1 /*
2 * Copyright 2020 The libgav1 Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #ifndef LIBGAV1_SRC_DSP_FILM_GRAIN_COMMON_H_
18 #define LIBGAV1_SRC_DSP_FILM_GRAIN_COMMON_H_
19
20 #include <cstdint>
21
22 namespace libgav1 {
23
24 template <int bitdepth>
GetGrainMax()25 int GetGrainMax() {
26 return (1 << (bitdepth - 1)) - 1;
27 }
28
29 template <int bitdepth>
GetGrainMin()30 int GetGrainMin() {
31 return -(1 << (bitdepth - 1));
32 }
33
GetFilmGrainRandomNumber(int bits,uint16_t * seed)34 inline int GetFilmGrainRandomNumber(int bits, uint16_t* seed) {
35 uint16_t s = *seed;
36 uint16_t bit = (s ^ (s >> 1) ^ (s >> 3) ^ (s >> 12)) & 1;
37 s = (s >> 1) | (bit << 15);
38 *seed = s;
39 return s >> (16 - bits);
40 }
41
42 enum {
43 kAutoRegressionBorder = 3,
44 // The width of the luma noise array.
45 kLumaWidth = 82,
46 // The height of the luma noise array.
47 kLumaHeight = 73,
48 // The two possible widths of the chroma noise array.
49 kMinChromaWidth = 44,
50 kMaxChromaWidth = 82,
51 // The two possible heights of the chroma noise array.
52 kMinChromaHeight = 38,
53 kMaxChromaHeight = 73,
54 // The standard scaling lookup table maps bytes to bytes, so only uses 256
55 // elements, plus one for overflow in 12bpp lookups. The size is scaled up for
56 // 10bpp.
57 kScalingLookupTableSize = 257,
58 // Padding is added to the scaling lookup table to permit overwrites by
59 // InitializeScalingLookupTable_NEON.
60 kScalingLookupTablePadding = 6,
61 // Padding is added to each row of the noise image to permit overreads by
62 // BlendNoiseWithImageLuma_NEON and overwrites by WriteOverlapLine8bpp_NEON.
63 kNoiseImagePadding = 15,
64 // Padding is added to the end of the |noise_stripes_| buffer to permit
65 // overreads by WriteOverlapLine8bpp_NEON.
66 kNoiseStripePadding = 7,
67 }; // anonymous enum
68
69 } // namespace libgav1
70
71 #endif // LIBGAV1_SRC_DSP_FILM_GRAIN_COMMON_H_
72