path: root/drivers/amvdec_ports/decoder/h264_stream.c (plain)
blob: 3061568309fc1975ddbaf4b22b04c3894777ded9

1	/*
2	* drivers/amlogic/media_modules/amvdec_ports/decoder/h264_stream.c
3	*
4	* Copyright (C) 2017 Amlogic, Inc. All rights reserved.
5	*
6	* This program is free software; you can redistribute it and/or modify
7	* it under the terms of the GNU General Public License as published by
8	* the Free Software Foundation; either version 2 of the License, or
9	* (at your option) any later version.
10	*
11	* This program is distributed in the hope that it will be useful, but WITHOUT
12	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
14	* more details.
15	*
16	*/
17
18	#include <linux/mm.h>
19	#include <linux/slab.h>
20	#include "h264_stream.h"
21
22	void h264_stream_set(struct h264_stream_t *s, unsigned char *data, int size)
23	{
24	s->data = data;
25	s->size = size;
26	s->bit_pos = 7;
27	s->byte_pos = 0;
28	}
29
30	unsigned int h264_stream_read_bits(struct h264_stream_t *s, unsigned int n)
31	{
32	unsigned int ret = 0;
33	unsigned char b = 0;
34	int i;
35
36	if (n == 0)
37	return 0;
38
39	for (i = 0; i < n; ++i) {
40	if (h264_stream_bits_remaining(s) == 0)
41	ret <<= n - i - 1;
42
43	b = s->data[s->byte_pos];
44	if (n - i <= 32)
45	ret = ret << 1 | BITAT(b, s->bit_pos);
46
47	if (s->bit_pos == 0) {
48	s->bit_pos = 7;
49	s->byte_pos++;
50	} else
51	s->bit_pos--;
52	}
53
54	return ret;
55	}
56
57	unsigned int h264_stream_peek_bits(struct h264_stream_t *s, unsigned int n)
58	{
59	int prev_bit_pos = s->bit_pos;
60	int prev_byte_pos = s->byte_pos;
61	unsigned int ret = h264_stream_read_bits(s, n);
62
63	s->bit_pos = prev_bit_pos;
64	s->byte_pos = prev_byte_pos;
65
66	return ret;
67	}
68
69	unsigned int h264_stream_read_bytes(struct h264_stream_t *s, unsigned int n)
70	{
71	unsigned int ret = 0;
72	int i;
73
74	if (n == 0)
75	return 0;
76
77	for (i = 0; i < n; ++i) {
78	if (h264_stream_bytes_remaining(s) == 0) {
79	ret <<= (n - i - 1) * 8;
80	break;
81	}
82
83	if (n - i <= 4)
84	ret = ret << 8 | s->data[s->byte_pos];
85
86	s->byte_pos++;
87	}
88
89	return ret;
90	}
91
92	unsigned int h264_stream_peek_bytes(struct h264_stream_t *s, unsigned int n)
93	{
94	int prev_byte_pos = s->byte_pos;
95	unsigned int ret = h264_stream_read_bytes(s, n);
96
97	s->byte_pos = prev_byte_pos;
98
99	return ret;
100	}
101
102	int h264_stream_bits_remaining(struct h264_stream_t *s)
103	{
104	return (s->size - s->byte_pos) * 8 + s->bit_pos;
105	}
106
107	int h264_stream_bytes_remaining(struct h264_stream_t *s)
108	{
109	return s->size - s->byte_pos;
110	}
111
112