1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
|
/*
* Copyright 2023 Red Hat
* SPDX-License-Identifier: MIT
*
* This is a C rewrite of pieces of the d3d12 frontend which is:
* Copyright © Microsoft Corporation
*/
#ifndef VL_BITSTREAM_H
#define VL_BITSTREAM_H
struct vl_bitstream_encoder {
uint8_t *bits;
uint32_t bits_buffer_size;
uint32_t offset;
uint32_t enc_buffer;
int32_t bits_to_go;
bool prevent_start_code;
bool internal_buffer;
bool overflow;
};
#define VL_BITSTREAM_MAX_BUFFER 256
static inline void
vl_bitstream_encoder_clear(struct vl_bitstream_encoder *enc,
void *buffer_base,
size_t buffer_offset,
size_t buffer_limit)
{
memset(enc, 0, sizeof(*enc));
enc->bits_to_go = 32;
if (!buffer_base) {
enc->bits = malloc(VL_BITSTREAM_MAX_BUFFER);
enc->bits_buffer_size = VL_BITSTREAM_MAX_BUFFER;
enc->internal_buffer = true;
} else {
enc->bits = (uint8_t *)buffer_base + buffer_offset;
enc->bits_buffer_size = buffer_limit;
}
}
static inline void
vl_bitstream_encoder_free(struct vl_bitstream_encoder *enc)
{
if (enc->internal_buffer)
free(enc->bits);
}
static inline int
vl_bitstream_get_num_bits_for_byte_align(struct vl_bitstream_encoder *enc)
{
return enc->bits_to_go & 7;
}
static inline int
vl_bitstream_get_byte_count(struct vl_bitstream_encoder *enc)
{
return enc->offset + ((32 - enc->bits_to_go) >> 3);
}
static inline bool
vl_bitstream_is_byte_aligned(struct vl_bitstream_encoder *enc)
{
if (enc->overflow)
enc->bits_to_go = 32;
return !(enc->bits_to_go & 7);
}
static inline void
vl_bitstream_write_byte_start_code(struct vl_bitstream_encoder *enc, uint8_t val)
{
int offset = enc->offset;
uint8_t *buffer = enc->bits + enc->offset;
if (enc->prevent_start_code && enc->offset > 1) {
if (((val & 0xfc) | buffer[-2] | buffer[-1]) == 0) {
*buffer++ = 3;
offset++;
}
}
*buffer = val;
offset++;
enc->offset = offset;
}
static inline bool
vl_bitstream_verify_buffer(struct vl_bitstream_encoder *enc, uint32_t bytes_to_write)
{
if (enc->overflow)
return false;
if (enc->offset + bytes_to_write > enc->bits_buffer_size) {
enc->overflow = true;
return false;
}
return true;
}
static inline void
vl_bitstream_flush(struct vl_bitstream_encoder *enc)
{
ASSERTED bool is_aligned = vl_bitstream_is_byte_aligned(enc);
assert (is_aligned);
uint32_t temp = (uint32_t)(32 - enc->bits_to_go);
if (!vl_bitstream_verify_buffer(enc, temp >> 3)) {
return;
}
while (temp > 0) {
vl_bitstream_write_byte_start_code(enc, (uint8_t)(enc->enc_buffer >> 24));
enc->enc_buffer <<= 8;
temp -= 8;
}
enc->bits_to_go = 32;
enc->enc_buffer = 0;
}
static inline void
vl_bitstream_put_bits(struct vl_bitstream_encoder *enc, int bits_count, uint32_t bits_val)
{
if (bits_count < enc->bits_to_go) {
enc->enc_buffer |= (bits_val << (enc->bits_to_go - bits_count));
enc->bits_to_go -= bits_count;
} else if (vl_bitstream_verify_buffer(enc, 4)) {
int left_over_bits = bits_count - enc->bits_to_go;
enc->enc_buffer |= (bits_val >> left_over_bits);
{
uint8_t *temp = (uint8_t *)&enc->enc_buffer;
vl_bitstream_write_byte_start_code(enc, *(temp + 3));
vl_bitstream_write_byte_start_code(enc, *(temp + 2));
vl_bitstream_write_byte_start_code(enc, *(temp + 1));
vl_bitstream_write_byte_start_code(enc, *temp);
}
enc->enc_buffer = 0;
enc->bits_to_go = 32 - left_over_bits;
if (left_over_bits > 0)
enc->enc_buffer = (bits_val << (32 - left_over_bits));
}
}
static inline void
vl_bitstream_put_uvlc(struct vl_bitstream_encoder *enc, uint64_t val)
{
uint32_t num_bits = 0;
uint64_t value_plus1 = (uint64_t)val + 1;
uint32_t num_leading_zeros = 0;
while ((uint64_t)1 << num_bits <= value_plus1)
num_bits++;
num_leading_zeros = num_bits - 1;
vl_bitstream_put_bits(enc, num_leading_zeros, 0);
vl_bitstream_put_bits(enc, 1, 1);
vl_bitstream_put_bits(enc, num_leading_zeros, (uint32_t)value_plus1);
}
static inline int
vl_bitstream_get_exp_golomb0_code_len(uint32_t val)
{
int len = 0;
val++;
if (val >= 0x10000) {
val >>= 16;
len += 16;
}
if (val >= 0x100) {
val >>= 8;
len += 8;
}
assert(val < 256);
return len + util_logbase2(val);
}
static inline void
vl_bitstream_exp_golomb_ue(struct vl_bitstream_encoder *enc, uint32_t val)
{
if (val != UINT32_MAX) {
int len = vl_bitstream_get_exp_golomb0_code_len(val);
vl_bitstream_put_bits(enc, (len << 1) + 1, val + 1);
} else {
vl_bitstream_put_bits(enc, 32, 0);
vl_bitstream_put_bits(enc, 1, 1);
vl_bitstream_put_bits(enc, 32, 1);
}
}
static inline void
vl_bitstream_exp_golomb_se(struct vl_bitstream_encoder *enc, int32_t val)
{
if (val > 0)
vl_bitstream_exp_golomb_ue(enc, (val << 1) - 1);
else
vl_bitstream_exp_golomb_ue(enc, ((-val) << 1) - (val == INT_MIN));
}
static inline void
vl_bitstream_rbsp_trailing(struct vl_bitstream_encoder *enc)
{
vl_bitstream_put_bits(enc, 1, 1);
int left = vl_bitstream_get_num_bits_for_byte_align(enc);
if (left)
vl_bitstream_put_bits(enc, left, 0);
ASSERTED bool is_aligned = vl_bitstream_is_byte_aligned(enc);
assert(is_aligned);
}
static inline uint8_t*
vl_bitstream_get_byte_offset(struct vl_bitstream_encoder *enc)
{
ASSERTED bool is_aligned = vl_bitstream_is_byte_aligned(enc);
assert(is_aligned);
return enc->bits + (enc->offset + ((32 - enc->bits_to_go) >> 3));
}
#endif
|
