/src/aom/aom_dsp/binary_codes_writer.c
Line | Count | Source (jump to first uncovered line) |
1 | | /* |
2 | | * Copyright (c) 2017, 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 "aom_dsp/bitwriter.h" |
13 | | #include "aom_dsp/binary_codes_writer.h" |
14 | | #include "aom_dsp/recenter.h" |
15 | | #include "aom_ports/bitops.h" |
16 | | |
17 | | // Encodes a value v in [0, n-1] quasi-uniformly |
18 | 0 | static void write_primitive_quniform(aom_writer *w, uint16_t n, uint16_t v) { |
19 | 0 | if (n <= 1) return; |
20 | 0 | const int l = get_msb(n) + 1; |
21 | 0 | const int m = (1 << l) - n; |
22 | 0 | if (v < m) { |
23 | 0 | aom_write_literal(w, v, l - 1); |
24 | 0 | } else { |
25 | 0 | aom_write_literal(w, m + ((v - m) >> 1), l - 1); |
26 | 0 | aom_write_bit(w, (v - m) & 1); |
27 | 0 | } |
28 | 0 | } |
29 | | |
30 | 0 | static int count_primitive_quniform(uint16_t n, uint16_t v) { |
31 | 0 | if (n <= 1) return 0; |
32 | 0 | const int l = get_msb(n) + 1; |
33 | 0 | const int m = (1 << l) - n; |
34 | 0 | return v < m ? l - 1 : l; |
35 | 0 | } |
36 | | |
37 | | // Finite subexponential code that codes a symbol v in [0, n-1] with parameter k |
38 | | static void write_primitive_subexpfin(aom_writer *w, uint16_t n, uint16_t k, |
39 | 0 | uint16_t v) { |
40 | 0 | int i = 0; |
41 | 0 | int mk = 0; |
42 | 0 | while (1) { |
43 | 0 | int b = (i ? k + i - 1 : k); |
44 | 0 | int a = (1 << b); |
45 | 0 | if (n <= mk + 3 * a) { |
46 | 0 | write_primitive_quniform(w, n - mk, v - mk); |
47 | 0 | break; |
48 | 0 | } else { |
49 | 0 | int t = (v >= mk + a); |
50 | 0 | aom_write_bit(w, t); |
51 | 0 | if (t) { |
52 | 0 | i = i + 1; |
53 | 0 | mk += a; |
54 | 0 | } else { |
55 | 0 | aom_write_literal(w, v - mk, b); |
56 | 0 | break; |
57 | 0 | } |
58 | 0 | } |
59 | 0 | } |
60 | 0 | } |
61 | | |
62 | 0 | static int count_primitive_subexpfin(uint16_t n, uint16_t k, uint16_t v) { |
63 | 0 | int count = 0; |
64 | 0 | int i = 0; |
65 | 0 | int mk = 0; |
66 | 0 | while (1) { |
67 | 0 | int b = (i ? k + i - 1 : k); |
68 | 0 | int a = (1 << b); |
69 | 0 | if (n <= mk + 3 * a) { |
70 | 0 | count += count_primitive_quniform(n - mk, v - mk); |
71 | 0 | break; |
72 | 0 | } else { |
73 | 0 | int t = (v >= mk + a); |
74 | 0 | count++; |
75 | 0 | if (t) { |
76 | 0 | i = i + 1; |
77 | 0 | mk += a; |
78 | 0 | } else { |
79 | 0 | count += b; |
80 | 0 | break; |
81 | 0 | } |
82 | 0 | } |
83 | 0 | } |
84 | 0 | return count; |
85 | 0 | } |
86 | | |
87 | | // Finite subexponential code that codes a symbol v in [0, n-1] with parameter k |
88 | | // based on a reference ref also in [0, n-1]. |
89 | | // Recenters symbol around r first and then uses a finite subexponential code. |
90 | | void aom_write_primitive_refsubexpfin(aom_writer *w, uint16_t n, uint16_t k, |
91 | 0 | uint16_t ref, uint16_t v) { |
92 | 0 | write_primitive_subexpfin(w, n, k, recenter_finite_nonneg(n, ref, v)); |
93 | 0 | } |
94 | | |
95 | | int aom_count_primitive_refsubexpfin(uint16_t n, uint16_t k, uint16_t ref, |
96 | 0 | uint16_t v) { |
97 | 0 | return count_primitive_subexpfin(n, k, recenter_finite_nonneg(n, ref, v)); |
98 | 0 | } |
99 | | |
100 | | int aom_count_signed_primitive_refsubexpfin(uint16_t n, uint16_t k, int16_t ref, |
101 | 0 | int16_t v) { |
102 | 0 | ref += n - 1; |
103 | 0 | v += n - 1; |
104 | 0 | const uint16_t scaled_n = (n << 1) - 1; |
105 | 0 | return aom_count_primitive_refsubexpfin(scaled_n, k, ref, v); |
106 | 0 | } |