1 /*
2 * Copyright (c) 2016, Alliance for Open Media. All rights reserved.
3 *
4 * This source code is subject to the terms of the BSD 2 Clause License and
5 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
6 * was not distributed with this source code in the LICENSE file, you can
7 * obtain it at www.aomedia.org/license/software. If the Alliance for Open
8 * Media Patent License 1.0 was not distributed with this source code in the
9 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
10 */
11
12 #include <assert.h>
13 #include <limits.h>
14 #include <stdlib.h>
15
16 #include "config/aom_config.h"
17
18 #include "aom_dsp/bitwriter_buffer.h"
19 #include "aom_dsp/recenter.h"
20 #include "aom_ports/bitops.h"
21
aom_wb_is_byte_aligned(const struct aom_write_bit_buffer * wb)22 int aom_wb_is_byte_aligned(const struct aom_write_bit_buffer *wb) {
23 return (wb->bit_offset % CHAR_BIT == 0);
24 }
25
aom_wb_bytes_written(const struct aom_write_bit_buffer * wb)26 uint32_t aom_wb_bytes_written(const struct aom_write_bit_buffer *wb) {
27 return wb->bit_offset / CHAR_BIT + (wb->bit_offset % CHAR_BIT > 0);
28 }
29
aom_wb_write_bit(struct aom_write_bit_buffer * wb,int bit)30 void aom_wb_write_bit(struct aom_write_bit_buffer *wb, int bit) {
31 const int off = (int)wb->bit_offset;
32 const int p = off / CHAR_BIT;
33 const int q = CHAR_BIT - 1 - off % CHAR_BIT;
34 if (q == CHAR_BIT - 1) {
35 // Zero next char and write bit
36 wb->bit_buffer[p] = bit << q;
37 } else {
38 wb->bit_buffer[p] &= ~(1 << q);
39 wb->bit_buffer[p] |= bit << q;
40 }
41 wb->bit_offset = off + 1;
42 }
43
overwrite_bit(struct aom_write_bit_buffer * wb,int bit)44 static void overwrite_bit(struct aom_write_bit_buffer *wb, int bit) {
45 // Do not zero bytes but overwrite exisiting values
46 const int off = (int)wb->bit_offset;
47 const int p = off / CHAR_BIT;
48 const int q = CHAR_BIT - 1 - off % CHAR_BIT;
49 wb->bit_buffer[p] &= ~(1 << q);
50 wb->bit_buffer[p] |= bit << q;
51 wb->bit_offset = off + 1;
52 }
53
aom_wb_write_literal(struct aom_write_bit_buffer * wb,int data,int bits)54 void aom_wb_write_literal(struct aom_write_bit_buffer *wb, int data, int bits) {
55 assert(bits <= 31);
56 int bit;
57 for (bit = bits - 1; bit >= 0; bit--) aom_wb_write_bit(wb, (data >> bit) & 1);
58 }
59
aom_wb_write_unsigned_literal(struct aom_write_bit_buffer * wb,uint32_t data,int bits)60 void aom_wb_write_unsigned_literal(struct aom_write_bit_buffer *wb,
61 uint32_t data, int bits) {
62 assert(bits <= 32);
63 int bit;
64 for (bit = bits - 1; bit >= 0; bit--) aom_wb_write_bit(wb, (data >> bit) & 1);
65 }
66
aom_wb_overwrite_literal(struct aom_write_bit_buffer * wb,int data,int bits)67 void aom_wb_overwrite_literal(struct aom_write_bit_buffer *wb, int data,
68 int bits) {
69 int bit;
70 for (bit = bits - 1; bit >= 0; bit--) overwrite_bit(wb, (data >> bit) & 1);
71 }
72
aom_wb_write_inv_signed_literal(struct aom_write_bit_buffer * wb,int data,int bits)73 void aom_wb_write_inv_signed_literal(struct aom_write_bit_buffer *wb, int data,
74 int bits) {
75 aom_wb_write_literal(wb, data, bits + 1);
76 }
77
aom_wb_write_uvlc(struct aom_write_bit_buffer * wb,uint32_t v)78 void aom_wb_write_uvlc(struct aom_write_bit_buffer *wb, uint32_t v) {
79 int64_t shift_val = ++v;
80 int leading_zeroes = 1;
81
82 assert(shift_val > 0);
83
84 while (shift_val >>= 1) leading_zeroes += 2;
85
86 aom_wb_write_literal(wb, 0, leading_zeroes >> 1);
87 aom_wb_write_unsigned_literal(wb, v, (leading_zeroes + 1) >> 1);
88 }
89
wb_write_primitive_quniform(struct aom_write_bit_buffer * wb,uint16_t n,uint16_t v)90 static void wb_write_primitive_quniform(struct aom_write_bit_buffer *wb,
91 uint16_t n, uint16_t v) {
92 if (n <= 1) return;
93 const int l = get_msb(n) + 1;
94 const int m = (1 << l) - n;
95 if (v < m) {
96 aom_wb_write_literal(wb, v, l - 1);
97 } else {
98 aom_wb_write_literal(wb, m + ((v - m) >> 1), l - 1);
99 aom_wb_write_bit(wb, (v - m) & 1);
100 }
101 }
102
wb_write_primitive_subexpfin(struct aom_write_bit_buffer * wb,uint16_t n,uint16_t k,uint16_t v)103 static void wb_write_primitive_subexpfin(struct aom_write_bit_buffer *wb,
104 uint16_t n, uint16_t k, uint16_t v) {
105 int i = 0;
106 int mk = 0;
107 while (1) {
108 int b = (i ? k + i - 1 : k);
109 int a = (1 << b);
110 if (n <= mk + 3 * a) {
111 wb_write_primitive_quniform(wb, n - mk, v - mk);
112 break;
113 } else {
114 int t = (v >= mk + a);
115 aom_wb_write_bit(wb, t);
116 if (t) {
117 i = i + 1;
118 mk += a;
119 } else {
120 aom_wb_write_literal(wb, v - mk, b);
121 break;
122 }
123 }
124 }
125 }
126
wb_write_primitive_refsubexpfin(struct aom_write_bit_buffer * wb,uint16_t n,uint16_t k,uint16_t ref,uint16_t v)127 static void wb_write_primitive_refsubexpfin(struct aom_write_bit_buffer *wb,
128 uint16_t n, uint16_t k,
129 uint16_t ref, uint16_t v) {
130 wb_write_primitive_subexpfin(wb, n, k, recenter_finite_nonneg(n, ref, v));
131 }
132
aom_wb_write_signed_primitive_refsubexpfin(struct aom_write_bit_buffer * wb,uint16_t n,uint16_t k,int16_t ref,int16_t v)133 void aom_wb_write_signed_primitive_refsubexpfin(struct aom_write_bit_buffer *wb,
134 uint16_t n, uint16_t k,
135 int16_t ref, int16_t v) {
136 ref += n - 1;
137 v += n - 1;
138 const uint16_t scaled_n = (n << 1) - 1;
139 wb_write_primitive_refsubexpfin(wb, scaled_n, k, ref, v);
140 }
141