mirror of
https://github.com/Rockbox/rockbox.git
synced 2026-10-10 08:03:04 -04:00
330236911b
The folded Rice value was unfolded with a signed shift, which is wrong once it reaches 2^31, and the unary length limit was (INT_MAX >> k) + 2, about half of what a 32-bit residual can need. Streams with very large residuals (FLAC decoder testbench file 63) were misparsed, overran the frame and lost sync at the next one. Unfold as unsigned and derive the limit from UINT_MAX, clamped to INT_MAX. The fast path is unchanged. The existing 0x80000000 error check now also works as intended, since the Golomb reader's error value maps to it. The FLAC spec forbids a residual of -2^31. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Change-Id: I0bdce9db69e1b30565ecc23126923ba401b7deca
128 lines
3.7 KiB
C
128 lines
3.7 KiB
C
/*
|
|
* exp golomb vlc stuff
|
|
* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
|
|
* Copyright (c) 2004 Alex Beregszaszi
|
|
*
|
|
* This library is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Lesser General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2 of the License, or (at your option) any later version.
|
|
*
|
|
* This library is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with this library; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
*
|
|
*/
|
|
|
|
#include <limits.h>
|
|
#include "codeclib.h"
|
|
|
|
/**
|
|
* @file golomb.h
|
|
* @brief
|
|
* exp golomb vlc stuff
|
|
* @author Michael Niedermayer <michaelni@gmx.at> and Alex Beregszaszi
|
|
*/
|
|
|
|
|
|
/**
|
|
* read unsigned golomb rice code (jpegls).
|
|
*/
|
|
static inline int get_ur_golomb_jpegls(GetBitContext *gb, int k, int limit,
|
|
int esc_len)
|
|
{
|
|
unsigned int buf;
|
|
int log;
|
|
|
|
OPEN_READER(re, gb);
|
|
UPDATE_CACHE(re, gb);
|
|
buf = GET_CACHE(re, gb);
|
|
|
|
log = av_log2(buf);
|
|
|
|
if (log - k >= 32 - MIN_CACHE_BITS + (MIN_CACHE_BITS == 32) &&
|
|
32 - log < limit) {
|
|
buf >>= log - k;
|
|
buf += (30U - log) << k;
|
|
LAST_SKIP_BITS(re, gb, 32 + k - log);
|
|
CLOSE_READER(re, gb);
|
|
|
|
return buf;
|
|
} else {
|
|
int i;
|
|
for (i = 0; i + MIN_CACHE_BITS <= limit && SHOW_UBITS(re, gb, MIN_CACHE_BITS) == 0; i += MIN_CACHE_BITS) {
|
|
if (gb->size_in_bits <= (signed) re_index) {
|
|
CLOSE_READER(re, gb);
|
|
return -1;
|
|
}
|
|
LAST_SKIP_BITS(re, gb, MIN_CACHE_BITS);
|
|
UPDATE_CACHE(re, gb);
|
|
}
|
|
for (; i < limit && SHOW_UBITS(re, gb, 1) == 0; i++) {
|
|
SKIP_BITS(re, gb, 1);
|
|
}
|
|
LAST_SKIP_BITS(re, gb, 1);
|
|
UPDATE_CACHE(re, gb);
|
|
|
|
if (i < limit - 1) {
|
|
if (k) {
|
|
if (k > MIN_CACHE_BITS - 1) {
|
|
buf = SHOW_UBITS(re, gb, 16) << (k-16);
|
|
LAST_SKIP_BITS(re, gb, 16);
|
|
UPDATE_CACHE(re, gb);
|
|
buf |= SHOW_UBITS(re, gb, k-16);
|
|
LAST_SKIP_BITS(re, gb, k-16);
|
|
} else {
|
|
buf = SHOW_UBITS(re, gb, k);
|
|
LAST_SKIP_BITS(re, gb, k);
|
|
}
|
|
} else {
|
|
buf = 0;
|
|
}
|
|
|
|
buf += ((unsigned int)i << k);
|
|
} else if (i == limit - 1) {
|
|
buf = SHOW_UBITS(re, gb, esc_len);
|
|
LAST_SKIP_BITS(re, gb, esc_len);
|
|
|
|
buf ++;
|
|
} else {
|
|
buf = -1;
|
|
}
|
|
CLOSE_READER(re, gb);
|
|
return buf;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* read signed golomb rice code (flac).
|
|
*/
|
|
static inline int get_sr_golomb_flac(GetBitContext *gb, int k, int limit, int esc_len){
|
|
/* The folded value can use all 32 bits, so unfold it as unsigned. */
|
|
unsigned int v= get_ur_golomb_jpegls(gb, k, limit, esc_len);
|
|
return (int)((v>>1) ^ -(v&1));
|
|
}
|
|
|
|
/**
|
|
* read unsigned golomb rice code (shorten).
|
|
*/
|
|
#define get_ur_golomb_shorten(gb, k) get_ur_golomb_jpegls(gb, k, INT_MAX, 0)
|
|
/*
|
|
static inline unsigned int get_ur_golomb_shorten(GetBitContext *gb, int k){
|
|
return get_ur_golomb_jpegls(gb, k, INT_MAX, 0);
|
|
}
|
|
*/
|
|
|
|
/**
|
|
* read signed golomb rice code (shorten).
|
|
*/
|
|
static inline int get_sr_golomb_shorten(GetBitContext* gb, int k)
|
|
{
|
|
int uvar = get_ur_golomb_jpegls(gb, k + 1, INT_MAX, 0);
|
|
return (uvar >> 1) ^ -(uvar & 1);
|
|
}
|