ref: f0ac2d01765f938a4f3656efef440cf2c1bca69d
dir: /sys/src/cmd/audio/libFLAC/bitreader.c/
/* libFLAC - Free Lossless Audio Codec library
* Copyright (C) 2000-2009 Josh Coalson
* Copyright (C) 2011-2022 Xiph.Org Foundation
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of the Xiph.org Foundation nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdlib.h>
#include <string.h>
#include "private/bitmath.h"
#include "private/bitreader.h"
#include "private/crc.h"
#include "private/macros.h"
#include "FLAC/assert.h"
#include "share/compat.h"
#include "share/endswap.h"
/* Things should be fastest when this matches the machine word size */
/* WATCHOUT: if you change this you must also change the following #defines down to COUNT_ZERO_MSBS2 below to match */
/* WATCHOUT: there are a few places where the code will not work unless brword is >= 32 bits wide */
/* also, some sections currently only have fast versions for 4 or 8 bytes per word */
#if (ENABLE_64_BIT_WORDS == 0)
typedef FLAC__uint32 brword;
#define FLAC__BYTES_PER_WORD 4 /* sizeof brword */
#define FLAC__BITS_PER_WORD 32
#define FLAC__WORD_ALL_ONES ((FLAC__uint32)0xffffffff)
/* SWAP_BE_WORD_TO_HOST swaps bytes in a brword (which is always big-endian) if necessary to match host byte order */
#if WORDS_BIGENDIAN
#define SWAP_BE_WORD_TO_HOST(x) (x)
#else
#define SWAP_BE_WORD_TO_HOST(x) ENDSWAP_32(x)
#endif
/* counts the # of zero MSBs in a word */
#define COUNT_ZERO_MSBS(word) FLAC__clz_uint32(word)
#define COUNT_ZERO_MSBS2(word) FLAC__clz2_uint32(word)
#else
typedef FLAC__uint64 brword;
#define FLAC__BYTES_PER_WORD 8 /* sizeof brword */
#define FLAC__BITS_PER_WORD 64
#define FLAC__WORD_ALL_ONES ((FLAC__uint64)FLAC__U64L(0xffffffffffffffff))
/* SWAP_BE_WORD_TO_HOST swaps bytes in a brword (which is always big-endian) if necessary to match host byte order */
#if WORDS_BIGENDIAN
#define SWAP_BE_WORD_TO_HOST(x) (x)
#else
#define SWAP_BE_WORD_TO_HOST(x) ENDSWAP_64(x)
#endif
/* counts the # of zero MSBs in a word */
#define COUNT_ZERO_MSBS(word) FLAC__clz_uint64(word)
#define COUNT_ZERO_MSBS2(word) FLAC__clz2_uint64(word)
#endif
/*
* This should be at least twice as large as the largest number of words
* required to represent any 'number' (in any encoding) you are going to
* read. With FLAC this is on the order of maybe a few hundred bits.
* If the buffer is smaller than that, the decoder won't be able to read
* in a whole number that is in a variable length encoding (e.g. Rice).
* But to be practical it should be at least 1K bytes.
*
* Increase this number to decrease the number of read callbacks, at the
* expense of using more memory. Or decrease for the reverse effect,
* keeping in mind the limit from the first paragraph. The optimal size
* also depends on the CPU cache size and other factors; some twiddling
* may be necessary to squeeze out the best performance.
*/
static const uint32_t FLAC__BITREADER_DEFAULT_CAPACITY = 65536u / FLAC__BITS_PER_WORD; /* in words */
struct FLAC__BitReader {
/* any partially-consumed word at the head will stay right-justified as bits are consumed from the left */
/* any incomplete word at the tail will be left-justified, and bytes from the read callback are added on the right */
brword *buffer;
uint32_t capacity; /* in words */
uint32_t words; /* # of completed words in buffer */
uint32_t bytes; /* # of bytes in incomplete word at buffer[words] */
uint32_t consumed_words; /* #words ... */
uint32_t consumed_bits; /* ... + (#bits of head word) already consumed from the front of buffer */
uint32_t read_crc16; /* the running frame CRC */
uint32_t crc16_offset; /* the number of words in the current buffer that should not be CRC'd */
uint32_t crc16_align; /* the number of bits in the current consumed word that should not be CRC'd */
FLAC__bool read_limit_set; /* whether reads are limited */
uint32_t read_limit; /* the remaining size of what can be read */
uint32_t last_seen_framesync; /* the location of the last seen framesync, if it is in the buffer, in bits from front of buffer */
FLAC__BitReaderReadCallback read_callback;
void *client_data;
};
static inline void crc16_update_word_(FLAC__BitReader *br, brword word)
{
register uint32_t crc = br->read_crc16;
for ( ; br->crc16_align < FLAC__BITS_PER_WORD ; br->crc16_align += 8) {
uint32_t shift = FLAC__BITS_PER_WORD - 8 - br->crc16_align ;
crc = FLAC__CRC16_UPDATE ((uint32_t) (shift < FLAC__BITS_PER_WORD ? (word >> shift) & 0xff : 0), crc);
}
br->read_crc16 = crc;
br->crc16_align = 0;
}
static inline void crc16_update_block_(FLAC__BitReader *br)
{
if(br->consumed_words > br->crc16_offset && br->crc16_align)
crc16_update_word_(br, br->buffer[br->crc16_offset++]);
/* Prevent OOB read due to wrap-around. */
if (br->consumed_words > br->crc16_offset) {
#if FLAC__BYTES_PER_WORD == 4
br->read_crc16 = FLAC__crc16_update_words32(br->buffer + br->crc16_offset, br->consumed_words - br->crc16_offset, br->read_crc16);
#elif FLAC__BYTES_PER_WORD == 8
br->read_crc16 = FLAC__crc16_update_words64(br->buffer + br->crc16_offset, br->consumed_words - br->crc16_offset, br->read_crc16);
#else
unsigned i;
for (i = br->crc16_offset; i < br->consumed_words; i++)
crc16_update_word_(br, br->buffer[i]);
#endif
}
br->crc16_offset = 0;
}
static FLAC__bool bitreader_read_from_client_(FLAC__BitReader *br)
{
uint32_t start, end;
size_t bytes;
FLAC__byte *target;
#if WORDS_BIGENDIAN
#else
brword preswap_backup;
#endif
/* invalidate last seen framesync */
br->last_seen_framesync = -1;
/* first shift the unconsumed buffer data toward the front as much as possible */
if(br->consumed_words > 0) {
crc16_update_block_(br); /* CRC consumed words */
start = br->consumed_words;
end = br->words + (br->bytes? 1:0);
memmove(br->buffer, br->buffer+start, FLAC__BYTES_PER_WORD * (end - start));
br->words -= start;
br->consumed_words = 0;
}
/*
* set the target for reading, taking into account word alignment and endianness
*/
bytes = (br->capacity - br->words) * FLAC__BYTES_PER_WORD - br->bytes;
if(bytes == 0)
return false; /* no space left, buffer is too small; see note for FLAC__BITREADER_DEFAULT_CAPACITY */
target = ((FLAC__byte*)(br->buffer+br->words)) + br->bytes;
/* before reading, if the existing reader looks like this (say brword is 32 bits wide)
* bitstream : 11 22 33 44 55 br->words=1 br->bytes=1 (partial tail word is left-justified)
* buffer[BE]: 11 22 33 44 55 ?? ?? ?? (shown laid out as bytes sequentially in memory)
* buffer[LE]: 44 33 22 11 ?? ?? ?? 55 (?? being don't-care)
* ^^-------target, bytes=3
* on LE machines, have to byteswap the odd tail word so nothing is
* overwritten:
*/
#if WORDS_BIGENDIAN
#else
preswap_backup = br->buffer[br->words];
if(br->bytes)
br->buffer[br->words] = SWAP_BE_WORD_TO_HOST(br->buffer[br->words]);
#endif
/* now it looks like:
* bitstream : 11 22 33 44 55 br->words=1 br->bytes=1
* buffer[BE]: 11 22 33 44 55 ?? ?? ??
* buffer[LE]: 44 33 22 11 55 ?? ?? ??
* ^^-------target, bytes=3
*/
/* read in the data; note that the callback may return a smaller number of bytes */
if(!br->read_callback(target, &bytes, br->client_data)){
/* Despite the read callback failing, the data in the target
* might be used later, when the buffer is rewound. Therefore
* we revert the swap that was just done */
#if WORDS_BIGENDIAN
#else
br->buffer[br->words] = preswap_backup;
#endif
return false;
}
/* after reading bytes 66 77 88 99 AA BB CC DD EE FF from the client:
* bitstream : 11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF
* buffer[BE]: 11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF ??
* buffer[LE]: 44 33 22 11 55 66 77 88 99 AA BB CC DD EE FF ??
* now have to byteswap on LE machines:
*/
#if WORDS_BIGENDIAN
#else
end = (br->words*FLAC__BYTES_PER_WORD + br->bytes + (uint32_t)bytes + (FLAC__BYTES_PER_WORD-1)) / FLAC__BYTES_PER_WORD;
for(start = br->words; start < end; start++)
br->buffer[start] = SWAP_BE_WORD_TO_HOST(br->buffer[start]);
#endif
/* now it looks like:
* bitstream : 11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF
* buffer[BE]: 11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF ??
* buffer[LE]: 44 33 22 11 88 77 66 55 CC BB AA 99 ?? FF EE DD
* finally we'll update the reader values:
*/
end = br->words*FLAC__BYTES_PER_WORD + br->bytes + (uint32_t)bytes;
br->words = end / FLAC__BYTES_PER_WORD;
br->bytes = end % FLAC__BYTES_PER_WORD;
return true;
}
/***********************************************************************
*
* Class constructor/destructor
*
***********************************************************************/
FLAC__BitReader *FLAC__bitreader_new(void)
{
FLAC__BitReader *br = calloc(1, sizeof(FLAC__BitReader));
/* calloc() implies:
memset(br, 0, sizeof(FLAC__BitReader));
br->buffer = 0;
br->capacity = 0;
br->words = br->bytes = 0;
br->consumed_words = br->consumed_bits = 0;
br->read_callback = 0;
br->client_data = 0;
*/
return br;
}
void FLAC__bitreader_delete(FLAC__BitReader *br)
{
FLAC__ASSERT(0 != br);
FLAC__bitreader_free(br);
free(br);
}
/***********************************************************************
*
* Public class methods
*
***********************************************************************/
FLAC__bool FLAC__bitreader_init(FLAC__BitReader *br, FLAC__BitReaderReadCallback rcb, void *cd)
{
FLAC__ASSERT(0 != br);
br->words = br->bytes = 0;
br->consumed_words = br->consumed_bits = 0;
br->capacity = FLAC__BITREADER_DEFAULT_CAPACITY;
br->buffer = malloc(sizeof(brword) * br->capacity);
if(br->buffer == 0)
return false;
br->read_callback = rcb;
br->client_data = cd;
br->read_limit_set = false;
br->read_limit = -1;
br->last_seen_framesync = -1;
return true;
}
void FLAC__bitreader_free(FLAC__BitReader *br)
{
FLAC__ASSERT(0 != br);
if(0 != br->buffer)
free(br->buffer);
br->buffer = 0;
br->capacity = 0;
br->words = br->bytes = 0;
br->consumed_words = br->consumed_bits = 0;
br->read_callback = 0;
br->client_data = 0;
br->read_limit_set = false;
br->read_limit = -1;
br->last_seen_framesync = -1;
}
FLAC__bool FLAC__bitreader_clear(FLAC__BitReader *br)
{
br->words = br->bytes = 0;
br->consumed_words = br->consumed_bits = 0;
br->read_limit_set = false;
br->read_limit = -1;
br->last_seen_framesync = -1;
return true;
}
void FLAC__bitreader_set_framesync_location(FLAC__BitReader *br)
{
br->last_seen_framesync = br->consumed_words * FLAC__BYTES_PER_WORD + br->consumed_bits / 8;
}
FLAC__bool FLAC__bitreader_rewind_to_after_last_seen_framesync(FLAC__BitReader *br)
{
if(br->last_seen_framesync == (uint32_t)-1) {
br->consumed_words = br->consumed_bits = 0;
return false;
}
else {
br->consumed_words = (br->last_seen_framesync + 1) / FLAC__BYTES_PER_WORD;
br->consumed_bits = ((br->last_seen_framesync + 1) % FLAC__BYTES_PER_WORD) * 8;
return true;
}
}
void FLAC__bitreader_dump(const FLAC__BitReader *br, FILE *out)
{
uint32_t i, j;
if(br == 0) {
fprintf(out, "bitreader is NULL\n");
}
else {
fprintf(out, "bitreader: capacity=%u words=%u bytes=%u consumed: words=%u, bits=%u\n", br->capacity, br->words, br->bytes, br->consumed_words, br->consumed_bits);
for(i = 0; i < br->words; i++) {
fprintf(out, "%08X: ", i);
for(j = 0; j < FLAC__BITS_PER_WORD; j++)
if(i < br->consumed_words || (i == br->consumed_words && j < br->consumed_bits))
fprintf(out, ".");
else
fprintf(out, "%01d", br->buffer[i] & ((brword)1 << (FLAC__BITS_PER_WORD-j-1)) ? 1:0);
fprintf(out, "\n");
}
if(br->bytes > 0) {
fprintf(out, "%08X: ", i);
for(j = 0; j < br->bytes*8; j++)
if(i < br->consumed_words || (i == br->consumed_words && j < br->consumed_bits))
fprintf(out, ".");
else
fprintf(out, "%01d", br->buffer[i] & ((brword)1 << (br->bytes*8-j-1)) ? 1:0);
fprintf(out, "\n");
}
}
}
void FLAC__bitreader_reset_read_crc16(FLAC__BitReader *br, FLAC__uint16 seed)
{
FLAC__ASSERT(0 != br);
FLAC__ASSERT(0 != br->buffer);
FLAC__ASSERT((br->consumed_bits & 7) == 0);
br->read_crc16 = (uint32_t)seed;
br->crc16_offset = br->consumed_words;
br->crc16_align = br->consumed_bits;
}
FLAC__uint16 FLAC__bitreader_get_read_crc16(FLAC__BitReader *br)
{
FLAC__ASSERT(0 != br);
FLAC__ASSERT(0 != br->buffer);
/* CRC consumed words up to here */
crc16_update_block_(br);
FLAC__ASSERT((br->consumed_bits & 7) == 0);
FLAC__ASSERT(br->crc16_align <= br->consumed_bits);
/* CRC any tail bytes in a partially-consumed word */
if(br->consumed_bits) {
const brword tail = br->buffer[br->consumed_words];
for( ; br->crc16_align < br->consumed_bits; br->crc16_align += 8)
br->read_crc16 = FLAC__CRC16_UPDATE((uint32_t)((tail >> (FLAC__BITS_PER_WORD-8-br->crc16_align)) & 0xff), br->read_crc16);
}
return br->read_crc16;
}
inline FLAC__bool FLAC__bitreader_is_consumed_byte_aligned(const FLAC__BitReader *br)
{
return ((br->consumed_bits & 7) == 0);
}
inline uint32_t FLAC__bitreader_bits_left_for_byte_alignment(const FLAC__BitReader *br)
{
return 8 - (br->consumed_bits & 7);
}
inline uint32_t FLAC__bitreader_get_input_bits_unconsumed(const FLAC__BitReader *br)
{
return (br->words-br->consumed_words)*FLAC__BITS_PER_WORD + br->bytes*8 - br->consumed_bits;
}
void FLAC__bitreader_set_limit(FLAC__BitReader *br, uint32_t limit)
{
br->read_limit = limit;
br->read_limit_set = true;
}
void FLAC__bitreader_remove_limit(FLAC__BitReader *br)
{
br->read_limit_set = false;
br->read_limit = -1;
}
uint32_t FLAC__bitreader_limit_remaining(FLAC__BitReader *br)
{
FLAC__ASSERT(br->read_limit_set);
return br->read_limit;
}
void FLAC__bitreader_limit_invalidate(FLAC__BitReader *br)
{
br->read_limit = -1;
}
FLAC__bool FLAC__bitreader_read_raw_uint32(FLAC__BitReader *br, FLAC__uint32 *val, uint32_t bits)
{
FLAC__ASSERT(0 != br);
FLAC__ASSERT(0 != br->buffer);
FLAC__ASSERT(bits <= 32);
FLAC__ASSERT((br->capacity*FLAC__BITS_PER_WORD) * 2 >= bits);
FLAC__ASSERT(br->consumed_words <= br->words);
/* WATCHOUT: code does not work with <32bit words; we can make things much faster with this assertion */
FLAC__ASSERT(FLAC__BITS_PER_WORD >= 32);
if(bits == 0) { /* OPT: investigate if this can ever happen, maybe change to assertion */
*val = 0;
return true;
}
if(br->read_limit_set && br->read_limit < (uint32_t)-1){
if(br->read_limit < bits) {
br->read_limit = -1;
return false;
}
else
br->read_limit -= bits;
}
while((br->words-br->consumed_words)*FLAC__BITS_PER_WORD + br->bytes*8 - br->consumed_bits < bits) {
if(!bitreader_read_from_client_(br))
return false;
}
if(br->consumed_words < br->words) { /* if we've not consumed up to a partial tail word... */
/* OPT: taking out the consumed_bits==0 "else" case below might make things faster if less code allows the compiler to inline this function */
if(br->consumed_bits) {
/* this also works when consumed_bits==0, it's just a little slower than necessary for that case */
const uint32_t n = FLAC__BITS_PER_WORD - br->consumed_bits;
const brword word = br->buffer[br->consumed_words];
const brword mask = br->consumed_bits < FLAC__BITS_PER_WORD ? FLAC__WORD_ALL_ONES >> br->consumed_bits : 0;
if(bits < n) {
uint32_t shift = n - bits;
*val = shift < FLAC__BITS_PER_WORD ? (FLAC__uint32)((word & mask) >> shift) : 0; /* The result has <= 32 non-zero bits */
br->consumed_bits += bits;
return true;
}
/* (FLAC__BITS_PER_WORD - br->consumed_bits <= bits) ==> (FLAC__WORD_ALL_ONES >> br->consumed_bits) has no more than 'bits' non-zero bits */
*val = (FLAC__uint32)(word & mask);
bits -= n;
br->consumed_words++;
br->consumed_bits = 0;
if(bits) { /* if there are still bits left to read, there have to be less than 32 so they will all be in the next word */
uint32_t shift = FLAC__BITS_PER_WORD - bits;
*val = bits < 32 ? *val << bits : 0;
*val |= shift < FLAC__BITS_PER_WORD ? (FLAC__uint32)(br->buffer[br->consumed_words] >> shift) : 0;
br->consumed_bits = bits;
}
return true;
}
else { /* br->consumed_bits == 0 */
const brword word = br->buffer[br->consumed_words];
if(bits < FLAC__BITS_PER_WORD) {
*val = (FLAC__uint32)(word >> (FLAC__BITS_PER_WORD-bits));
br->consumed_bits = bits;
return true;
}
/* at this point bits == FLAC__BITS_PER_WORD == 32; because of previous assertions, it can't be larger */
*val = (FLAC__uint32)word;
br->consumed_words++;
return true;
}
}
else {
/* in this case we're starting our read at a partial tail word;
* the reader has guaranteed that we have at least 'bits' bits
* available to read, which makes this case simpler.
*/
/* OPT: taking out the consumed_bits==0 "else" case below might make things faster if less code allows the compiler to inline this function */
if(br->consumed_bits) {
/* this also works when consumed_bits==0, it's just a little slower than necessary for that case */
FLAC__ASSERT(br->consumed_bits + bits <= br->bytes*8);
*val = (FLAC__uint32)((br->buffer[br->consumed_words] & (FLAC__WORD_ALL_ONES >> br->consumed_bits)) >> (FLAC__BITS_PER_WORD-br->consumed_bits-bits));
br->consumed_bits += bits;
return true;
}
else {
*val = (FLAC__uint32)(br->buffer[br->consumed_words] >> (FLAC__BITS_PER_WORD-bits));
br->consumed_bits += bits;
return true;
}
}
}
FLAC__bool FLAC__bitreader_read_raw_int32(FLAC__BitReader *br, FLAC__int32 *val, uint32_t bits)
{
FLAC__uint32 uval, mask;
/* OPT: inline raw uint32 code here, or make into a macro if possible in the .h file */
if (bits < 1 || ! FLAC__bitreader_read_raw_uint32(br, &uval, bits))
return false;
/* sign-extend *val assuming it is currently bits wide. */
/* From: https://graphics.stanford.edu/~seander/bithacks.html#FixedSignExtend */
mask = bits >= 33 ? 0 : 1lu << (bits - 1);
*val = (uval ^ mask) - mask;
return true;
}
FLAC__bool FLAC__bitreader_read_raw_uint64(FLAC__BitReader *br, FLAC__uint64 *val, uint32_t bits)
{
FLAC__uint32 hi, lo;
if(bits > 32) {
if(!FLAC__bitreader_read_raw_uint32(br, &hi, bits-32))
return false;
if(!FLAC__bitreader_read_raw_uint32(br, &lo, 32))
return false;
*val = hi;
*val <<= 32;
*val |= lo;
}
else {
if(!FLAC__bitreader_read_raw_uint32(br, &lo, bits))
return false;
*val = lo;
}
return true;
}
FLAC__bool FLAC__bitreader_read_raw_int64(FLAC__BitReader *br, FLAC__int64 *val, uint32_t bits)
{
FLAC__uint64 uval, mask;
/* OPT: inline raw uint64 code here, or make into a macro if possible in the .h file */
if (bits < 1 || ! FLAC__bitreader_read_raw_uint64(br, &uval, bits))
return false;
/* sign-extend *val assuming it is currently bits wide. */
/* From: https://graphics.stanford.edu/~seander/bithacks.html#FixedSignExtend */
mask = bits >= 65 ? 0 : 1llu << (bits - 1);
*val = (uval ^ mask) - mask;
return true;
}
inline FLAC__bool FLAC__bitreader_read_uint32_little_endian(FLAC__BitReader *br, FLAC__uint32 *val)
{
FLAC__uint32 x8, x32 = 0;
/* this doesn't need to be that fast as currently it is only used for vorbis comments */
if(!FLAC__bitreader_read_raw_uint32(br, &x32, 8))
return false;
if(!FLAC__bitreader_read_raw_uint32(br, &x8, 8))
return false;
x32 |= (x8 << 8);
if(!FLAC__bitreader_read_raw_uint32(br, &x8, 8))
return false;
x32 |= (x8 << 16);
if(!FLAC__bitreader_read_raw_uint32(br, &x8, 8))
return false;
x32 |= (x8 << 24);
*val = x32;
return true;
}
FLAC__bool FLAC__bitreader_skip_bits_no_crc(FLAC__BitReader *br, uint32_t bits)
{
/*
* OPT: a faster implementation is possible but probably not that useful
* since this is only called a couple of times in the metadata readers.
*/
FLAC__ASSERT(0 != br);
FLAC__ASSERT(0 != br->buffer);
if(bits > 0) {
const uint32_t n = br->consumed_bits & 7;
uint32_t m;
FLAC__uint32 x;
if(n != 0) {
m = flac_min(8-n, bits);
if(!FLAC__bitreader_read_raw_uint32(br, &x, m))
return false;
bits -= m;
}
m = bits / 8;
if(m > 0) {
if(!FLAC__bitreader_skip_byte_block_aligned_no_crc(br, m))
return false;
bits %= 8;
}
if(bits > 0) {
if(!FLAC__bitreader_read_raw_uint32(br, &x, bits))
return false;
}
}
return true;
}
FLAC__bool FLAC__bitreader_skip_byte_block_aligned_no_crc(FLAC__BitReader *br, uint32_t nvals)
{
FLAC__uint32 x;
FLAC__ASSERT(0 != br);
FLAC__ASSERT(0 != br->buffer);
FLAC__ASSERT(FLAC__bitreader_is_consumed_byte_aligned(br));
if(br->read_limit_set && br->read_limit < (uint32_t)-1){
if(br->read_limit < nvals*8){
br->read_limit = -1;
return false;
}
}
/* step 1: skip over partial head word to get word aligned */
while(nvals && br->consumed_bits) { /* i.e. run until we read 'nvals' bytes or we hit the end of the head word */
if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
return false;
nvals--;
}
if(0 == nvals)
return true;
/* step 2: skip whole words in chunks */
while(nvals >= FLAC__BYTES_PER_WORD) {
if(br->consumed_words < br->words) {
br->consumed_words++;
nvals -= FLAC__BYTES_PER_WORD;
if(br->read_limit_set)
br->read_limit -= FLAC__BITS_PER_WORD;
}
else if(!bitreader_read_from_client_(br))
return false;
}
/* step 3: skip any remainder from partial tail bytes */
while(nvals) {
if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
return false;
nvals--;
}
return true;
}
FLAC__bool FLAC__bitreader_read_byte_block_aligned_no_crc(FLAC__BitReader *br, FLAC__byte *val, uint32_t nvals)
{
FLAC__uint32 x;
FLAC__ASSERT(0 != br);
FLAC__ASSERT(0 != br->buffer);
FLAC__ASSERT(FLAC__bitreader_is_consumed_byte_aligned(br));
if(br->read_limit_set && br->read_limit < (uint32_t)-1){
if(br->read_limit < nvals*8){
br->read_limit = -1;
return false;
}
}
/* step 1: read from partial head word to get word aligned */
while(nvals && br->consumed_bits) { /* i.e. run until we read 'nvals' bytes or we hit the end of the head word */
if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
return false;
*val++ = (FLAC__byte)x;
nvals--;
}
if(0 == nvals)
return true;
/* step 2: read whole words in chunks */
while(nvals >= FLAC__BYTES_PER_WORD) {
if(br->consumed_words < br->words) {
const brword word = br->buffer[br->consumed_words++];
#if FLAC__BYTES_PER_WORD == 4
val[0] = (FLAC__byte)(word >> 24);
val[1] = (FLAC__byte)(word >> 16);
val[2] = (FLAC__byte)(word >> 8);
val[3] = (FLAC__byte)word;
#elif FLAC__BYTES_PER_WORD == 8
val[0] = (FLAC__byte)(word >> 56);
val[1] = (FLAC__byte)(word >> 48);
val[2] = (FLAC__byte)(word >> 40);
val[3] = (FLAC__byte)(word >> 32);
val[4] = (FLAC__byte)(word >> 24);
val[5] = (FLAC__byte)(word >> 16);
val[6] = (FLAC__byte)(word >> 8);
val[7] = (FLAC__byte)word;
#else
for(x = 0; x < FLAC__BYTES_PER_WORD; x++)
val[x] = (FLAC__byte)(word >> (8*(FLAC__BYTES_PER_WORD-x-1)));
#endif
val += FLAC__BYTES_PER_WORD;
nvals -= FLAC__BYTES_PER_WORD;
if(br->read_limit_set)
br->read_limit -= FLAC__BITS_PER_WORD;
}
else if(!bitreader_read_from_client_(br))
return false;
}
/* step 3: read any remainder from partial tail bytes */
while(nvals) {
if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
return false;
*val++ = (FLAC__byte)x;
nvals--;
}
return true;
}
FLAC__bool FLAC__bitreader_read_unary_unsigned(FLAC__BitReader *br, uint32_t *val)
#if 0 /* slow but readable version */
{
uint32_t bit;
FLAC__ASSERT(0 != br);
FLAC__ASSERT(0 != br->buffer);
*val = 0;
while(1) {
if(!FLAC__bitreader_read_bit(br, &bit))
return false;
if(bit)
break;
else
*val++;
}
return true;
}
#else
{
uint32_t i;
FLAC__ASSERT(0 != br);
FLAC__ASSERT(0 != br->buffer);
*val = 0;
while(1) {
while(br->consumed_words < br->words) { /* if we've not consumed up to a partial tail word... */
brword b = br->consumed_bits < FLAC__BITS_PER_WORD ? br->buffer[br->consumed_words] << br->consumed_bits : 0;
if(b) {
i = COUNT_ZERO_MSBS(b);
*val += i;
i++;
br->consumed_bits += i;
if(br->consumed_bits >= FLAC__BITS_PER_WORD) { /* faster way of testing if(br->consumed_bits == FLAC__BITS_PER_WORD) */
br->consumed_words++;
br->consumed_bits = 0;
}
return true;
}
else {
*val += FLAC__BITS_PER_WORD - br->consumed_bits;
br->consumed_words++;
br->consumed_bits = 0;
/* didn't find stop bit yet, have to keep going... */
}
}
/* at this point we've eaten up all the whole words; have to try
* reading through any tail bytes before calling the read callback.
* this is a repeat of the above logic adjusted for the fact we
* don't have a whole word. note though if the client is feeding
* us data a byte at a time (unlikely), br->consumed_bits may not
* be zero.
*/
if(br->bytes*8 > br->consumed_bits) {
const uint32_t end = br->bytes * 8;
brword b = (br->buffer[br->consumed_words] & (FLAC__WORD_ALL_ONES << (FLAC__BITS_PER_WORD-end))) << br->consumed_bits;
if(b) {
i = COUNT_ZERO_MSBS(b);
*val += i;
i++;
br->consumed_bits += i;
FLAC__ASSERT(br->consumed_bits < FLAC__BITS_PER_WORD);
return true;
}
else {
*val += end - br->consumed_bits;
br->consumed_bits = end;
FLAC__ASSERT(br->consumed_bits < FLAC__BITS_PER_WORD);
/* didn't find stop bit yet, have to keep going... */
}
}
if(!bitreader_read_from_client_(br))
return false;
}
}
#endif
#if 0 /* unused */
FLAC__bool FLAC__bitreader_read_rice_signed(FLAC__BitReader *br, int *val, uint32_t parameter)
{
FLAC__uint32 lsbs = 0, msbs = 0;
uint32_t uval;
FLAC__ASSERT(0 != br);
FLAC__ASSERT(0 != br->buffer);
FLAC__ASSERT(parameter <= 31);
/* read the unary MSBs and end bit */
if(!FLAC__bitreader_read_unary_unsigned(br, &msbs))
return false;
/* read the binary LSBs */
if(!FLAC__bitreader_read_raw_uint32(br, &lsbs, parameter))
return false;
/* compose the value */
uval = (msbs << parameter) | lsbs;
if(uval & 1)
*val = -((int)(uval >> 1)) - 1;
else
*val = (int)(uval >> 1);
return true;
}
#endif
/* this is by far the most heavily used reader call. it ain't pretty but it's fast */
FLAC__bool FLAC__bitreader_read_rice_signed_block(FLAC__BitReader *br, int vals[], uint32_t nvals, uint32_t parameter)
{
/* try and get br->consumed_words and br->consumed_bits into register;
* must remember to flush them back to *br before calling other
* bitreader functions that use them, and before returning */
uint32_t cwords, words, lsbs, msbs, x, y, limit;
uint32_t ucbits; /* keep track of the number of unconsumed bits in word */
brword b;
int *val, *end;
FLAC__ASSERT(0 != br);
FLAC__ASSERT(0 != br->buffer);
/* WATCHOUT: code does not work with <32bit words; we can make things much faster with this assertion */
FLAC__ASSERT(FLAC__BITS_PER_WORD >= 32);
FLAC__ASSERT(parameter < 32);
/* the above two asserts also guarantee that the binary part never straddles more than 2 words, so we don't have to loop to read it */
limit = UINT32_MAX >> parameter; /* Maximal msbs that can occur with residual bounded to int32_t */
val = vals;
end = vals + nvals;
if(parameter == 0) {
while(val < end) {
/* read the unary MSBs and end bit */
if(!FLAC__bitreader_read_unary_unsigned(br, &msbs))
return false;
/* Checking limit here would be overzealous: coding UINT32_MAX
* with parameter == 0 would take 4GiB */
*val++ = (int)(msbs >> 1) ^ -(int)(msbs & 1);
}
return true;
}
FLAC__ASSERT(parameter > 0);
cwords = br->consumed_words;
words = br->words;
/* if we've not consumed up to a partial tail word... */
if(cwords >= words) {
x = 0;
goto process_tail;
}
ucbits = FLAC__BITS_PER_WORD - br->consumed_bits;
b = br->buffer[cwords] << br->consumed_bits; /* keep unconsumed bits aligned to left */
while(val < end) {
/* read the unary MSBs and end bit */
x = y = COUNT_ZERO_MSBS2(b);
if(x == FLAC__BITS_PER_WORD) {
x = ucbits;
do {
/* didn't find stop bit yet, have to keep going... */
cwords++;
if (cwords >= words)
goto incomplete_msbs;
b = br->buffer[cwords];
y = COUNT_ZERO_MSBS2(b);
x += y;
} while(y == FLAC__BITS_PER_WORD);
}
b <<= y;
b <<= 1; /* account for stop bit */
ucbits = (ucbits - x - 1) % FLAC__BITS_PER_WORD;
msbs = x;
if(x > limit)
return false;
/* read the binary LSBs */
x = (FLAC__uint32)(b >> (FLAC__BITS_PER_WORD - parameter)); /* parameter < 32, so we can cast to 32-bit uint32_t */
if(parameter <= ucbits) {
ucbits -= parameter;
b <<= parameter;
} else {
/* there are still bits left to read, they will all be in the next word */
cwords++;
if (cwords >= words)
goto incomplete_lsbs;
b = br->buffer[cwords];
ucbits += FLAC__BITS_PER_WORD - parameter;
x |= (FLAC__uint32)(b >> ucbits);
b <<= FLAC__BITS_PER_WORD - ucbits;
}
lsbs = x;
/* compose the value */
x = (msbs << parameter) | lsbs;
*val++ = (int)(x >> 1) ^ -(int)(x & 1);
continue;
/* at this point we've eaten up all the whole words */
process_tail:
do {
if(0) {
incomplete_msbs:
br->consumed_bits = 0;
br->consumed_words = cwords;
}
/* read the unary MSBs and end bit */
if(!FLAC__bitreader_read_unary_unsigned(br, &msbs))
return false;
msbs += x;
x = ucbits = 0;
if(0) {
incomplete_lsbs:
br->consumed_bits = 0;
br->consumed_words = cwords;
}
/* read the binary LSBs */
if(!FLAC__bitreader_read_raw_uint32(br, &lsbs, parameter - ucbits))
return false;
lsbs = x | lsbs;
/* compose the value */
x = (msbs << parameter) | lsbs;
*val++ = (int)(x >> 1) ^ -(int)(x & 1);
x = 0;
cwords = br->consumed_words;
words = br->words;
ucbits = FLAC__BITS_PER_WORD - br->consumed_bits;
b = cwords < br->capacity ? br->buffer[cwords] << br->consumed_bits : 0;
} while(cwords >= words && val < end);
}
if(ucbits == 0 && cwords < words) {
/* don't leave the head word with no unconsumed bits */
cwords++;
ucbits = FLAC__BITS_PER_WORD;
}
br->consumed_bits = FLAC__BITS_PER_WORD - ucbits;
br->consumed_words = cwords;
return true;
}
#if 0 /* UNUSED */
FLAC__bool FLAC__bitreader_read_golomb_signed(FLAC__BitReader *br, int *val, uint32_t parameter)
{
FLAC__uint32 lsbs = 0, msbs = 0;
uint32_t bit, uval, k;
FLAC__ASSERT(0 != br);
FLAC__ASSERT(0 != br->buffer);
k = FLAC__bitmath_ilog2(parameter);
/* read the unary MSBs and end bit */
if(!FLAC__bitreader_read_unary_unsigned(br, &msbs))
return false;
/* read the binary LSBs */
if(!FLAC__bitreader_read_raw_uint32(br, &lsbs, k))
return false;
if(parameter == 1u<<k) {
/* compose the value */
uval = (msbs << k) | lsbs;
}
else {
uint32_t d = (1 << (k+1)) - parameter;
if(lsbs >= d) {
if(!FLAC__bitreader_read_bit(br, &bit))
return false;
lsbs <<= 1;
lsbs |= bit;
lsbs -= d;
}
/* compose the value */
uval = msbs * parameter + lsbs;
}
/* unfold uint32_t to signed */
if(uval & 1)
*val = -((int)(uval >> 1)) - 1;
else
*val = (int)(uval >> 1);
return true;
}
FLAC__bool FLAC__bitreader_read_golomb_unsigned(FLAC__BitReader *br, uint32_t *val, uint32_t parameter)
{
FLAC__uint32 lsbs, msbs = 0;
uint32_t bit, k;
FLAC__ASSERT(0 != br);
FLAC__ASSERT(0 != br->buffer);
k = FLAC__bitmath_ilog2(parameter);
/* read the unary MSBs and end bit */
if(!FLAC__bitreader_read_unary_unsigned(br, &msbs))
return false;
/* read the binary LSBs */
if(!FLAC__bitreader_read_raw_uint32(br, &lsbs, k))
return false;
if(parameter == 1u<<k) {
/* compose the value */
*val = (msbs << k) | lsbs;
}
else {
uint32_t d = (1 << (k+1)) - parameter;
if(lsbs >= d) {
if(!FLAC__bitreader_read_bit(br, &bit))
return false;
lsbs <<= 1;
lsbs |= bit;
lsbs -= d;
}
/* compose the value */
*val = msbs * parameter + lsbs;
}
return true;
}
#endif /* UNUSED */
/* on return, if *val == 0xffffffff then the utf-8 sequence was invalid, but the return value will be true */
FLAC__bool FLAC__bitreader_read_utf8_uint32(FLAC__BitReader *br, FLAC__uint32 *val, FLAC__byte *raw, uint32_t *rawlen)
{
FLAC__uint32 v = 0;
FLAC__uint32 x;
uint32_t i;
if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
return false;
if(raw)
raw[(*rawlen)++] = (FLAC__byte)x;
if(!(x & 0x80)) { /* 0xxxxxxx */
v = x;
i = 0;
}
else if(x & 0xC0 && !(x & 0x20)) { /* 110xxxxx */
v = x & 0x1F;
i = 1;
}
else if(x & 0xE0 && !(x & 0x10)) { /* 1110xxxx */
v = x & 0x0F;
i = 2;
}
else if(x & 0xF0 && !(x & 0x08)) { /* 11110xxx */
v = x & 0x07;
i = 3;
}
else if(x & 0xF8 && !(x & 0x04)) { /* 111110xx */
v = x & 0x03;
i = 4;
}
else if(x & 0xFC && !(x & 0x02)) { /* 1111110x */
v = x & 0x01;
i = 5;
}
else {
*val = 0xffffffff;
return true;
}
for( ; i; i--) {
if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
return false;
if(raw)
raw[(*rawlen)++] = (FLAC__byte)x;
if(!(x & 0x80) || (x & 0x40)) { /* 10xxxxxx */
*val = 0xffffffff;
return true;
}
v <<= 6;
v |= (x & 0x3F);
}
*val = v;
return true;
}
/* on return, if *val == 0xffffffffffffffff then the utf-8 sequence was invalid, but the return value will be true */
FLAC__bool FLAC__bitreader_read_utf8_uint64(FLAC__BitReader *br, FLAC__uint64 *val, FLAC__byte *raw, uint32_t *rawlen)
{
FLAC__uint64 v = 0;
FLAC__uint32 x;
uint32_t i;
if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
return false;
if(raw)
raw[(*rawlen)++] = (FLAC__byte)x;
if(!(x & 0x80)) { /* 0xxxxxxx */
v = x;
i = 0;
}
else if(x & 0xC0 && !(x & 0x20)) { /* 110xxxxx */
v = x & 0x1F;
i = 1;
}
else if(x & 0xE0 && !(x & 0x10)) { /* 1110xxxx */
v = x & 0x0F;
i = 2;
}
else if(x & 0xF0 && !(x & 0x08)) { /* 11110xxx */
v = x & 0x07;
i = 3;
}
else if(x & 0xF8 && !(x & 0x04)) { /* 111110xx */
v = x & 0x03;
i = 4;
}
else if(x & 0xFC && !(x & 0x02)) { /* 1111110x */
v = x & 0x01;
i = 5;
}
else if(x & 0xFE && !(x & 0x01)) { /* 11111110 */
v = 0;
i = 6;
}
else {
*val = FLAC__U64L(0xffffffffffffffff);
return true;
}
for( ; i; i--) {
if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
return false;
if(raw)
raw[(*rawlen)++] = (FLAC__byte)x;
if(!(x & 0x80) || (x & 0x40)) { /* 10xxxxxx */
*val = FLAC__U64L(0xffffffffffffffff);
return true;
}
v <<= 6;
v |= (x & 0x3F);
}
*val = v;
return true;
}
/* These functions are declared inline in this file but are also callable as
* externs from elsewhere.
* According to the C99 spec, section 6.7.4, simply providing a function
* prototype in a header file without 'inline' and making the function inline
* in this file should be sufficient.
* Unfortunately, the Microsoft VS compiler doesn't pick them up externally. To
* fix that we add extern declarations here.
*/
extern FLAC__bool FLAC__bitreader_is_consumed_byte_aligned(const FLAC__BitReader *br);
extern uint32_t FLAC__bitreader_bits_left_for_byte_alignment(const FLAC__BitReader *br);
extern uint32_t FLAC__bitreader_get_input_bits_unconsumed(const FLAC__BitReader *br);
extern FLAC__bool FLAC__bitreader_read_uint32_little_endian(FLAC__BitReader *br, FLAC__uint32 *val);