2 * H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder
3 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * Context Adaptive Binary Arithmetic Coder inline functions
27 #ifndef AVCODEC_CABAC_FUNCTIONS_H
28 #define AVCODEC_CABAC_FUNCTIONS_H
35 #ifndef UNCHECKED_BITSTREAM_READER
36 #define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER
40 # include "aarch64/cabac.h"
43 # include "arm/cabac.h"
46 # include "x86/cabac.h"
49 static CABAC_TABLE_CONST
uint8_t * const ff_h264_norm_shift
= ff_h264_cabac_tables
+ H264_NORM_SHIFT_OFFSET
;
50 static CABAC_TABLE_CONST
uint8_t * const ff_h264_lps_range
= ff_h264_cabac_tables
+ H264_LPS_RANGE_OFFSET
;
51 static CABAC_TABLE_CONST
uint8_t * const ff_h264_mlps_state
= ff_h264_cabac_tables
+ H264_MLPS_STATE_OFFSET
;
52 static CABAC_TABLE_CONST
uint8_t * const ff_h264_last_coeff_flag_offset_8x8
= ff_h264_cabac_tables
+ H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET
;
54 static void refill(CABACContext
*c
){
56 c
->low
+= (c
->bytestream
[0]<<9) + (c
->bytestream
[1]<<1);
58 c
->low
+= c
->bytestream
[0]<<1;
61 #if !UNCHECKED_BITSTREAM_READER
62 if (c
->bytestream
< c
->bytestream_end
)
64 c
->bytestream
+= CABAC_BITS
/ 8;
67 static inline void renorm_cabac_decoder_once(CABACContext
*c
){
68 int shift
= (uint32_t)(c
->range
- 0x100)>>31;
71 if(!(c
->low
& CABAC_MASK
))
75 #ifndef get_cabac_inline
76 static void refill2(CABACContext
*c
){
79 x
= c
->low
^ (c
->low
-1);
80 i
= 7 - ff_h264_norm_shift
[x
>>(CABAC_BITS
-1)];
85 x
+= (c
->bytestream
[0]<<9) + (c
->bytestream
[1]<<1);
87 x
+= c
->bytestream
[0]<<1;
91 #if !UNCHECKED_BITSTREAM_READER
92 if (c
->bytestream
< c
->bytestream_end
)
94 c
->bytestream
+= CABAC_BITS
/8;
97 static av_always_inline
int get_cabac_inline(CABACContext
*c
, uint8_t * const state
){
99 int RangeLPS
= ff_h264_lps_range
[2*(c
->range
&0xC0) + s
];
102 c
->range
-= RangeLPS
;
103 lps_mask
= ((c
->range
<<(CABAC_BITS
+1)) - c
->low
)>>31;
105 c
->low
-= (c
->range
<<(CABAC_BITS
+1)) & lps_mask
;
106 c
->range
+= (RangeLPS
- c
->range
) & lps_mask
;
109 *state
= (ff_h264_mlps_state
+128)[s
];
112 lps_mask
= ff_h264_norm_shift
[c
->range
];
113 c
->range
<<= lps_mask
;
115 if(!(c
->low
& CABAC_MASK
))
121 static int av_noinline av_unused
get_cabac_noinline(CABACContext
*c
, uint8_t * const state
){
122 return get_cabac_inline(c
,state
);
125 static int av_unused
get_cabac(CABACContext
*c
, uint8_t * const state
){
126 return get_cabac_inline(c
,state
);
129 #ifndef get_cabac_bypass
130 static int av_unused
get_cabac_bypass(CABACContext
*c
){
134 if(!(c
->low
& CABAC_MASK
))
137 range
= c
->range
<<(CABAC_BITS
+1);
147 #ifndef get_cabac_bypass_sign
148 static av_always_inline
int get_cabac_bypass_sign(CABACContext
*c
, int val
){
152 if(!(c
->low
& CABAC_MASK
))
155 range
= c
->range
<<(CABAC_BITS
+1);
160 return (val
^mask
)-mask
;
166 * @return the number of bytes read or 0 if no end
168 static int av_unused
get_cabac_terminate(CABACContext
*c
){
170 if(c
->low
< c
->range
<<(CABAC_BITS
+1)){
171 renorm_cabac_decoder_once(c
);
174 return c
->bytestream
- c
->bytestream_start
;
179 * Skip @p n bytes and reset the decoder.
180 * @return the address of the first skipped byte or NULL if there's less than @p n bytes left
182 static av_unused
const uint8_t* skip_bytes(CABACContext
*c
, int n
) {
183 const uint8_t *ptr
= c
->bytestream
;
191 if ((int) (c
->bytestream_end
- ptr
) < n
)
193 ff_init_cabac_decoder(c
, ptr
+ n
, c
->bytestream_end
- ptr
- n
);
198 #endif /* AVCODEC_CABAC_FUNCTIONS_H */