[x265] [PATCH 1 of 3] improve codeCoeffNxN by inline getSigCtxInc()

[Steve Borho]

On 03/24, Min Chen wrote:
> # HG changeset patch
> # User Min Chen <chenm003 at 163.com>
> # Date 1427247531 25200
> # Node ID 51f63f5968617c7854b30d4e339418802e383795
> # Parent  e637273e2ae6391d43a037d9a4298a8be8e178ad
> improve codeCoeffNxN by inline getSigCtxInc()

queued the series for testing

> ---
>  source/encoder/entropy.cpp |  102 +++++++++++++++++++++++++++++++++++++++-----
>  1 files changed, 91 insertions(+), 11 deletions(-)
> 
> diff -r e637273e2ae6 -r 51f63f596861 source/encoder/entropy.cpp
> --- a/source/encoder/entropy.cpp	Tue Mar 24 15:31:05 2015 -0500
> +++ b/source/encoder/entropy.cpp	Tue Mar 24 18:38:51 2015 -0700
> @@ -1555,21 +1555,101 @@
>          // encode significant_coeff_flag
>          if (sigCoeffGroupFlag64 & cgBlkPosMask)
>          {
> +            X265_CHECK((log2TrSize != 2) || (log2TrSize == 2 && subSet == 0), "log2TrSize and subSet mistake!\n");
>              const int patternSigCtx = Quant::calcPatternSigCtx(sigCoeffGroupFlag64, cgPosX, cgPosY, codingParameters.log2TrSizeCG);
> -            uint32_t blkPos, sig, ctxSig;
> -            for (; scanPosSigOff >= 0; scanPosSigOff--)
> +
> +            if (log2TrSize == 2)
>              {
> -                blkPos  = codingParameters.scan[subPosBase + scanPosSigOff];
> -                sig     = scanFlagMask & 1;
> -                scanFlagMask >>= 1;
> -                X265_CHECK((uint32_t)(coeff[blkPos] != 0) == sig, "sign bit mistake\n");
> -                if (scanPosSigOff != 0 || subSet == 0 || numNonZero)
> +                uint32_t blkPos, sig, ctxSig;
> +                for (; scanPosSigOff >= 0; scanPosSigOff--)
>                  {
> -                    ctxSig = Quant::getSigCtxInc(patternSigCtx, log2TrSize, trSize, blkPos, bIsLuma, codingParameters.firstSignificanceMapContext);
> -                    encodeBin(sig, baseCtx[ctxSig]);
> +                    blkPos  = codingParameters.scan[subPosBase + scanPosSigOff];
> +                    sig     = scanFlagMask & 1;
> +                    scanFlagMask >>= 1;
> +                    X265_CHECK((uint32_t)(coeff[blkPos] != 0) == sig, "sign bit mistake\n");
> +                    {
> +                        static const uint8_t ctxIndMap[16] =
> +                        {
> +                            0, 1, 4, 5,
> +                            2, 3, 4, 5,
> +                            6, 6, 8, 8,
> +                            7, 7, 8, 8
> +                        };
> +                        ctxSig = ctxIndMap[blkPos];
> +                        X265_CHECK(ctxSig == Quant::getSigCtxInc(patternSigCtx, log2TrSize, trSize, blkPos, bIsLuma, codingParameters.firstSignificanceMapContext), "sigCtx mistake!\n");;
> +                        encodeBin(sig, baseCtx[ctxSig]);
> +                    }
> +                    absCoeff[numNonZero] = int(abs(coeff[blkPos]));
> +                    numNonZero += sig;
>                  }
> -                absCoeff[numNonZero] = int(abs(coeff[blkPos]));
> -                numNonZero += sig;
> +            }
> +            else
> +            {
> +                X265_CHECK((log2TrSize > 2), "log2TrSize must be more than 2 in this path!\n");
> +
> +                // NOTE: [patternSigCtx][posXinSubset][posYinSubset]
> +                static const uint8_t table_cnt[4][4][4] =
> +                {
> +                    // patternSigCtx = 0
> +                    {
> +                        { 2, 1, 1, 0 },
> +                        { 1, 1, 0, 0 },
> +                        { 1, 0, 0, 0 },
> +                        { 0, 0, 0, 0 },
> +                    },
> +                    // patternSigCtx = 1
> +                    {
> +                        { 2, 1, 0, 0 },
> +                        { 2, 1, 0, 0 },
> +                        { 2, 1, 0, 0 },
> +                        { 2, 1, 0, 0 },
> +                    },
> +                    // patternSigCtx = 2
> +                    {
> +                        { 2, 2, 2, 2 },
> +                        { 1, 1, 1, 1 },
> +                        { 0, 0, 0, 0 },
> +                        { 0, 0, 0, 0 },
> +                    },
> +                    // patternSigCtx = 3
> +                    {
> +                        { 2, 2, 2, 2 },
> +                        { 2, 2, 2, 2 },
> +                        { 2, 2, 2, 2 },
> +                        { 2, 2, 2, 2 },
> +                    }
> +                };
> +                const uint8_t (*tabSigCtx)[4] = table_cnt[(uint32_t)patternSigCtx];
> +                const int offset = codingParameters.firstSignificanceMapContext;
> +                const uint32_t lumaMask = bIsLuma ? ~0 : 0;
> +                static const uint32_t posXY4Mask[] = {0x024, 0x0CC, 0x39C};
> +                const uint32_t posGT4Mask = posXY4Mask[log2TrSize - 3] & lumaMask;
> +
> +                uint32_t blkPos, sig, ctxSig;
> +                for (; scanPosSigOff >= 0; scanPosSigOff--)
> +                {
> +                    blkPos  = codingParameters.scan[subPosBase + scanPosSigOff];
> +                    X265_CHECK(blkPos || (subPosBase + scanPosSigOff == 0), "blkPos==0 must be at scan[0]\n");
> +                    const uint32_t posZeroMask = (subPosBase + scanPosSigOff) ? ~0 : 0;
> +                    sig     = scanFlagMask & 1;
> +                    scanFlagMask >>= 1;
> +                    X265_CHECK((uint32_t)(coeff[blkPos] != 0) == sig, "sign bit mistake\n");
> +                    if (scanPosSigOff != 0 || subSet == 0 || numNonZero)
> +                    {
> +                        const uint32_t posY = blkPos >> log2TrSize;
> +                        const uint32_t posOffset = (blkPos & posGT4Mask) ? 3 : 0;
> +
> +                        const uint32_t posXinSubset = blkPos & 3;
> +                        const uint32_t posYinSubset = posY & 3;
> +                        const uint32_t cnt = tabSigCtx[posXinSubset][posYinSubset] + offset;
> +                        ctxSig = (cnt + posOffset) & posZeroMask;
> +
> +                        X265_CHECK(ctxSig == Quant::getSigCtxInc(patternSigCtx, log2TrSize, trSize, blkPos, bIsLuma, codingParameters.firstSignificanceMapContext), "sigCtx mistake!\n");;
> +                        encodeBin(sig, baseCtx[ctxSig]);
> +                    }
> +                    absCoeff[numNonZero] = int(abs(coeff[blkPos]));
> +                    numNonZero += sig;
> +                }
>              }
>          }
>          X265_CHECK(coeffNum[subSet] == numNonZero, "coefNum mistake\n");
> 
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-- 
Steve Borho