gpu_neon: fix some missing ebuf updates
[pcsx_rearmed.git] / deps / libchdr / src / libchdr_bitstream.c
CommitLineData
9c659ffe 1/* license:BSD-3-Clause
2 * copyright-holders:Aaron Giles
3***************************************************************************
ce188d4d 4
5 bitstream.c
6
7 Helper classes for reading/writing at the bit level.
8
9***************************************************************************/
10
ce188d4d 11#include <stdlib.h>
2ff0b512 12#include <libchdr/bitstream.h>
ce188d4d 13
9c659ffe 14/***************************************************************************
15 * INLINE FUNCTIONS
16 ***************************************************************************
17 */
ce188d4d 18
19int bitstream_overflow(struct bitstream* bitstream) { return ((bitstream->doffset - bitstream->bits / 8) > bitstream->dlength); }
20
9c659ffe 21/*-------------------------------------------------
22 * create_bitstream - constructor
23 *-------------------------------------------------
24 */
ce188d4d 25
26struct bitstream* create_bitstream(const void *src, uint32_t srclength)
27{
28 struct bitstream* bitstream = (struct bitstream*)malloc(sizeof(struct bitstream));
29 bitstream->buffer = 0;
30 bitstream->bits = 0;
31 bitstream->read = (const uint8_t*)src;
32 bitstream->doffset = 0;
33 bitstream->dlength = srclength;
34 return bitstream;
35}
36
37
9c659ffe 38/*-----------------------------------------------------
39 * bitstream_peek - fetch the requested number of bits
40 * but don't advance the input pointer
41 *-----------------------------------------------------
42 */
ce188d4d 43
44uint32_t bitstream_peek(struct bitstream* bitstream, int numbits)
45{
46 if (numbits == 0)
47 return 0;
48
9c659ffe 49 /* fetch data if we need more */
ce188d4d 50 if (numbits > bitstream->bits)
51 {
52 while (bitstream->bits <= 24)
53 {
54 if (bitstream->doffset < bitstream->dlength)
55 bitstream->buffer |= bitstream->read[bitstream->doffset] << (24 - bitstream->bits);
56 bitstream->doffset++;
57 bitstream->bits += 8;
58 }
59 }
60
9c659ffe 61 /* return the data */
ce188d4d 62 return bitstream->buffer >> (32 - numbits);
63}
64
65
9c659ffe 66/*-----------------------------------------------------
67 * bitstream_remove - advance the input pointer by the
68 * specified number of bits
69 *-----------------------------------------------------
70 */
ce188d4d 71
72void bitstream_remove(struct bitstream* bitstream, int numbits)
73{
74 bitstream->buffer <<= numbits;
75 bitstream->bits -= numbits;
76}
77
78
9c659ffe 79/*-----------------------------------------------------
80 * bitstream_read - fetch the requested number of bits
81 *-----------------------------------------------------
82 */
ce188d4d 83
84uint32_t bitstream_read(struct bitstream* bitstream, int numbits)
85{
86 uint32_t result = bitstream_peek(bitstream, numbits);
87 bitstream_remove(bitstream, numbits);
88 return result;
89}
90
91
9c659ffe 92/*-------------------------------------------------
93 * read_offset - return the current read offset
94 *-------------------------------------------------
95 */
ce188d4d 96
97uint32_t bitstream_read_offset(struct bitstream* bitstream)
98{
99 uint32_t result = bitstream->doffset;
100 int bits = bitstream->bits;
101 while (bits >= 8)
102 {
103 result--;
104 bits -= 8;
105 }
106 return result;
107}
108
109
9c659ffe 110/*-------------------------------------------------
111 * flush - flush to the nearest byte
112 *-------------------------------------------------
113 */
ce188d4d 114
115uint32_t bitstream_flush(struct bitstream* bitstream)
116{
117 while (bitstream->bits >= 8)
118 {
119 bitstream->doffset--;
120 bitstream->bits -= 8;
121 }
122 bitstream->bits = bitstream->buffer = 0;
123 return bitstream->doffset;
124}
125