1 /**************************************************************************
2 *
3 * Copyright 2013 Advanced Micro Devices, Inc.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
21 * IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR
22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27
28 /*
29 * Authors:
30 * Christian König <christian.koenig@amd.com>
31 *
32 */
33
34 /*
35 * Functions for reading the raw byte sequence payload of H.264
36 */
37
38 #ifndef vl_rbsp_h
39 #define vl_rbsp_h
40
41 #include "util/vl_vlc.h"
42
43 struct vl_rbsp {
44 struct vl_vlc nal;
45 unsigned escaped;
46 unsigned removed;
47 };
48
49 /**
50 * Initialize the RBSP object
51 */
vl_rbsp_init(struct vl_rbsp * rbsp,struct vl_vlc * nal,unsigned num_bits)52 static inline void vl_rbsp_init(struct vl_rbsp *rbsp, struct vl_vlc *nal, unsigned num_bits)
53 {
54 unsigned valid, bits_left = vl_vlc_bits_left(nal);
55 int i;
56
57 /* copy the position */
58 rbsp->nal = *nal;
59
60 /* search for the end of the NAL unit */
61 while (vl_vlc_search_byte(nal, num_bits, 0x00)) {
62 if (vl_vlc_peekbits(nal, 24) == 0x000001 ||
63 vl_vlc_peekbits(nal, 32) == 0x00000001) {
64 vl_vlc_limit(&rbsp->nal, bits_left - vl_vlc_bits_left(nal));
65 break;
66 }
67 vl_vlc_eatbits(nal, 8);
68 }
69
70 valid = vl_vlc_valid_bits(&rbsp->nal);
71 /* search for the emulation prevention three byte */
72 for (i = 24; i <= valid; i += 8) {
73 if ((vl_vlc_peekbits(&rbsp->nal, i) & 0xffffff) == 0x3) {
74 vl_vlc_removebits(&rbsp->nal, i - 8, 8);
75 i += 8;
76 }
77 }
78
79 valid = vl_vlc_valid_bits(&rbsp->nal);
80
81 rbsp->escaped = (valid >= 16) ? 16 : ((valid >= 8) ? 8 : 0);
82 rbsp->removed = 0;
83 }
84
85 /**
86 * Make at least 16 more bits available
87 */
vl_rbsp_fillbits(struct vl_rbsp * rbsp)88 static inline void vl_rbsp_fillbits(struct vl_rbsp *rbsp)
89 {
90 unsigned valid = vl_vlc_valid_bits(&rbsp->nal);
91 unsigned i, bits;
92
93 /* abort if we still have enough bits */
94 if (valid >= 32)
95 return;
96
97 vl_vlc_fillbits(&rbsp->nal);
98
99 /* abort if we have less than 24 bits left in this nal */
100 if (vl_vlc_bits_left(&rbsp->nal) < 24)
101 return;
102
103 /* check that we have enough bits left from the last fillbits */
104 assert(valid >= rbsp->escaped);
105
106 /* handle the already escaped bits */
107 valid -= rbsp->escaped;
108
109 /* search for the emulation prevention three byte */
110 rbsp->escaped = 16;
111 bits = vl_vlc_valid_bits(&rbsp->nal);
112 for (i = valid + 24; i <= bits; i += 8) {
113 if ((vl_vlc_peekbits(&rbsp->nal, i) & 0xffffff) == 0x3) {
114 vl_vlc_removebits(&rbsp->nal, i - 8, 8);
115 rbsp->escaped = bits - i;
116 bits -= 8;
117 rbsp->removed += 8;
118 i += 8;
119 }
120 }
121 }
122
123 /**
124 * Return an unsigned integer from the first n bits
125 */
vl_rbsp_u(struct vl_rbsp * rbsp,unsigned n)126 static inline unsigned vl_rbsp_u(struct vl_rbsp *rbsp, unsigned n)
127 {
128 if (n == 0)
129 return 0;
130
131 vl_rbsp_fillbits(rbsp);
132 return vl_vlc_get_uimsbf(&rbsp->nal, n);
133 }
134
135 /**
136 * Return an unsigned exponential Golomb encoded integer
137 */
vl_rbsp_ue(struct vl_rbsp * rbsp)138 static inline unsigned vl_rbsp_ue(struct vl_rbsp *rbsp)
139 {
140 unsigned bits = 0;
141
142 vl_rbsp_fillbits(rbsp);
143 while (!vl_vlc_get_uimsbf(&rbsp->nal, 1))
144 ++bits;
145
146 return (1 << bits) - 1 + vl_rbsp_u(rbsp, bits);
147 }
148
149 /**
150 * Return an signed exponential Golomb encoded integer
151 */
vl_rbsp_se(struct vl_rbsp * rbsp)152 static inline signed vl_rbsp_se(struct vl_rbsp *rbsp)
153 {
154 signed codeNum = vl_rbsp_ue(rbsp);
155 if (codeNum & 1)
156 return (codeNum + 1) >> 1;
157 else
158 return -(codeNum >> 1);
159 }
160
161 /**
162 * Are more data available in the RBSP ?
163 */
vl_rbsp_more_data(struct vl_rbsp * rbsp)164 static inline bool vl_rbsp_more_data(struct vl_rbsp *rbsp)
165 {
166 unsigned bits, value;
167
168 if (vl_vlc_bits_left(&rbsp->nal) > 8)
169 return true;
170
171 bits = vl_vlc_valid_bits(&rbsp->nal);
172 value = vl_vlc_peekbits(&rbsp->nal, bits);
173 if (value == 0 || value == (1 << (bits - 1)))
174 return false;
175
176 return true;
177 }
178
179 #endif /* vl_rbsp_h */
180