[x265] [PATCH 3 of 4] optimize: improvement TComTrQuant::getSigCtxInc, avoid shift by mask

[Min Chen]

# HG changeset patch
# User Min Chen <chenm003 at 163.com>
# Date 1394845778 25200
# Node ID ce3fd6c2e7958975cd4286f9035182eba7726869
# Parent  626df01b607061744e1e8301e2de9c5c2ba62cb6
optimize: improvement TComTrQuant::getSigCtxInc, avoid shift by mask

diff -r 626df01b6070 -r ce3fd6c2e795 source/Lib/TLibCommon/TComTrQuant.cpp
--- a/source/Lib/TLibCommon/TComTrQuant.cpp	Fri Mar 14 18:09:22 2014 -0700
+++ b/source/Lib/TLibCommon/TComTrQuant.cpp	Fri Mar 14 18:09:38 2014 -0700
@@ -638,7 +638,7 @@
                 }
                 else
                 {
-                    uint16_t ctxSig = getSigCtxInc(patternSigCtx, codingParameters, blkPos);
+                    uint16_t ctxSig = getSigCtxInc(patternSigCtx, log2TrSize, trSize, blkPos, codingParameters);
                     level           = xGetCodedLevel(costCoeff[scanPos], costCoeff0[scanPos], costSig[scanPos],
                                                      levelDouble, maxAbsLevel, baseLevel, ctxSig, oneCtx, absCtx, goRiceParam,
                                                      c1c2Idx, qbits, scaleFactor, 0);
@@ -1014,7 +1014,7 @@
  * \param height height of the block
  * \returns pattern for current coefficient group
  */
-int TComTrQuant::calcPatternSigCtx(const uint64_t sigCoeffGroupFlag64, uint32_t cgPosX, uint32_t cgPosY, uint32_t log2TrSizeCG)
+uint32_t TComTrQuant::calcPatternSigCtx(const uint64_t sigCoeffGroupFlag64, uint32_t cgPosX, uint32_t cgPosY, uint32_t log2TrSizeCG)
 {
     if (log2TrSizeCG == 0) return 0;
 
@@ -1037,11 +1037,13 @@
  * \param textureType texture type (TEXT_LUMA...)
  * \returns ctxInc for current scan position
  */
-int TComTrQuant::getSigCtxInc(int                              patternSigCtx,
-                              const TUEntropyCodingParameters &codingParameters,
-                              const int                        blkPos)
+uint32_t TComTrQuant::getSigCtxInc(const uint32_t                   patternSigCtx,
+                                   const uint32_t                   log2TrSize,
+                                   const uint32_t                   trSize,
+                                   const uint32_t                   blkPos,
+                                   const TUEntropyCodingParameters &codingParameters)
 {
-    static const int ctxIndMap[16] =
+    static const uint8_t ctxIndMap[16] =
     {
         0, 1, 4, 5,
         2, 3, 4, 5,
@@ -1051,16 +1053,17 @@
 
     if (blkPos == 0) return 0; //special case for the DC context variable
 
-    const int log2TrSize = codingParameters.log2TrSize;
     if (log2TrSize == 2) //4x4
     {
         return ctxIndMap[blkPos];
     }
 
     const uint32_t posY           = blkPos >> log2TrSize;
-    const uint32_t posX           = blkPos - (posY << log2TrSize);
+    const uint32_t posX           = blkPos & (trSize - 1);
+    assert((blkPos - (posY << log2TrSize)) == posX);
 
-    int posXinSubset = posX & 3;
+    int posXinSubset = blkPos & 3;
+    assert((posX & 3) == (blkPos & 3));
     int posYinSubset = posY & 3;
 
     // NOTE: [patternSigCtx][posXinSubset][posYinSubset]
diff -r 626df01b6070 -r ce3fd6c2e795 source/Lib/TLibCommon/TComTrQuant.h
--- a/source/Lib/TLibCommon/TComTrQuant.h	Fri Mar 14 18:09:22 2014 -0700
+++ b/source/Lib/TLibCommon/TComTrQuant.h	Fri Mar 14 18:09:38 2014 -0700
@@ -158,8 +158,8 @@
     void setScalingList(TComScalingList *scalingList);
     void processScalingListEnc(int32_t *coeff, int32_t *quantcoeff, int quantScales, uint32_t height, uint32_t width, uint32_t ratio, int sizuNum, uint32_t dc);
     void processScalingListDec(int32_t *coeff, int32_t *dequantcoeff, int invQuantScales, uint32_t height, uint32_t width, uint32_t ratio, int sizuNum, uint32_t dc);
-    static int calcPatternSigCtx(const uint64_t sigCoeffGroupFlag64, uint32_t cgPosX, uint32_t cgPosY, uint32_t log2TrSizeCG);
-    static int getSigCtxInc(int patternSigCtx, const TUEntropyCodingParameters &codingParameters, const int blkPos);
+    static uint32_t calcPatternSigCtx(const uint64_t sigCoeffGroupFlag64, uint32_t cgPosX, uint32_t cgPosY, uint32_t log2TrSizeCG);
+    static uint32_t getSigCtxInc(uint32_t patternSigCtx, const uint32_t log2TrSize, const uint32_t trSize, const uint32_t blkPos, const TUEntropyCodingParameters &codingParameters);
     static uint32_t getSigCoeffGroupCtxInc(const uint64_t sigCoeffGroupFlag64, uint32_t cgPosX, uint32_t cgPosY, const uint32_t log2TrSizeCG);
     static void getTUEntropyCodingParameters(TComDataCU* cu, TUEntropyCodingParameters &result, uint32_t absPartIdx, uint32_t log2TrSize, TextType ttype);
     estBitsSbacStruct* m_estBitsSbac;
diff -r 626df01b6070 -r ce3fd6c2e795 source/Lib/TLibEncoder/TEncSbac.cpp
--- a/source/Lib/TLibEncoder/TEncSbac.cpp	Fri Mar 14 18:09:22 2014 -0700
+++ b/source/Lib/TLibEncoder/TEncSbac.cpp	Fri Mar 14 18:09:38 2014 -0700
@@ -2166,7 +2166,7 @@
                 sig     = (coeff[blkPos] != 0);
                 if (scanPosSig > subPos || subSet == 0 || numNonZero)
                 {
-                    ctxSig  = TComTrQuant::getSigCtxInc(patternSigCtx, codingParameters, blkPos);
+                    ctxSig  = TComTrQuant::getSigCtxInc(patternSigCtx, log2TrSize, trSize, blkPos, codingParameters);
                     m_binIf->encodeBin(sig, baseCtx[ctxSig]);
                 }
                 if (sig)