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/**************************************************************************
*
* Copyright 2013 Advanced Micro Devices, Inc.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sub license, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
* IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR
* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
**************************************************************************/
/*
* Authors:
* Christian König <christian.koenig@amd.com>
*
*/
/*
* Functions for reading the raw byte sequence payload of H.264
*/
#ifndef vl_rbsp_h
#define vl_rbsp_h
#include "util/vl_vlc.h"
struct vl_rbsp {
struct vl_vlc nal;
unsigned escaped;
unsigned removed;
bool emulation_bytes;
};
/**
* Initialize the RBSP object
*/
static inline void vl_rbsp_init(struct vl_rbsp *rbsp, struct vl_vlc *nal, unsigned num_bits,
bool emulation_bytes)
{
unsigned valid, bits_left = vl_vlc_bits_left(nal);
int i;
/* copy the position */
rbsp->nal = *nal;
rbsp->escaped = 0;
rbsp->removed = 0;
rbsp->emulation_bytes = emulation_bytes;
if (!rbsp->emulation_bytes)
return;
/* search for the end of the NAL unit */
while (vl_vlc_search_byte(nal, num_bits, 0x00)) {
if (vl_vlc_peekbits(nal, 24) == 0x000001 ||
vl_vlc_peekbits(nal, 32) == 0x00000001) {
vl_vlc_limit(&rbsp->nal, bits_left - vl_vlc_bits_left(nal));
break;
}
vl_vlc_eatbits(nal, 8);
}
valid = vl_vlc_valid_bits(&rbsp->nal);
/* search for the emulation prevention three byte */
for (i = 24; i <= valid; i += 8) {
if ((vl_vlc_peekbits(&rbsp->nal, i) & 0xffffff) == 0x3) {
vl_vlc_removebits(&rbsp->nal, i - 8, 8);
i += 8;
}
}
valid = vl_vlc_valid_bits(&rbsp->nal);
rbsp->escaped = (valid >= 16) ? 16 : ((valid >= 8) ? 8 : 0);
}
/**
* Make at least 16 more bits available
*/
static inline void vl_rbsp_fillbits(struct vl_rbsp *rbsp)
{
unsigned valid = vl_vlc_valid_bits(&rbsp->nal);
unsigned i, bits;
/* abort if we still have enough bits */
if (valid >= 32)
return;
vl_vlc_fillbits(&rbsp->nal);
/* nothing to do if no emulation prevention bytes in bitstream */
if (!rbsp->emulation_bytes)
return;
/* abort if we have less than 24 bits left in this nal */
if (vl_vlc_bits_left(&rbsp->nal) < 24)
return;
/* handle the already escaped bits */
valid -= rbsp->escaped;
/* search for the emulation prevention three byte */
rbsp->escaped = 16;
bits = vl_vlc_valid_bits(&rbsp->nal);
for (i = valid + 24; i <= bits; i += 8) {
if ((vl_vlc_peekbits(&rbsp->nal, i) & 0xffffff) == 0x3) {
vl_vlc_removebits(&rbsp->nal, i - 8, 8);
rbsp->escaped = bits - i;
bits -= 8;
rbsp->removed += 8;
i += 8;
}
}
}
/**
* Return an unsigned integer from the first n bits
*/
static inline unsigned vl_rbsp_u(struct vl_rbsp *rbsp, unsigned n)
{
if (n == 0)
return 0;
vl_rbsp_fillbits(rbsp);
if (n > 16)
vl_rbsp_fillbits(rbsp);
return vl_vlc_get_uimsbf(&rbsp->nal, n);
}
/**
* Return an unsigned exponential Golomb encoded integer
*/
static inline unsigned vl_rbsp_ue(struct vl_rbsp *rbsp)
{
unsigned bits = 0;
vl_rbsp_fillbits(rbsp);
while (!vl_vlc_get_uimsbf(&rbsp->nal, 1))
++bits;
return (1 << bits) - 1 + vl_rbsp_u(rbsp, bits);
}
/**
* Return an signed exponential Golomb encoded integer
*/
static inline signed vl_rbsp_se(struct vl_rbsp *rbsp)
{
signed codeNum = vl_rbsp_ue(rbsp);
if (codeNum & 1)
return (codeNum + 1) >> 1;
else
return -(codeNum >> 1);
}
/**
* Are more data available in the RBSP ?
*/
static inline bool vl_rbsp_more_data(struct vl_rbsp *rbsp)
{
unsigned bits, value;
if (vl_vlc_bits_left(&rbsp->nal) > 8)
return true;
bits = vl_vlc_valid_bits(&rbsp->nal);
value = vl_vlc_peekbits(&rbsp->nal, bits);
if (value == 0 || value == (1 << (bits - 1)))
return false;
return true;
}
#endif /* vl_rbsp_h */
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