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FFmpeg/libavcodec/golomb.h
Luca Barbato 19c5fa9eea golomb: Simplify get_ur_golomb_jpegls 
The loop always consumes the bit read and the new bitstream reader
can read 0 bits just fine.
2017-04-13 13:37:10 +02:00

526 lines
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/*
* exp golomb vlc stuff
* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
* Copyright (c) 2004 Alex Beregszaszi
*
* This file is part of Libav.
*
* Libav 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 2.1 of the License, or (at your option) any later version.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* @brief
* exp golomb vlc stuff
* @author Michael Niedermayer <michaelni@gmx.at> and Alex Beregszaszi
*/
#ifndef AVCODEC_GOLOMB_H
#define AVCODEC_GOLOMB_H
#include <stdint.h>
#include "bitstream.h"
#include "put_bits.h"
#define INVALID_VLC 0x80000000
extern const uint8_t ff_golomb_vlc_len[512];
extern const uint8_t ff_ue_golomb_vlc_code[512];
extern const int8_t ff_se_golomb_vlc_code[512];
extern const uint8_t ff_ue_golomb_len[256];
extern const uint8_t ff_interleaved_golomb_vlc_len[256];
extern const uint8_t ff_interleaved_ue_golomb_vlc_code[256];
extern const int8_t ff_interleaved_se_golomb_vlc_code[256];
extern const uint8_t ff_interleaved_dirac_golomb_vlc_code[256];
/**
* read unsigned exp golomb code.
*/
static inline int get_ue_golomb(BitstreamContext *bc)
{
unsigned int buf;
buf = bitstream_peek(bc, 32);
if (buf >= (1 << 27)) {
buf >>= 32 - 9;
bitstream_skip(bc, ff_golomb_vlc_len[buf]);
return ff_ue_golomb_vlc_code[buf];
} else {
int log = 2 * av_log2(buf) - 31;
buf >>= log;
buf--;
bitstream_skip(bc, 32 - log);
return buf;
}
}
/**
* Read an unsigned Exp-Golomb code in the range 0 to UINT32_MAX-1.
*/
static inline unsigned get_ue_golomb_long(BitstreamContext *bc)
{
unsigned buf, log;
buf = bitstream_peek(bc, 32);
log = 31 - av_log2(buf);
bitstream_skip(bc, log);
return bitstream_read(bc, log + 1) - 1;
}
/**
* read unsigned exp golomb code, constraint to a max of 31.
* the return value is undefined if the stored value exceeds 31.
*/
static inline int get_ue_golomb_31(BitstreamContext *bc)
{
unsigned int buf;
buf = bitstream_peek(bc, 32);
buf >>= 32 - 9;
bitstream_skip(bc, ff_golomb_vlc_len[buf]);
return ff_ue_golomb_vlc_code[buf];
}
static inline unsigned get_interleaved_ue_golomb(BitstreamContext *bc)
{
uint32_t buf;
buf = bitstream_peek(bc, 32);
if (buf & 0xAA800000) {
buf >>= 32 - 8;
bitstream_skip(bc, ff_interleaved_golomb_vlc_len[buf]);
return ff_interleaved_ue_golomb_vlc_code[buf];
} else {
unsigned ret = 1;
do {
buf >>= 32 - 8;
bitstream_skip(bc, FFMIN(ff_interleaved_golomb_vlc_len[buf], 8));
if (ff_interleaved_golomb_vlc_len[buf] != 9) {
ret <<= (ff_interleaved_golomb_vlc_len[buf] - 1) >> 1;
ret |= ff_interleaved_dirac_golomb_vlc_code[buf];
break;
}
ret = (ret << 4) | ff_interleaved_dirac_golomb_vlc_code[buf];
buf = bitstream_peek(bc, 32);
} while (bitstream_bits_left(bc) > 0);
return ret - 1;
}
}
/**
* read unsigned truncated exp golomb code.
*/
static inline int get_te0_golomb(BitstreamContext *bc, int range)
{
assert(range >= 1);
if (range == 1)
return 0;
else if (range == 2)
return bitstream_read_bit(bc) ^ 1;
else
return get_ue_golomb(bc);
}
/**
* read unsigned truncated exp golomb code.
*/
static inline int get_te_golomb(BitstreamContext *bc, int range)
{
assert(range >= 1);
if (range == 2)
return bitstream_read_bit(bc) ^ 1;
else
return get_ue_golomb(bc);
}
/**
* read signed exp golomb code.
*/
static inline int get_se_golomb(BitstreamContext *bc)
{
unsigned int buf;
buf = bitstream_peek(bc, 32);
if (buf >= (1 << 27)) {
buf >>= 32 - 9;
bitstream_skip(bc, ff_golomb_vlc_len[buf]);
return ff_se_golomb_vlc_code[buf];
} else {
int log = 2 * av_log2(buf) - 31;
buf >>= log;
bitstream_skip(bc, 32 - log);
if (buf & 1)
buf = -(buf >> 1);
else
buf = (buf >> 1);
return buf;
}
}
static inline int get_se_golomb_long(BitstreamContext *bc)
{
unsigned int buf = get_ue_golomb_long(bc);
if (buf & 1)
buf = (buf + 1) >> 1;
else
buf = -(buf >> 1);
return buf;
}
static inline int get_interleaved_se_golomb(BitstreamContext *bc)
{
unsigned int buf;
buf = bitstream_peek(bc, 32);
if (buf & 0xAA800000) {
buf >>= 32 - 8;
bitstream_skip(bc, ff_interleaved_golomb_vlc_len[buf]);
return ff_interleaved_se_golomb_vlc_code[buf];
} else {
int log;
bitstream_skip(bc, 8);
buf |= 1 | bitstream_peek(bc, 24);
if ((buf & 0xAAAAAAAA) == 0)
return INVALID_VLC;
for (log = 31; (buf & 0x80000000) == 0; log--)
buf = (buf << 2) - ((buf << log) >> (log - 1)) + (buf >> 30);
bitstream_skip(bc, 63 - 2 * log - 8);
return (signed) (((((buf << log) >> log) - 1) ^ -(buf & 0x1)) + 1) >> 1;
}
}
static inline int dirac_get_se_golomb(BitstreamContext *bc)
{
uint32_t ret = get_interleaved_ue_golomb(bc);
if (ret) {
uint32_t buf;
buf = bitstream_read_signed(bc, 1);
ret = (ret ^ buf) - buf;
}
return ret;
}
/**
* read unsigned golomb rice code (ffv1).
*/
static inline int get_ur_golomb(BitstreamContext *bc, int k, int limit,
int esc_len)
{
unsigned int buf;
int log;
buf = bitstream_peek(bc, 32);
log = av_log2(buf);
if (log > 31 - limit) {
buf >>= log - k;
buf += (30 - log) << k;
bitstream_skip(bc, 32 + k - log);
return buf;
} else {
bitstream_skip(bc, limit);
buf = bitstream_read(bc, esc_len);
return buf + limit - 1;
}
}
/**
* read unsigned golomb rice code (jpegls).
*/
static inline int get_ur_golomb_jpegls(BitstreamContext *bc, int k, int limit,
int esc_len)
{
unsigned int buf;
int log;
buf = bitstream_peek(bc, 32);
log = av_log2(buf);
if (log - k >= 1 && 32 - log < limit) {
buf >>= log - k;
buf += (30 - log) << k;
bitstream_skip(bc, 32 + k - log);
return buf;
} else {
int i;
for (i = 0;
i < limit && bitstream_read_bit(bc) == 0 && bitstream_bits_left(bc) > 0;
i++);
if (i < limit - 1) {
buf = bitstream_read(bc, k);
return buf + (i << k);
} else if (i == limit - 1) {
buf = bitstream_read(bc, esc_len);
return buf + 1;
} else
return -1;
}
}
/**
* read signed golomb rice code (ffv1).
*/
static inline int get_sr_golomb(BitstreamContext *bc, int k, int limit,
int esc_len)
{
int v = get_ur_golomb(bc, k, limit, esc_len);
v++;
if (v & 1)
return v >> 1;
else
return -(v >> 1);
// return (v>>1) ^ -(v&1);
}
/**
* read signed golomb rice code (flac).
*/
static inline int get_sr_golomb_flac(BitstreamContext *bc, int k, int limit,
int esc_len)
{
int v = get_ur_golomb_jpegls(bc, k, limit, esc_len);
return (v >> 1) ^ -(v & 1);
}
/**
* read unsigned golomb rice code (shorten).
*/
static inline unsigned int get_ur_golomb_shorten(BitstreamContext *bc, int k)
{
return get_ur_golomb_jpegls(bc, k, INT_MAX, 0);
}
/**
* read signed golomb rice code (shorten).
*/
static inline int get_sr_golomb_shorten(BitstreamContext *bc, int k)
{
int uvar = get_ur_golomb_jpegls(bc, k + 1, INT_MAX, 0);
if (uvar & 1)
return ~(uvar >> 1);
else
return uvar >> 1;
}
#ifdef TRACE
static inline int get_ue(BitstreamContext *s, const char *file, const char *func,
int line)
{
int show = bitstream_peek(s, 24);
int pos = bitstream_tell(s);
int i = get_ue_golomb(s);
int len = bitstream_tell(s) - pos;
int bits = show >> (24 - len);
av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d ue @%5d in %s %s:%d\n",
bits, len, i, pos, file, func, line);
return i;
}
static inline int get_se(BitstreamContext *s, const char *file, const char *func,
int line)
{
int show = bitstream_peek(s, 24);
int pos = bitstream_tell(s);
int i = get_se_golomb(s);
int len = bitstream_tell(s) - pos;
int bits = show >> (24 - len);
av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d se @%5d in %s %s:%d\n",
bits, len, i, pos, file, func, line);
return i;
}
static inline int get_te(BitstreamContext *s, int r, char *file, const char *func,
int line)
{
int show = bitstream_peek(s, 24);
int pos = bitstream_tell(s);
int i = get_te0_golomb(s, r);
int len = bitstream_tell(s) - pos;
int bits = show >> (24 - len);
av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d te @%5d in %s %s:%d\n",
bits, len, i, pos, file, func, line);
return i;
}
#define get_ue_golomb(a) get_ue(a, __FILE__, __func__, __LINE__)
#define get_se_golomb(a) get_se(a, __FILE__, __func__, __LINE__)
#define get_te_golomb(a, r) get_te(a, r, __FILE__, __func__, __LINE__)
#define get_te0_golomb(a, r) get_te(a, r, __FILE__, __func__, __LINE__)
#endif /* TRACE */
/**
* write unsigned exp golomb code.
*/
static inline void set_ue_golomb(PutBitContext *pb, int i)
{
assert(i >= 0);
if (i < 256)
put_bits(pb, ff_ue_golomb_len[i], i + 1);
else {
int e = av_log2(i + 1);
put_bits(pb, 2 * e + 1, i + 1);
}
}
/**
* write truncated unsigned exp golomb code.
*/
static inline void set_te_golomb(PutBitContext *pb, int i, int range)
{
assert(range >= 1);
assert(i <= range);
if (range == 2)
put_bits(pb, 1, i ^ 1);
else
set_ue_golomb(pb, i);
}
/**
* write signed exp golomb code. 16 bits at most.
*/
static inline void set_se_golomb(PutBitContext *pb, int i)
{
i = 2 * i - 1;
if (i < 0)
i ^= -1; //FIXME check if gcc does the right thing
set_ue_golomb(pb, i);
}
/**
* write unsigned golomb rice code (ffv1).
*/
static inline void set_ur_golomb(PutBitContext *pb, int i, int k, int limit,
int esc_len)
{
int e;
assert(i >= 0);
e = i >> k;
if (e < limit)
put_bits(pb, e + k + 1, (1 << k) + (i & ((1 << k) - 1)));
else
put_bits(pb, limit + esc_len, i - limit + 1);
}
/**
* write unsigned golomb rice code (jpegls).
*/
static inline void set_ur_golomb_jpegls(PutBitContext *pb, int i, int k,
int limit, int esc_len)
{
int e;
assert(i >= 0);
e = (i >> k) + 1;
if (e < limit) {
while (e > 31) {
put_bits(pb, 31, 0);
e -= 31;
}
put_bits(pb, e, 1);
if (k)
put_sbits(pb, k, i);
} else {
while (limit > 31) {
put_bits(pb, 31, 0);
limit -= 31;
}
put_bits(pb, limit, 1);
put_bits(pb, esc_len, i - 1);
}
}
/**
* write signed golomb rice code (ffv1).
*/
static inline void set_sr_golomb(PutBitContext *pb, int i, int k, int limit,
int esc_len)
{
int v;
v = -2 * i - 1;
v ^= (v >> 31);
set_ur_golomb(pb, v, k, limit, esc_len);
}
/**
* write signed golomb rice code (flac).
*/
static inline void set_sr_golomb_flac(PutBitContext *pb, int i, int k,
int limit, int esc_len)
{
int v;
v = -2 * i - 1;
v ^= (v >> 31);
set_ur_golomb_jpegls(pb, v, k, limit, esc_len);
}
#endif /* AVCODEC_GOLOMB_H */
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