[x265] [PATCH] A few small performance improvements for intrapred c code

[dtyx265 at gmail.com]

# HG changeset patch
# User David T Yuen <dtyx265 at gmail.com>
# Date 1412127675 25200
# Node ID 353ccf9c2b2adc37cfb1bc7124fcca131599e0ad
# Parent  5a6845566d1492d29af29ecc0cf75d644994735c
A few small performance improvements for intrapred c code

diff -r 5a6845566d14 -r 353ccf9c2b2a source/common/intrapred.cpp
--- a/source/common/intrapred.cpp	Mon Sep 29 17:37:47 2014 -0500
+++ b/source/common/intrapred.cpp	Tue Sep 30 18:41:15 2014 -0700
@@ -35,10 +35,6 @@
     for (w = 0; w < width; w++)
     {
         sum += above[w];
-    }
-
-    for (w = 0; w < width; w++)
-    {
         sum += left[w];
     }
 
@@ -57,11 +53,10 @@
         dst[x] = (pixel)((above[x] +  3 * dst[x] + 2) >> 2);
     }
 
-    dst += dststride;
     for (int y = 1; y < size; y++)
     {
+        dst += dststride;
         *dst = (pixel)((left[y] + 3 * *dst + 2) >> 2);
-        dst += dststride;
     }
 }
 
@@ -134,13 +129,11 @@
 }
 
 template<int width>
-void intra_pred_ang_c(pixel* dst, intptr_t dstStride, pixel *refLeft, pixel *refAbove, int dirMode, int bFilter)
+void intra_pred_ang_c1(pixel* dst, intptr_t dstStride, pixel *refLeft, pixel *refAbove, int dirMode, int bFilter)
 {
     // Map the mode index to main prediction direction and angle
     int k, l;
-    bool modeHor       = (dirMode < 18);
-    bool modeVer       = !modeHor;
-    int intraPredAngle = modeVer ? (int)dirMode - VER_IDX : modeHor ? -((int)dirMode - HOR_IDX) : 0;
+    int intraPredAngle = dirMode > 17 ? (int)dirMode - VER_IDX : -((int)dirMode - HOR_IDX);
     int absAng         = abs(intraPredAngle);
     int signAng        = intraPredAngle < 0 ? -1 : 1;
 
@@ -154,27 +147,12 @@
 
     // Do angular predictions
     {
-        pixel* refMain;
-        pixel* refSide;
-
-        // Initialise the Main and Left reference array.
-        if (intraPredAngle < 0)
+        pixel* refMain = refLeft;
+        pixel* refSide = refAbove;
+        if (dirMode > 17)
         {
-            refMain = (modeVer ? refAbove : refLeft); // + (width - 1);
-            refSide = (modeVer ? refLeft : refAbove); // + (width - 1);
-
-            // Extend the Main reference to the left.
-            int invAngleSum    = 128; // rounding for (shift by 8)
-            for (k = -1; k > width * intraPredAngle >> 5; k--)
-            {
-                invAngleSum += invAngle;
-                refMain[k] = refSide[invAngleSum >> 8];
-            }
-        }
-        else
-        {
-            refMain = modeVer ? refAbove : refLeft;
-            refSide = modeVer ? refLeft  : refAbove;
+            refMain = refAbove;
+            refSide = refLeft;
         }
 
         if (intraPredAngle == 0)
@@ -197,6 +175,18 @@
         }
         else
         {
+            // Initialise the Main and Left reference array.
+            if (intraPredAngle < 0)
+            {
+            // Extend the Main reference to the left.
+                int invAngleSum    = 128; // rounding for (shift by 8)
+                for (k = -1; k > width * intraPredAngle >> 5; k--)
+                {
+                    invAngleSum += invAngle;
+                    refMain[k] = refSide[invAngleSum >> 8];
+                }
+            }
+
             int deltaPos = 0;
             int deltaInt;
             int deltaFract;
@@ -227,18 +217,24 @@
                 }
             }
         }
+    }
+}
 
-        // Flip the block if this is the horizontal mode
-        if (modeHor)
+template<int width>
+void intra_pred_ang_c(pixel* dst, intptr_t dstStride, pixel *refLeft, pixel *refAbove, int dirMode, int bFilter)
+{
+    int k, l;
+    intra_pred_ang_c1<width>(dst, dstStride, refLeft, refAbove, dirMode, bFilter);
+
+    if (dirMode < 18)
+    {
+        for (k = 0; k < width - 1; k++)
         {
-            for (k = 0; k < width - 1; k++)
+            for (l = k + 1; l < width; l++)
             {
-                for (l = k + 1; l < width; l++)
-                {
-                    pixel tmp              = dst[k * dstStride + l];
-                    dst[k * dstStride + l] = dst[l * dstStride + k];
-                    dst[l * dstStride + k] = tmp;
-                }
+                dst[l * dstStride + k] ^= dst[k * dstStride + l];
+                dst[k * dstStride + l] ^= dst[l * dstStride + k];
+                dst[l * dstStride + k] ^= dst[k * dstStride + l];
             }
         }
     }
@@ -250,28 +246,22 @@
     const int size = 1 << log2Size;
     for (int mode = 2; mode <= 34; mode++)
     {
-        pixel *left  = (g_intraFilterFlags[mode] & size ? left1  : left0);
-        pixel *above = (g_intraFilterFlags[mode] & size ? above1 : above0);
+        pixel *left;
+        pixel *above;
+
+        if (g_intraFilterFlags[mode] & size)
+        {
+            left = left1;
+            above = above1;
+        }
+        else
+        {
+            left = left0;
+            above = above0;
+        }
         pixel *out = dest + ((mode - 2) << (log2Size * 2));
 
-        intra_pred_ang_c<size>(out, size, left, above, mode, bLuma);
-
-        // Optimize code don't flip buffer
-        bool modeHor = (mode < 18);
-
-        // transpose the block if this is a horizontal mode
-        if (modeHor)
-        {
-            for (int k = 0; k < size - 1; k++)
-            {
-                for (int l = k + 1; l < size; l++)
-                {
-                    pixel tmp         = out[k * size + l];
-                    out[k * size + l] = out[l * size + k];
-                    out[l * size + k] = tmp;
-                }
-            }
-        }
+        intra_pred_ang_c1<size>(out, size, left, above, mode, bLuma);
     }
 }
 }