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
43struct vl_rbsp {
44   struct vl_vlc nal;
45   unsigned escaped;
46};
47
48/**
49 * Initialize the RBSP object
50 */
51static 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 */
86static 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 */
123static 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 */
135static 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 */
149static 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 */
161static 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