v4l2-hantro-h264-encoder/bitstream.c at master · bootlin/v4l2-hantro-h264-encoder · GitHub

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
/*
 * Copyright (C) 2020 Bootlin
 */

#include <stdlib.h>
#include <stdint.h>
#include <errno.h>
#include <string.h>

#include <bitstream.h>

struct bitstream *bitstream_create(void)
{
	struct bitstream *bitstream = NULL;

	bitstream = calloc(1, sizeof(*bitstream));
	if (!bitstream)
		goto error;

	bitstream->length = 1024;
	bitstream->buffer = calloc(1, bitstream->length);
	if (!bitstream->buffer)
		goto error;

	return bitstream;

error:
	if (bitstream) {
		if (bitstream->buffer)
			free(bitstream->buffer);

		free(bitstream);
	}

	return NULL;
}

void bitstream_destroy(struct bitstream *bitstream)
{
	if (!bitstream)
		return;

	if (bitstream->buffer)
		free(bitstream->buffer);

	free(bitstream);
}

int bitstream_reset(struct bitstream *bitstream)
{
	if (!bitstream)
		return -EINVAL;

	memset(bitstream->buffer, 0, bitstream->length);

	bitstream->offset_bytes = 0;
	bitstream->offset_bits = 0;

	return 0;
}

int bitstream_append_bits(struct bitstream *bitstream, uint32_t bits,
			  unsigned int bits_count)
{
	uint8_t *buffer;
	unsigned int buffer_bits_left;
	unsigned int bits_left = bits_count;
	unsigned int bits_offset = 0;

	if (!bitstream || bits_count > 32)
		return -EINVAL;

	buffer = bitstream->buffer + bitstream->offset_bytes;

	while (bits_left > 0) {
		uint32_t chunk;
		uint32_t base;
		uint32_t shift;
		uint32_t bits_masked;

		buffer = bitstream->buffer + bitstream->offset_bytes;

		buffer_bits_left = 8 - bitstream->offset_bits;
		chunk = bits_left < buffer_bits_left ? bits_left : buffer_bits_left;

		base = (1 << chunk) - 1;
		shift = bits_count - bits_offset - chunk;
		bits_masked = (bits & (base << shift)) >> shift;
		*buffer |= bits_masked << (8 - bitstream->offset_bits - chunk);

		bitstream->offset_bits += chunk;
		bits_left -= chunk;
		bits_offset += chunk;

		bitstream->offset_bytes += bitstream->offset_bits / 8;
		bitstream->offset_bits = bitstream->offset_bits % 8;
	}

	return 0;
}

int bitstream_append_ue(struct bitstream *bitstream, uint32_t value)
{
	uint32_t value_bit_count = 0;
	uint32_t zero_bit_count;

	if (value >= 0x7fffffff)
		return -EINVAL;

	value++;

	while (value >> value_bit_count)
		value_bit_count++;

	zero_bit_count = value_bit_count - 1;

	bitstream_append_bits(bitstream, 0, zero_bit_count);
	bitstream_append_bits(bitstream, value, value_bit_count);

	return 0;
}

int bitstream_append_se(struct bitstream *bitstream, int32_t value)
{
	uint32_t value_ue;

	if (value > 0)
		value_ue = (uint32_t)(2 * value - 1);
	else
		value_ue = (uint32_t)(-2 * value);

	return bitstream_append_ue(bitstream, value_ue);
}

int bitstream_align(struct bitstream *bitstream)
{
	if (!bitstream->offset_bits)
		return 0;

	bitstream_append_bits(bitstream, 0, 8 - bitstream->offset_bits);

	return 0;
}