/work/dav1d/src/getbits.h
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1 | | /* |
2 | | * Copyright © 2018, VideoLAN and dav1d authors |
3 | | * Copyright © 2018, Two Orioles, LLC |
4 | | * All rights reserved. |
5 | | * |
6 | | * Redistribution and use in source and binary forms, with or without |
7 | | * modification, are permitted provided that the following conditions are met: |
8 | | * |
9 | | * 1. Redistributions of source code must retain the above copyright notice, this |
10 | | * list of conditions and the following disclaimer. |
11 | | * |
12 | | * 2. Redistributions in binary form must reproduce the above copyright notice, |
13 | | * this list of conditions and the following disclaimer in the documentation |
14 | | * and/or other materials provided with the distribution. |
15 | | * |
16 | | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND |
17 | | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
18 | | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
19 | | * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR |
20 | | * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
21 | | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
22 | | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
23 | | * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
24 | | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
25 | | * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
26 | | */ |
27 | | |
28 | | #ifndef DAV1D_SRC_GETBITS_H |
29 | | #define DAV1D_SRC_GETBITS_H |
30 | | |
31 | | #include <stddef.h> |
32 | | #include <stdint.h> |
33 | | |
34 | | typedef struct GetBits { |
35 | | uint64_t state; |
36 | | int bits_left, error; |
37 | | const uint8_t *ptr, *ptr_start, *ptr_end; |
38 | | } GetBits; |
39 | | |
40 | | void dav1d_init_get_bits(GetBits *c, const uint8_t *data, size_t sz); |
41 | | unsigned dav1d_get_bit(GetBits *c); |
42 | | unsigned dav1d_get_bits(GetBits *c, int n); |
43 | | int dav1d_get_sbits(GetBits *c, int n); |
44 | | unsigned dav1d_get_uleb128(GetBits *c); |
45 | | |
46 | | // Output in range 0..max-1 |
47 | | unsigned dav1d_get_uniform(GetBits *c, unsigned max); |
48 | | unsigned dav1d_get_vlc(GetBits *c); |
49 | | int dav1d_get_bits_subexp(GetBits *c, int ref, unsigned n); |
50 | | |
51 | | // Discard bits from the buffer until we're next byte-aligned. |
52 | 0 | static inline void dav1d_bytealign_get_bits(GetBits *c) { |
53 | | // bits_left is never more than 7, because it is only incremented |
54 | | // by refill(), called by dav1d_get_bits and that never reads more |
55 | | // than 7 bits more than it needs. |
56 | | // |
57 | | // If this wasn't true, we would need to work out how many bits to |
58 | | // discard (bits_left % 8), subtract that from bits_left and then |
59 | | // shift state right by that amount. |
60 | 0 | assert(c->bits_left <= 7); |
61 | | |
62 | 0 | c->bits_left = 0; |
63 | 0 | c->state = 0; |
64 | 0 | } Unexecuted instantiation: obu.c:dav1d_bytealign_get_bits Unexecuted instantiation: getbits.c:dav1d_bytealign_get_bits |
65 | | |
66 | | // Return the current bit position relative to the start of the buffer. |
67 | 0 | static inline unsigned dav1d_get_bits_pos(const GetBits *c) { |
68 | 0 | return (unsigned) (c->ptr - c->ptr_start) * 8 - c->bits_left; |
69 | 0 | } Unexecuted instantiation: obu.c:dav1d_get_bits_pos Unexecuted instantiation: getbits.c:dav1d_get_bits_pos |
70 | | |
71 | | #endif /* DAV1D_SRC_GETBITS_H */ |