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74 lines
2.5 KiB
C#
74 lines
2.5 KiB
C#
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using Ryujinx.Graphics.Nvdec.Vp9.Common;
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using System;
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using System.Diagnostics;
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namespace Ryujinx.Graphics.Nvdec.Vp9.Dsp
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{
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internal static class Prob
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{
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public const int MaxProb = 255;
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private static byte GetProb(uint num, uint den)
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{
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Debug.Assert(den != 0);
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{
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int p = (int)(((ulong)num * 256 + (den >> 1)) / den);
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// (p > 255) ? 255 : (p < 1) ? 1 : p;
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int clippedProb = p | ((255 - p) >> 23) | (p == 0 ? 1 : 0);
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return (byte)clippedProb;
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}
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}
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/* This function assumes prob1 and prob2 are already within [1,255] range. */
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public static byte WeightedProb(int prob1, int prob2, int factor)
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{
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return (byte)BitUtils.RoundPowerOfTwo(prob1 * (256 - factor) + prob2 * factor, 8);
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}
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// MODE_MV_MAX_UPDATE_FACTOR (128) * count / MODE_MV_COUNT_SAT;
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private static readonly uint[] CountToUpdateFactor = new uint[]
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{
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0, 6, 12, 19, 25, 32, 38, 44, 51, 57, 64,
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70, 76, 83, 89, 96, 102, 108, 115, 121, 128
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};
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private const int ModeMvCountSat = 20;
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public static byte ModeMvMergeProbs(byte preProb, uint ct0, uint ct1)
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{
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uint den = ct0 + ct1;
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if (den == 0)
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{
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return preProb;
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}
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else
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{
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uint count = Math.Min(den, ModeMvCountSat);
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uint factor = CountToUpdateFactor[(int)count];
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byte prob = GetProb(ct0, den);
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return WeightedProb(preProb, prob, (int)factor);
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}
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}
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private static uint TreeMergeProbsImpl(
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uint i,
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sbyte[] tree,
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ReadOnlySpan<byte> preProbs,
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ReadOnlySpan<uint> counts,
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Span<byte> probs)
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{
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int l = tree[i];
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uint leftCount = (l <= 0) ? counts[-l] : TreeMergeProbsImpl((uint)l, tree, preProbs, counts, probs);
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int r = tree[i + 1];
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uint rightCount = (r <= 0) ? counts[-r] : TreeMergeProbsImpl((uint)r, tree, preProbs, counts, probs);
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probs[(int)(i >> 1)] = ModeMvMergeProbs(preProbs[(int)(i >> 1)], leftCount, rightCount);
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return leftCount + rightCount;
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}
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public static void TreeMergeProbs(sbyte[] tree, ReadOnlySpan<byte> preProbs, ReadOnlySpan<uint> counts, Span<byte> probs)
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{
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TreeMergeProbsImpl(0, tree, preProbs, counts, probs);
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}
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}
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}
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