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 "vl/vl_vlc.h"
42
43 struct vl_rbsp {
44 struct vl_vlc nal;
45 unsigned escaped;
46 };
47
48 /**
49 * Initialize the RBSP object
50 */
vl_rbsp_init(struct vl_rbsp * rbsp,struct vl_vlc * nal,unsigned num_bits)51 static inline void vl_rbsp_init(struct vl_rbsp *rbsp, struct vl_vlc *nal, unsigned num_bits)
52 {
53 unsigned valid, bits_left = vl_vlc_bits_left(nal);
54 int i;
55
56 /* copy the position */
57 rbsp->nal = *nal;
58
59 /* search for the end of the NAL unit */
60 while (vl_vlc_search_byte(nal, num_bits, 0x00)) {
61 if (vl_vlc_peekbits(nal, 24) == 0x000001 ||
62 vl_vlc_peekbits(nal, 32) == 0x00000001) {
63 vl_vlc_limit(&rbsp->nal, bits_left - vl_vlc_bits_left(nal));
64 break;
65 }
66 vl_vlc_eatbits(nal, 8);
67 }
68
69 valid = vl_vlc_valid_bits(&rbsp->nal);
70 /* search for the emulation prevention three byte */
71 for (i = 24; i <= valid; i += 8) {
72 if ((vl_vlc_peekbits(&rbsp->nal, i) & 0xffffff) == 0x3) {
73 vl_vlc_removebits(&rbsp->nal, i - 8, 8);
74 i += 8;
75 }
76 }
77
78 valid = vl_vlc_valid_bits(&rbsp->nal);
79
80 rbsp->escaped = (valid >= 16) ? 16 : ((valid >= 8) ? 8 : 0);
81 }
82
83 /**
84 * Make at least 16 more bits available
85 */
vl_rbsp_fillbits(struct vl_rbsp * rbsp)86 static inline void vl_rbsp_fillbits(struct vl_rbsp *rbsp)
87 {
88 unsigned valid = vl_vlc_valid_bits(&rbsp->nal);
89 unsigned i, bits;
90
91 /* abort if we still have enough bits */
92 if (valid >= 32)
93 return;
94
95 vl_vlc_fillbits(&rbsp->nal);
96
97 /* abort if we have less than 24 bits left in this nal */
98 if (vl_vlc_bits_left(&rbsp->nal) < 24)
99 return;
100
101 /* check that we have enough bits left from the last fillbits */
102 assert(valid >= rbsp->escaped);
103
104 /* handle the already escaped bits */
105 valid -= rbsp->escaped;
106
107 /* search for the emulation prevention three byte */
108 rbsp->escaped = 16;
109 bits = vl_vlc_valid_bits(&rbsp->nal);
110 for (i = valid + 24; i <= bits; i += 8) {
111 if ((vl_vlc_peekbits(&rbsp->nal, i) & 0xffffff) == 0x3) {
112 vl_vlc_removebits(&rbsp->nal, i - 8, 8);
113 rbsp->escaped = bits - i;
114 bits -= 8;
115 i += 8;
116 }
117 }
118 }
119
120 /**
121 * Return an unsigned integer from the first n bits
122 */
vl_rbsp_u(struct vl_rbsp * rbsp,unsigned n)123 static inline unsigned vl_rbsp_u(struct vl_rbsp *rbsp, unsigned n)
124 {
125 if (n == 0)
126 return 0;
127
128 vl_rbsp_fillbits(rbsp);
129 return vl_vlc_get_uimsbf(&rbsp->nal, n);
130 }
131
132 /**
133 * Return an unsigned exponential Golomb encoded integer
134 */
vl_rbsp_ue(struct vl_rbsp * rbsp)135 static inline unsigned vl_rbsp_ue(struct vl_rbsp *rbsp)
136 {
137 unsigned bits = 0;
138
139 vl_rbsp_fillbits(rbsp);
140 while (!vl_vlc_get_uimsbf(&rbsp->nal, 1))
141 ++bits;
142
143 return (1 << bits) - 1 + vl_rbsp_u(rbsp, bits);
144 }
145
146 /**
147 * Return an signed exponential Golomb encoded integer
148 */
vl_rbsp_se(struct vl_rbsp * rbsp)149 static inline signed vl_rbsp_se(struct vl_rbsp *rbsp)
150 {
151 signed codeNum = vl_rbsp_ue(rbsp);
152 if (codeNum & 1)
153 return (codeNum + 1) >> 1;
154 else
155 return -(codeNum >> 1);
156 }
157
158 /**
159 * Are more data available in the RBSP ?
160 */
vl_rbsp_more_data(struct vl_rbsp * rbsp)161 static inline bool vl_rbsp_more_data(struct vl_rbsp *rbsp)
162 {
163 unsigned bits, value;
164
165 if (vl_vlc_bits_left(&rbsp->nal) > 8)
166 return TRUE;
167
168 bits = vl_vlc_valid_bits(&rbsp->nal);
169 value = vl_vlc_peekbits(&rbsp->nal, bits);
170 if (value == 0 || value == (1 << (bits - 1)))
171 return FALSE;
172
173 return TRUE;
174 }
175
176 #endif /* vl_rbsp_h */
177