengths;
 c->sparse = 0;
 }

 /* compute the size of the sorted tables */
 if (c->sparse) {
 sorted_count = total;
 } else {
 sorted_count = 0;
 #ifndef STB_VORBIS_NO_HUFFMAN_BINARY_SEARCH
 for (j=0; j < c->entries; ++j)
 if (lengths[j] > STB_VORBIS_FAST_HUFFMAN_LENGTH && lengths[j] != NO_CODE)
 ++sorted_count;
 #endif
 }

 c->sorted_entries = sorted_count;
 values = NULL;

 if (!c->sparse) {
 c->codewords = (uint32_t *) setup_malloc(f, sizeof(c->codewords[0]) * c->entries);
 if (!c->codewords) return error(f, VORBIS_outofmem);
 } else {
 unsigned int size;
 if (c->sorted_entries) {
 c->codeword_lengths = (uint8_t *) setup_malloc(f, c->sorted_entries);
 if (!c->codeword_lengths) return error(f, VORBIS_outofmem);
 c->codewords = (uint32_t *) setup_temp_malloc(f, sizeof(*c->codewords) * c->sorted_entries);
 if (!c->codewords) return error(f, VORBIS_outofmem);
 values = (uint32_t *) setup_temp_malloc(f, sizeof(*values) * c->sorted_entries);
 if (!values) return error(f, VORBIS_outofmem);
 }
 size = c->entries + (sizeof(*c->codewords) + sizeof(*values)) * c->sorted_entries;
 if (size > f->setup_temp_memory_required)
 f->setup_temp_memory_required = size;
 }

 if (!compute_codewords(c, lengths, c->entries, values)) {
 if (c->sparse) setup_temp_free(f, values, 0);
 return error(f, VORBIS_invalid_setup);
 }

 if (c->sorted_entries) {
 /* allocate an extra slot for sentinels */
 c->sorted_codewords = (uint32_t *) setup_malloc(f, sizeof(*c->sorted_codewords) * (c->sorted_entries+1));
 /* allocate an extra slot at the front so that c->sorted_values[-1] is defined
 * so that we can catch that case without an extra if */
 c->sorted_values = ( int *) setup_malloc(f, sizeof(*c->sorted_values ) * (c->sorted_entries+1));
 if (c->sorted_values) { ++c->sorted_values; c->sorted_values[-1] = -1; }
 compute_sorted_huffman(c, lengths, values);
 }

 if (c->sparse) {
 setup_temp_free(f, values, sizeof(*values)*c->sorted_entries);
 setup_temp_free(f, c->codewords, sizeof(*c->codewords)*c->sorted_entries);
 setup_temp_free(f, lengths, c->entries);
 c->codewords = NULL;
 }

 compute_accelerated_huffman(c);

 c->lookup_type = get_bits(f, 4);
 if (c->lookup_type > 2) return error(f, VORBIS_invalid_setup);
 if (c->lookup_type > 0) {
 uint16_t *mults;
 c->minimum_value = float32_unpack(get_bits(f, 32));
 c->delta_value = float32_unpack(get_bits(f, 32));
 c->value_bits = get_bits(f, 4)+1;
 c->sequence_p = get_bits(f,1);
 if (c->lookup_type == 1) {
 c->lookup_values = lookup1_values(c->entries, c->dimensions);
 } else {
 c->lookup_values = c->entries * c->dimensions;
 }
 mults = (uint16_t *) setup_temp_malloc(f, sizeof(mults[0]) * c->lookup_values);
 if (mults == NULL) return error(f, VORBIS_outofmem);
 for (j=0; j < (int) c->lookup_values; ++j) {
 int q = get_bits(f, c->value_bits);
 if (q == EOP) { setup_temp_free(f,mults,sizeof(mults[0])*c->lookup_values); return error(f, VORBIS_invalid_setup); }
 mults[j] = q;
 }

 if (c->lookup_type == 1) {
 int len, sparse = c->sparse;
 /* pre-expand the lookup1-style multiplicands, to avoid a divide in the inner loop */
 if (sparse) {
 if (c->sorted_entries == 0) goto skip;
 c->multiplicands = (stb_vorbis_codetype *) setup_malloc(f, sizeof(c->multiplicands[0]) * c->sorted_entries * c->dimensions);
 } else
 c->multiplicands = (stb_vorbis_codetype *) setup_malloc(f, sizeof(c->multiplicands[0]) * c->entries * c->dimensions);
 if (c->multiplicands == NULL) { setup_temp_free(f,mults,sizeof(mults[0])*c->lookup_values); return error(f, VORBIS_outofmem); }
 len = sparse ? c->sorted_entries : c->entries;
 for (j=0; j < len; ++j) {
 int z = sparse ? c->sorted_values[j] : j, div=1;
 for (k=0; k < c->dimensions; ++k) {
 int off = (z / div) % c->lookup_values;
 c->multiplicands[j*c->dimensions + k] =
 #ifndef STB_VORBIS_CODEBOOK_FLOATS
 mults[off];
 #else
 mults[off]*c->delta_value + c->minimum_value;
 /* in this case (and this case only) we could pre-expand c->sequence_p,
 * and throw away the decode logic for it; have to ALSO do
 * it in the case below, but it can only be done if
 * STB_VORBIS_CODEBOOK_FLOATS */
 #endif
 div *= c->lookup_values;
 }
 }
 setup_temp_free(f, mults,sizeof(mults[0])*c->lookup_values);
 c->lookup_type = 2;
 }
 else
 {
 c->multiplicands = (stb_vorbis_codetype *) setup_malloc(f, sizeof(c->multiplicands[0]) * c->lookup_values);
 #ifndef STB_VORBIS_CODEBOOK_FLOATS
 memcpy(c->multiplicands, mults, sizeof(c->multiplicands[0]) * c->lookup_values);
 #else
 for (j=0; j < (int) c->lookup_values; ++j)
 c->multiplicands[j] = mults[j] * c->delta_value + c->minimum_value;
 #endif
 setup_temp_free(f, mults,sizeof(mults[0])*c->lookup_values);
 }
 skip:;

 #ifdef STB_VORBIS_CODEBOOK_FLOATS
 if (c->lookup_type == 2 && c->sequence_p) {
 for (j=1; j < (int) c->lookup_values; ++j)
 c->multiplicands[j] = c->multiplicands[j-1];
 c->sequence_p = 0;
 }
 #endif
 }
 }

 /* time domain transfers (notused) */

 x = get_bits(f, 6) + 1;
 for (i=0; i < x; ++i) {
 uint32_t z = get_bits(f, 16);
 if (z != 0) return error(f, VORBIS_invalid_setup);
 }

 /* Floors */
 f->floor_count = get_bits(f, 6)+1;
 f->floor_config = (Floor *) setup_malloc(f, f->floor_count * sizeof(*f->floor_config));
 for (i=0; i < f->floor_count; ++i) {
 f->floor_types[i] = get_bits(f, 16);
 if (f->floor_types[i] > 1) return error(f, VORBIS_invalid_setup);
 if (f->floor_types[i] == 0) {
 Floor0 *g = &f->floor_config[i].floor0;
 g->order = get_bits(f,8);
 g->rate = get_bits(f,16);
 g->bark_map_size = get_bits(f,16);
 g->amplitude_bits = get_bits(f,6);
 g->amplitude_offset = get_bits(f,8);
 g->number_of_books = get_bits(f,4) + 1;
 for (j=0; j < g->number_of_books; ++j)
 g->book_list[j] = get_bits(f,8);
 return error(f, VORBIS_feature_not_supported);
 } else {
 STBV_Point p[31*8+2];
 Floor1 *g = &f->floor_config[i].floor1;
 int max_class = -1;
 g->partitions = get_bits(f, 5);
 for (j=0; j < g->partitions; ++j) {
 g->partition_class_list[j] = get_bits(f, 4);
 if (g->partition_class_list[j] > max_class)
 max_class = g->partition_class_list[j];
 }
 for (j=0; j <= max_class; ++j) {
 g->class_dimensions[j] = get_bits(f, 3)+1;
 g->class_subclasses[j] = get_bits(f, 2);
 if (g->class_subclasses[j]) {
 g->class_masterbooks[j] = get_bits(f, 8);
 if (g->class_masterbooks[j] >= f->codebook_count) return error(f, VORBIS_invalid_setup);
 }
 for (k=0; k < 1 << g->class_subclasses[j]; ++k) {
 g->subclass_books[j][k] = get_bits(f,8)-1;
 if (g->subclass_books[j][k] >= f->codebook_count) return error(f, VORBIS_invalid_setup);
 }
 }
 g->floor1_multiplier = get_bits(f,2)+1;
 g->rangebits = get_bits(f,4);
 g->Xlist[0] = 0;
 g->Xlist[1] = 1 << g->rangebits;
 g->values = 2;
 for (j=0; j < g->partitions; ++j) {
 int c = g->partition_class_list[j];
 for (k=0; k < g->class_dimensions[c]; ++k) {
 g->Xlist[g->values] = get_bits(f, g->rangebits);
 ++g->values;
 }
 }
 /* precompute the sorting */
 for (j=0; j < g->values; ++j) {
 p[j].x = g->Xlist[j];
 p[j].y = j;
 }
 qsort(p, g->values, sizeof(p[0]), point_compare);
 for (j=0; j < g->values; ++j)
 g->sorted_order[j] = (uint8_t) p[j].y;
 /* precompute the neighbors */
 for (j=2; j < g->values; ++j)
 {
 int low = 0;
 int hi = 0;
 neighbors(g->Xlist, j, &low,&hi);
 g->neighbors[j][0] = low;
 g->neighbors[j][1] = hi;
 }

 if (g->values > longest_floorlist)
 longest_floorlist = g->values;
 }
 }

 /* Residue */
 f->residue_count = get_bits(f, 6)+1;
 f->residue_config = (Residue *) setup_malloc(f, f->residue_count * sizeof(*f->residue_config));
 for (i=0; i < f->residue_count; ++i) {
 uint8_t residue_cascade[64];
 Residue *r = f->residue_config+i;
 f->residue_types[i] = get_bits(f, 16);
 if (f->residue_types[i] > 2) return error(f, VORBIS_invalid_setup);
 r->begin = get_bits(f, 24);
 r->end = get_bits(f, 24);
 r->part_size = get_bits(f,24)+1;
 r->classifications = get_bits(f,6)+1;
 r->classbook = get_bits(f,8);
 for (j=0; j < r->classifications; ++j) {
 uint8_t high_bits=0;
 uint8_t low_bits=get_bits(f,3);
 if (get_bits(f,1))
 high_bits = get_bits(f,5);
 residue_cascade[j] = high_bits*8 + low_bits;
 }
 r->residue_books = (short (*)[8]) setup_malloc(f, sizeof(r->residue_books[0]) * r->classifications);
 for (j=0; j < r->classifications; ++j) {
 for (k=0; k < 8; ++k) {
 if (residue_cascade[j] & (1 << k)) {
 r->residue_books[j][k] = get_bits(f, 8);
 if (r->residue_books[j][k] >= f->codebook_count) return error(f, VORBIS_invalid_setup);
 } else {
 r->residue_books[j][k] = -1;
 }
 }
 }
 /* precompute the classifications[] array to avoid inner-loop mod/divide
 * call it 'classdata' since we already have r->classifications */
 r->classdata = (uint8_t **) setup_malloc(f, sizeof(*r->classdata) * f->codebooks[r->classbook].entries);
 if (!r->classdata) return error(f, VORBIS_outofmem);
 memset(r->classdata, 0, sizeof(*r->classdata) * f->codebooks[r->classbook].entries);
 for (j=0; j < f->codebooks[r->classbook].entries; ++j) {
 int classwords = f->codebooks[r->classbook].dimensions;
 int temp = j;
 r->classdata[j] = (uint8_t *) setup_malloc(f, sizeof(r->classdata[j][0]) * classwords);
 for (k=classwords-1; k >= 0; --k) {
 r->classdata[j][k] = temp % r->classifications;
 temp /= r->classifications;
 }
 }
 }

 f->mapping_count = get_bits(f,6)+1;
 f->mapping = (Mapping *) setup_malloc(f, f->mapping_count * sizeof(*f->mapping));
 for (i=0; i < f->mapping_count; ++i) {
 Mapping *m = f->mapping + i;
 int mapping_type = get_bits(f,16);
 if (mapping_type != 0) return error(f, VORBIS_invalid_setup);
 m->chan = (MappingChannel *) setup_malloc(f, f->channels * sizeof(*m->chan));
 if (get_bits(f,1))
 m->submaps = get_bits(f,4)+1;
 else
 m->submaps = 1;
 if (m->submaps > max_submaps)
 max_submaps = m->submaps;
 if (get_bits(f,1)) {
 m->coupling_steps = get_bits(f,8)+1;
 for (k=0; k < m->coupling_steps; ++k) {
 m->chan[k].magnitude = get_bits(f, ilog(f->channels-1));
 m->chan[k].angle = get_bits(f, ilog(f->channels-1));
 if (m->chan[k].magnitude >= f->channels) return error(f, VORBIS_invalid_setup);
 if (m->chan[k].angle >= f->channels) return error(f, VORBIS_invalid_setup);
 if (m->chan[k].magnitude == m->chan[k].angle) return error(f, VORBIS_invalid_setup);
 }
 } else
 m->coupling_steps = 0;

 /* reserved field */
 if (get_bits(f,2)) return error(f, VORBIS_invalid_setup);
 if (m->submaps > 1) {
 for (j=0; j < f->channels; ++j) {
 m->chan[j].mux = get_bits(f, 4);
 if (m->chan[j].mux >= m->submaps) return error(f, VORBIS_invalid_setup);
 }
 } else
 /* @SPECIFICATION: this case is missing from the spec */
 for (j=0; j < f->channels; ++j)
 m->chan[j].mux = 0;

 for (j=0; j < m->submaps; ++j) {
 get_bits(f,8); /* discard */
 m->submap_floor[j] = get_bits(f,8);
 m->submap_residue[j] = get_bits(f,8);
 if (m->submap_floor[j] >= f->floor_count) return error(f, VORBIS_invalid_setup);
 if (m->submap_residue[j] >= f->residue_count) return error(f, VORBIS_invalid_setup);
 }
 }

 /* Modes */
 f->mode_count = get_bits(f, 6)+1;
 for (i=0; i < f->mode_count; ++i) {
 Mode *m = f->mode_config+i;
 m->blockflag = get_bits(f,1);
 m->windowtype = get_bits(f,16);
 m->transformtype = get_bits(f,16);
 m->mapping = get_bits(f,8);
 if (m->windowtype != 0) return error(f, VORBIS_invalid_setup);
 if (m->transformtype != 0) return error(f, VORBIS_invalid_setup);
 if (m->mapping >= f->mapping_count) return error(f, VORBIS_invalid_setup);
 }

 flush_packet(f);

 f->previous_length = 0;

 for (i=0; i < f->channels; ++i) {
 f->channel_buffers[i] = (float *) setup_malloc(f, sizeof(float) * f->blocksize_1);
 f->previous_window[i] = (float *) setup_malloc(f, sizeof(float) * f->blocksize_1/2);
 f->finalY[i] = (int16_t *) setup_malloc(f, sizeof(int16_t) * longest_floorlist);
 }

 if (!init_blocksize(f, 0, f->blocksize_0)) return FALSE;
 if (!init_blocksize(f, 1, f->blocksize_1)) return FALSE;
 f->blocksize[0] = f->blocksize_0;
 f->blocksize[1] = f->blocksize_1;

 /* compute how much temporary memory is needed */

 /* 1. */
 {
 uint32_t imdct_mem = (f->blocksize_1 * sizeof(float) >> 1);
 uint32_t classify_mem;
 int i,max_part_read=0;
 for (i=0; i < f->residue_count; ++i) {
 Residue *r = f->residue_config + i;
 int n_read = r->end - r->begin;
 int part_read = n_read / r->part_size;
 if (part_read > max_part_read)
 max_part_read = part_read;
 }
 classify_mem = f->channels * (sizeof(void*) + max_part_read * sizeof(uint8_t *));

 f->temp_memory_required = classify_mem;
 if (imdct_mem > f->temp_memory_required)
 f->temp_memory_required = imdct_mem;
 }

 f->first_decode = TRUE;

 if (f->alloc.alloc_buffer) {
 assert(f->temp_offset == f->alloc.alloc_buffer_length_in_bytes);
 /* check if there's enough temp memory so we don't error later */
 if (f->setup_offset + sizeof(*f) + f->temp_memory_required > (unsigned) f->temp_offset)
 return error(f, VORBIS_outofmem);
 }

 f->first_audio_page_offset = stb_vorbis_get_file_offset(f);

 return TRUE;
}

static void vorbis_deinit(stb_vorbis *p)
{
 int i,j;
 for (i=0; i < p->residue_count; ++i) {
 Residue *r = p->residue_config+i;
 if (r->classdata) {
 for (j=0; j < p->codebooks[r->classbook].entries; ++j)
 setup_free(p, r->classdata[j]);
 setup_free(p, r->classdata);
 }
 setup_free(p, r->residue_books);
 }

 if (p->codebooks) {
 for (i=0; i < p->codebook_count; ++i) {
 Codebook *c = p->codebooks + i;
 setup_free(p, c->codeword_lengths);
 setup_free(p, c->multiplicands);
 setup_free(p, c->codewords);
 setup_free(p, c->sorted_codewords);
 /* c->sorted_values[-1] is the first entry in the array */
 setup_free(p, c->sorted_values ? c->sorted_values-1 : NULL);
 }
 setup_free(p, p->codebooks);
 }
 setup_free(p, p->floor_config);
 setup_free(p, p->residue_config);
 for (i=0; i < p->mapping_count; ++i)
 setup_free(p, p->mapping[i].chan);
 setup_free(p, p->mapping);
 for (i=0; i < p->channels; ++i) {
 setup_free(p, p->channel_buffers[i]);
 setup_free(p, p->previous_window[i]);
 setup_free(p, p->finalY[i]);
 }
 for (i=0; i < 2; ++i) {
 setup_free(p, p->A[i]);
 setup_free(p, p->B[i]);
 setup_free(p, p->C[i]);
 setup_free(p, p->window[i]);
 setup_free(p, p->bit_reverse[i]);
 }
}

void stb_vorbis_close(stb_vorbis *p)
{
 if (p == NULL) return;
 vorbis_deinit(p);
 setup_free(p,p);
}

static void vorbis_init(stb_vorbis *p, stb_vorbis_alloc *z)
{
 memset(p, 0, sizeof(*p)); /* NULL out all malloc'd pointers to start */
 if (z) {
 p->alloc = *z;
 p->alloc.alloc_buffer_length_in_bytes = (p->alloc.alloc_buffer_length_in_bytes+3) & ~3;
 p->temp_offset = p->alloc.alloc_buffer_length_in_bytes;
 }
 p->eof = 0;
 p->error = VORBIS__no_error;
 p->stream = NULL;
 p->codebooks = NULL;
 p->page_crc_tests = -1;
}

int stb_vorbis_get_sample_offset(stb_vorbis *f)
{
 if (f->current_loc_valid)
 return f->current_loc;
 return -1;
}

stb_vorbis_info stb_vorbis_get_info(stb_vorbis *f)
{
 stb_vorbis_info d;
 d.channels = f->channels;
 d.sample_rate = f->sample_rate;
 d.setup_memory_required = f->setup_memory_required;
 d.setup_temp_memory_required = f->setup_temp_memory_required;
 d.temp_memory_required = f->temp_memory_required;
 d.max_frame_size = f->blocksize_1 >> 1;
 return d;
}

int stb_vorbis_get_error(stb_vorbis *f)
{
 int e = f->error;
 f->error = VORBIS__no_error;
 return e;
}

static stb_vorbis * vorbis_alloc(stb_vorbis *f)
{
 stb_vorbis *p = (stb_vorbis *) setup_malloc(f, sizeof(*p));
 return p;
}

unsigned int stb_vorbis_get_file_offset(stb_vorbis *f)
{
 return (unsigned int)(f->stream - f->stream_start);
}

#ifndef STB_VORBIS_NO_PULLDATA_API
/* DATA-PULLING API */

static uint32_t vorbis_find_page(stb_vorbis *f, uint32_t *end, uint32_t *last)
{
 for(;;) {
 int n;
 if (f->eof) return 0;
 n = get8(f);
 if (n == 0x4f) { /* page header */
 unsigned int retry_loc = stb_vorbis_get_file_offset(f);
 int i;
 /* check if we're off the end of a file_section stream */
 if (retry_loc - 25 > f->stream_len)
 return 0;
 /* check the rest of the header */
 for (i=1; i < 4; ++i)
 if (get8(f) != ogg_page_header[i])
 break;
 if (f->eof) return 0;
 if (i == 4) {
 uint8_t header[27];
 uint32_t i, crc, goal, len;
 for (i=0; i < 4; ++i)
 header[i] = ogg_page_header[i];
 for (; i < 27; ++i)
 header[i] = get8(f);
 if (f->eof) return 0;
 if (header[4] != 0) goto invalid;
 goal = header[22] + (header[23] << 8) + (header[24]<<16) + (header[25]<<24);
 for (i=22; i < 26; ++i)
 header[i] = 0;
 crc = 0;
 for (i=0; i < 27; ++i)
 crc = crc32_update(crc, header[i]);
 len = 0;
 for (i=0; i < header[26]; ++i) {
 int s = get8(f);
 crc = crc32_update(crc, s);
 len += s;
 }
 if (len && f->eof) return 0;
 for (i=0; i < len; ++i)
 crc = crc32_update(crc, get8(f));
 /* finished parsing probable page */
 if (crc == goal) {
 /* we could now check that it's either got the last
 * page flag set, OR it's followed by the capture
 * pattern, but I guess TECHNICALLY you could have
 * a file with garbage between each ogg page and recover
 * from it automatically? So even though that paranoia
 * might decrease the chance of an invalid decode by
 * another 2^32, not worth it since it would hose those
 * invalid-but-useful files? */
 if (end)
 *end = stb_vorbis_get_file_offset(f);
 if (last) {
 if (header[5] & 0x04)
 *last = 1;
 else
 *last = 0;
 }
 set_file_offset(f, retry_loc-1);
 return 1;
 }
 }
 invalid:
 /* not a valid page, so rewind and look for next one */
 set_file_offset(f, retry_loc);
 }
 }
}

/* seek is implemented with 'interpolation search'--this is like
 * binary search, but we use the data values to estimate the likely
 * location of the data item (plus a bit of a bias so when the
 * estimation is wrong we don't waste overly much time)
 */

#define SAMPLE_unknown 0xffffffff


/* ogg vorbis, in its insane infinite wisdom, only provides
 * information about the sample at the END of the page.
 * therefore we COULD have the data we need in the current
 * page, and not know it. we could just use the end location
 * as our only knowledge for bounds, seek back, and eventually
 * the binary search finds it. or we can try to be smart and
 * not waste time trying to locate more pages. we try to be
 * smart, since this data is already in memory anyway, so
 * doing needless I/O would be crazy!
 */
static int vorbis_analyze_page(stb_vorbis *f, ProbedPage *z)
{
 uint8_t lacing[255];
 uint8_t packet_type[255];
 int num_packet, packet_start;
 int i,len;
 uint32_t samples;
 uint8_t header[27] = {0};

 /* record where the page starts */
 z->page_start = stb_vorbis_get_file_offset(f);

 /* parse the header */
 getn(f, header, 27);
 assert(header[0] == 'O' && header[1] == 'g' && header[2] == 'g' && header[3] == 'S');
 getn(f, lacing, header[26]);

 /* determine the length of the payload */
 len = 0;
 for (i=0; i < header[26]; ++i)
 len += lacing[i];

 /* this implies where the page ends */
 z->page_end = z->page_start + 27 + header[26] + len;

 /* read the last-decoded sample out of the data */
 z->last_decoded_sample = header[6] + (header[7] << 8) + (header[8] << 16) + (header[9] << 16);

 if (header[5] & 4) {
 /* if this is the last page, it's not possible to work
 * backwards to figure out the first sample! whoops! fuck. */
 z->first_decoded_sample = SAMPLE_unknown;
 set_file_offset(f, z->page_start);
 return 1;
 }

 /* scan through the frames to determine the sample-count of each one...
 * our goal is the sample # of the first fully-decoded sample on the
 * page, which is the first decoded sample of the 2nd packet */

 num_packet=0;

 packet_start = ((header[5] & 1) == 0);

 for (i=0; i < header[26]; ++i) {
 if (packet_start) {
 uint8_t n,b;
 if (lacing[i] == 0) goto bail; /* trying to read from zero-length packet */
 n = get8(f);
 /* if bottom bit is non-zero, we've got corruption */
 if (n & 1) goto bail;
 n >>= 1;
 b = ilog(f->mode_count-1);
 n &= (1 << b)-1;
 if (n >= f->mode_count) goto bail;
 packet_type[num_packet++] = f->mode_config[n].blockflag;
 skip(f, lacing[i]-1);
 } else
 skip(f, lacing[i]);
 packet_start = (lacing[i] < 255);
 }

 /* now that we know the sizes of all the pages, we can start determining
 * how much sample data there is. */

 samples = 0;

 /* for the last packet, we step by its whole length, because the definition
 * is that we encoded the end sample loc of the 'last packet completed',
 * where 'completed' refers to packets being split, and we are left to guess
 * what 'end sample loc' means. we assume it means ignoring the fact that
 * the last half of the data is useless without windowing against the next
 * packet... (so it's not REALLY complete in that sense)
 */
 if (num_packet > 1)
 samples += f->blocksize[packet_type[num_packet-1]];

 for (i=num_packet-2; i >= 1; --i) {
 /* now, for this packet, how many samples do we have that
 * do not overlap the following packet? */
 if (packet_type[i] == 1)
 if (packet_type[i+1] == 1)
 samples += f->blocksize_1 >> 1;
 else
 samples += ((f->blocksize_1 - f->blocksize_0) >> 2) + (f->blocksize_0 >> 1);
 else
 samples += f->blocksize_0 >> 1;
 }
 /* now, at this point, we've rewound to the very beginning of the
 * _second_ packet. if we entirely discard the first packet after
 * a seek, this will be exactly the right sample number. HOWEVER!
 * we can't as easily compute this number for the LAST page. The
 * only way to get the sample offset of the LAST page is to use
 * the end loc from the previous page. But what that returns us
 * is _exactly_ the place where we get our first non-overlapped
 * sample. (I think. Stupid spec for being ambiguous.) So for
 * consistency it's better to do that here, too. However, that
 * will then require us to NOT discard all of the first frame we
 * decode, in some cases, which means an even weirder frame size
 * and extra code. what a fucking pain.

 * we're going to discard the first packet if we
 * start the seek here, so we don't care about it. (we could actually
 * do better; if the first packet is long, and the previous packet
 * is short, there's actually data in the first half of the first
 * packet that doesn't need discarding... but not worth paying the
 * effort of tracking that of that here and in the seeking logic)
 * except crap, if we infer it from the _previous_ packet's end
 * location, we DO need to use that definition... and we HAVE to
 * infer the start loc of the LAST packet from the previous packet's
 * end location. fuck you, ogg vorbis. */

 z->first_decoded_sample = z->last_decoded_sample - samples;

 /* restore file state to where we were */
 set_file_offset(f, z->page_start);
 return 1;

 /* restore file state to where we were */
 bail:
 set_file_offset(f, z->page_start);
 return 0;
}

static int vorbis_seek_frame_from_page(stb_vorbis *f, uint32_t page_start, uint32_t first_sample, uint32_t target_sample, int fine)
{
 int left_start, left_end, right_start, right_end, mode,i;
 int frame=0;
 uint32_t frame_start;
 int frames_to_skip, data_to_skip;

 /* first_sample is the sample # of the first sample that doesn't
 * overlap the previous page... note that this requires us to
 * _partially_ discard the first packet! bleh. */
 set_file_offset(f, page_start);

 f->next_seg = -1; /* force page resync */

 frame_start = first_sample;
 /* frame start is where the previous packet's last decoded sample
 * was, which corresponds to left_end... EXCEPT if the previous
 * packet was long and this packet is short? Probably a bug here.


 * now, we can start decoding frames... we'll only FAKE decode them,
 * until we find the frame that contains our sample; then we'll rewind,
 * and try again */
 for (;;) {
 int start;

 if (!vorbis_decode_initial(f, &left_start, &left_end, &right_start, &right_end, &mode))
 return error(f, VORBIS_seek_failed);

 if (frame == 0)
 start = left_end;
 else
 start = left_start;

 /* the window starts at left_start; the last valid sample we generate
 * before the next frame's window start is right_start-1 */
 if (target_sample < frame_start + right_start-start)
 break;

 flush_packet(f);
 if (f->eof)
 return error(f, VORBIS_seek_failed);

 frame_start += right_start - start;

 ++frame;
 }

 /* ok, at this point, the sample we want is contained in frame #'frame'

 * to decode frame #'frame' normally, we have to decode the
 * previous frame first... but if it's the FIRST frame of the page
 * we can't. if it's the first frame, it means it falls in the part
 * of the first frame that doesn't overlap either of the other frames.
 * so, if we have to handle that case for the first frame, we might
 * as well handle it for all of them, so: */
 if (target_sample > frame_start + (left_end - left_start)) {
 /* so what we want to do is go ahead and just immediately decode
 * this frame, but then make it so the next get_frame_float() uses
 * this already-decoded data? or do we want to go ahead and rewind,
 * and leave a flag saying to skip the first N data? let's do that
 */
 frames_to_skip = frame; /* if this is frame #1, skip 1 frame (#0) */
 data_to_skip = left_end - left_start;
 } else {
 /* otherwise, we want to skip frames 0, 1, 2, ... frame-2
 * (which means frame-2+1 total frames) then decode frame-1,
 * then leave frame pending */
 frames_to_skip = frame - 1;
 assert(frames_to_skip >= 0);
 data_to_skip = -1;
 }

 set_file_offset(f, page_start);
 f->next_seg = - 1; /* force page resync */

 for (i=0; i < frames_to_skip; ++i) {
 maybe_start_packet(f);
 flush_packet(f);
 }

 if (data_to_skip >= 0) {
 int i,j,n = f->blocksize_0 >> 1;
 f->discard_samples_deferred = data_to_skip;
 for (i=0; i < f->channels; ++i)
 for (j=0; j < n; ++j)
 f->previous_window[i][j] = 0;
 f->previous_length = n;
 frame_start += data_to_skip;
 } else {
 f->previous_length = 0;
 vorbis_pump_first_frame(f);
 }

 /* at this point, the NEXT decoded frame will generate the desired sample */
 if (fine) {
 /* so if we're doing sample accurate streaming, we want to go ahead and decode it! */
 if (target_sample != frame_start) {
 int n;
 stb_vorbis_get_frame_float(f, &n, NULL);
 assert(target_sample > frame_start);
 assert(f->channel_buffer_start + (int) (target_sample-frame_start) < f->channel_buffer_end);
 f->channel_buffer_start += (target_sample - frame_start);
 }
 }

 return 0;
}

static int vorbis_seek_base(stb_vorbis *f, unsigned int sample_number, int fine)
{
 ProbedPage p[2],q;
 if (IS_PUSH_MODE(f)) return error(f, VORBIS_invalid_api_mixing);

 /* do we know the location of the last page? */
 if (f->p_last.page_start == 0) {
 uint32_t z = stb_vorbis_stream_length_in_samples(f);
 if (z == 0) return error(f, VORBIS_cant_find_last_page);
 }

 p[0] = f->p_first;
 p[1] = f->p_last;

 if (sample_number >= f->p_last.last_decoded_sample)
 sample_number = f->p_last.last_decoded_sample-1;

 if (sample_number < f->p_first.last_decoded_sample) {
 vorbis_seek_frame_from_page(f, p[0].page_start, 0, sample_number, fine);
 return 0;
 } else {
 int attempts=0;
 while (p[0].page_end < p[1].page_start) {
 uint32_t probe;
 uint32_t start_offset, end_offset;
 uint32_t start_sample, end_sample;

 /* copy these into local variables so we can tweak them
 * if any are unknown */
 start_offset = p[0].page_end;
 end_offset = p[1].after_previous_page_start; /* an address known to seek to page p[1] */
 start_sample = p[0].last_decoded_sample;
 end_sample = p[1].last_decoded_sample;

 /* currently there is no such tweaking logic needed/possible? */
 if (start_sample == SAMPLE_unknown || end_sample == SAMPLE_unknown)
 return error(f, VORBIS_seek_failed);

 /* now we want to lerp between these for the target samples... */

 /* step 1: we need to bias towards the page start... */
 if (start_offset + 4000 < end_offset)
 end_offset -= 4000;

 /* now compute an interpolated search loc */
 probe = start_offset + (int) floor((float) (end_offset - start_offset) / (end_sample - start_sample) * (sample_number - start_sample));

 /* next we need to bias towards binary search...
 * code is a little wonky to allow for full 32-bit unsigned values */
 if (attempts >= 4) {
 uint32_t probe2 = start_offset + ((end_offset - start_offset) >> 1);
 if (attempts >= 8)
 probe = probe2;
 else if (probe < probe2)
 probe = probe + ((probe2 - probe) >> 1);
 else
 probe = probe2 + ((probe - probe2) >> 1);
 }
 ++attempts;

 set_file_offset(f, probe);
 if (!vorbis_find_page(f, NULL, NULL)) return error(f, VORBIS_seek_failed);
 if (!vorbis_analyze_page(f, &q)) return error(f, VORBIS_seek_failed);
 q.after_previous_page_start = probe;

 /* it's possible we've just found the last page again */
 if (q.page_start == p[1].page_start) {
 p[1] = q;
 continue;
 }

 if (sample_number < q.last_decoded_sample)
 p[1] = q;
 else
 p[0] = q;
 }

 if (p[0].last_decoded_sample <= sample_number && sample_number < p[1].last_decoded_sample) {
 vorbis_seek_frame_from_page(f, p[1].page_start, p[0].last_decoded_sample, sample_number, fine);
 return 0;
 }
 return error(f, VORBIS_seek_failed);
 }
}

int stb_vorbis_seek_frame(stb_vorbis *f, unsigned int sample_number)
{
 return vorbis_seek_base(f, sample_number, FALSE);
}

int stb_vorbis_seek(stb_vorbis *f, unsigned int sample_number)
{
 return vorbis_seek_base(f, sample_number, TRUE);
}

void stb_vorbis_seek_start(stb_vorbis *f)
{
 if (IS_PUSH_MODE(f)) { error(f, VORBIS_invalid_api_mixing); return; }
 set_file_offset(f, f->first_audio_page_offset);
 f->previous_length = 0;
 f->first_decode = TRUE;
 f->next_seg = -1;
 vorbis_pump_first_frame(f);
}

unsigned int stb_vorbis_stream_length_in_samples(stb_vorbis *f)
{
 unsigned int restore_offset, previous_safe;
 unsigned int end, last_page_loc;

 if (IS_PUSH_MODE(f)) return error(f, VORBIS_invalid_api_mixing);
 if (!f->total_samples) {
 unsigned int last;
 uint32_t lo,hi;
 char header[6];

 /* first, store the current decode position so we can restore it */
 restore_offset = stb_vorbis_get_file_offset(f);

 /* now we want to seek back 64K from the end (the last page must
 * be at most a little less than 64K, but let's allow a little slop) */
 if (f->stream_len >= 65536 && f->stream_len-65536 >= f->first_audio_page_offset)
 previous_safe = f->stream_len - 65536;
 else
 previous_safe = f->first_audio_page_offset;

 set_file_offset(f, previous_safe);
 /* previous_safe is now our candidate 'earliest known place that seeking
 * to will lead to the final page' */

 if (!vorbis_find_page(f, &end, &last)) {
 /* if we can't find a page, we're hosed! */
 f->error = VORBIS_cant_find_last_page;
 f->total_samples = 0xffffffff;
 goto done;
 }

 /* check if there are more pages */
 last_page_loc = stb_vorbis_get_file_offset(f);

 /* stop when the last_page flag is set, not when we reach eof;
 * this allows us to stop short of a 'file_section' end without
 * explicitly checking the length of the section */
 while (!last) {
 set_file_offset(f, end);
 if (!vorbis_find_page(f, &end, &last)) {
 /* the last page we found didn't have the 'last page' flag
 * set. whoops! */
 break;
 }
 previous_safe = last_page_loc+1;
 last_page_loc = stb_vorbis_get_file_offset(f);
 }

 set_file_offset(f, last_page_loc);

 /* parse the header */
 getn(f, (unsigned char *)header, 6);
 /* extract the absolute granule position */
 lo = get32(f);
 hi = get32(f);
 if (lo == 0xffffffff && hi == 0xffffffff) {
 f->error = VORBIS_cant_find_last_page;
 f->total_samples = SAMPLE_unknown;
 goto done;
 }
 if (hi)
 lo = 0xfffffffe; /* saturate */
 f->total_samples = lo;

 f->p_last.page_start = last_page_loc;
 f->p_last.page_end = end;
 f->p_last.last_decoded_sample = lo;
 f->p_last.first_decoded_sample = SAMPLE_unknown;
 f->p_last.after_previous_page_start = previous_safe;

 done:
 set_file_offset(f, restore_offset);
 }
 return f->total_samples == SAMPLE_unknown ? 0 : f->total_samples;
}

float stb_vorbis_stream_length_in_seconds(stb_vorbis *f)
{
 return stb_vorbis_stream_length_in_samples(f) / (float) f->sample_rate;
}



int stb_vorbis_get_frame_float(stb_vorbis *f, int *channels, float ***output)
{
 int len, right,left,i;
 if (IS_PUSH_MODE(f)) return error(f, VORBIS_invalid_api_mixing);

 if (!vorbis_decode_packet(f, &len, &left, &right)) {
 f->channel_buffer_start = f->channel_buffer_end = 0;
 return 0;
 }

 len = vorbis_finish_frame(f, len, left, right);
 for (i=0; i < f->channels; ++i)
 f->outputs[i] = f->channel_buffers[i] + left;

 f->channel_buffer_start = left;
 f->channel_buffer_end = left+len;

 if (channels) *channels = f->channels;
 if (output) *output = f->outputs;
 return len;
}

stb_vorbis * stb_vorbis_open_memory(const unsigned char *data, int len, int *error, stb_vorbis_alloc *alloc)
{
 stb_vorbis *f, p;
 if (data == NULL) return NULL;
 vorbis_init(&p, alloc);
 p.stream = (uint8_t *) data;
 p.stream_end = (uint8_t *) data + len;
 p.stream_start = (uint8_t *) p.stream;
 p.stream_len = len;
 p.push_mode = FALSE;
 if (start_decoder(&p)) {
 f = vorbis_alloc(&p);
 if (f) {
 *f = p;
 vorbis_pump_first_frame(f);
 return f;
 }
 }
 if (error) *error = p.error;
 vorbis_deinit(&p);
 return NULL;
}

int stb_vorbis_get_samples_float_interleaved(stb_vorbis *f, int channels, float *buffer, int num_floats)
{
 float **outputs;
 int len = num_floats / channels;
 int n=0;
 int z = f->channels;
 if (z > channels) z = channels;
 while (n < len) {
 int i,j;
 int k = f->channel_buffer_end - f->channel_buffer_start;
 if (n+k >= len) k = len - n;
 for (j=0; j < k; ++j) {
 for (i=0; i < z; ++i)
 *buffer++ = f->channel_buffers[i][f->channel_buffer_start+j];
 for ( ; i < channels; ++i)
 *buffer++ = 0;
 }
 n += k;
 f->channel_buffer_start += k;
 if (n == len)
 break;
 if (!stb_vorbis_get_frame_float(f, NULL, &outputs))
 break;
 }
 return n;
}

int stb_vorbis_get_samples_float(stb_vorbis *f, int channels, float **buffer, int num_samples)
{
 float **outputs;
 int n=0;
 int z = f->channels;
 if (z > channels) z = channels;
 while (n < num_samples) {
 int i;
 int k = f->channel_buffer_end - f->channel_buffer_start;
 if (n+k >= num_samples) k = num_samples - n;
 if (k) {
 for (i=0; i < z; ++i)
 memcpy(buffer[i]+n, f->channel_buffers[i]+f->channel_buffer_start, sizeof(float)*k);
 for ( ; i < channels; ++i)
 memset(buffer[i]+n, 0, sizeof(float) * k);
 }
 n += k;
 f->channel_buffer_start += k;
 if (n == num_samples)
 break;
 if (!stb_vorbis_get_frame_float(f, NULL, &outputs))
 break;
 }
 return n;
}
#endif /* STB_VORBIS_NO_PULLDATA_API */

#endif /* STB_VORBIS_HEADER_ONLY */