1 | // Copyright 2013 Google Inc. All Rights Reserved. |
2 | // |
3 | // Use of this source code is governed by a BSD-style license |
4 | // that can be found in the COPYING file in the root of the source |
5 | // tree. An additional intellectual property rights grant can be found |
6 | // in the file PATENTS. All contributing project authors may |
7 | // be found in the AUTHORS file in the root of the source tree. |
8 | // ----------------------------------------------------------------------------- |
9 | // |
10 | // Pseudo-random utilities |
11 | // |
12 | // Author: Skal (pascal.massimino@gmail.com) |
13 | |
14 | #include <string.h> |
15 | #include "src/utils/random_utils.h" |
16 | |
17 | //------------------------------------------------------------------------------ |
18 | |
19 | // 31b-range values |
20 | static const uint32_t kRandomTable[VP8_RANDOM_TABLE_SIZE] = { |
21 | 0x0de15230, 0x03b31886, 0x775faccb, 0x1c88626a, 0x68385c55, 0x14b3b828, |
22 | 0x4a85fef8, 0x49ddb84b, 0x64fcf397, 0x5c550289, 0x4a290000, 0x0d7ec1da, |
23 | 0x5940b7ab, 0x5492577d, 0x4e19ca72, 0x38d38c69, 0x0c01ee65, 0x32a1755f, |
24 | 0x5437f652, 0x5abb2c32, 0x0faa57b1, 0x73f533e7, 0x685feeda, 0x7563cce2, |
25 | 0x6e990e83, 0x4730a7ed, 0x4fc0d9c6, 0x496b153c, 0x4f1403fa, 0x541afb0c, |
26 | 0x73990b32, 0x26d7cb1c, 0x6fcc3706, 0x2cbb77d8, 0x75762f2a, 0x6425ccdd, |
27 | 0x24b35461, 0x0a7d8715, 0x220414a8, 0x141ebf67, 0x56b41583, 0x73e502e3, |
28 | 0x44cab16f, 0x28264d42, 0x73baaefb, 0x0a50ebed, 0x1d6ab6fb, 0x0d3ad40b, |
29 | 0x35db3b68, 0x2b081e83, 0x77ce6b95, 0x5181e5f0, 0x78853bbc, 0x009f9494, |
30 | 0x27e5ed3c |
31 | }; |
32 | |
33 | void VP8InitRandom(VP8Random* const rg, float dithering) { |
34 | memcpy(rg->tab_, kRandomTable, sizeof(rg->tab_)); |
35 | rg->index1_ = 0; |
36 | rg->index2_ = 31; |
37 | rg->amp_ = (dithering < 0.0) ? 0 |
38 | : (dithering > 1.0) ? (1 << VP8_RANDOM_DITHER_FIX) |
39 | : (uint32_t)((1 << VP8_RANDOM_DITHER_FIX) * dithering); |
40 | } |
41 | |
42 | //------------------------------------------------------------------------------ |
43 | |
44 | |