libvpx: Pull from upstream

source/libvpx/vp8/common/variance_c.c

Index: source/libvpx/vp8/common/variance_c.c
diff --git a/source/libvpx/vp8/common/variance_c.c b/source/libvpx/vp8/common/variance_c.c
index 773b655efc518128e9ac38c71a025f78ef21e842..79d1ca00c1cc319af84fe351424e510954ff8ee1 100644
--- a/source/libvpx/vp8/common/variance_c.c
+++ b/source/libvpx/vp8/common/variance_c.c
@@ -8,43 +8,34 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-
-#include "variance.h"
+#include "./vp8_rtcd.h"
 #include "filter.h"
+#include "variance.h"
 
-
-unsigned int vp8_get_mb_ss_c
-(
-    const short *src_ptr
-)
-{
-    unsigned int i = 0, sum = 0;
-
-    do
-    {
-        sum += (src_ptr[i] * src_ptr[i]);
-        i++;
-    }
-    while (i < 256);
-
-    return sum;
+/* This is a bad idea.
+ * ctz = count trailing zeros */
+static int ctz(int a) {
+  int b = 0;
+  while (a != 1) {
+    a >>= 1;
+    b++;
+  }
+  return b;
 }
 
-
-static void variance(
+static unsigned int variance(
     const unsigned char *src_ptr,
     int  source_stride,
     const unsigned char *ref_ptr,
     int  recon_stride,
     int  w,
     int  h,
-    unsigned int *sse,
-    int *sum)
+    unsigned int *sse)
 {
     int i, j;
-    int diff;
+    int diff, sum;
 
-    *sum = 0;
+    sum = 0;
     *sse = 0;
 
     for (i = 0; i < h; i++)
@@ -52,114 +43,17 @@ static void variance(
         for (j = 0; j < w; j++)
         {
             diff = src_ptr[j] - ref_ptr[j];
-            *sum += diff;
+            sum += diff;
             *sse += diff * diff;
         }
 
         src_ptr += source_stride;
         ref_ptr += recon_stride;
     }
-}
-
-
-unsigned int vp8_variance16x16_c(
-    const unsigned char *src_ptr,
-    int  source_stride,
-    const unsigned char *ref_ptr,
-    int  recon_stride,
-    unsigned int *sse)
-{
-    unsigned int var;
-    int avg;
 
-
-    variance(src_ptr, source_stride, ref_ptr, recon_stride, 16, 16, &var, &avg);
-    *sse = var;
-    return (var - (((unsigned int)avg * avg) >> 8));
+    return (*sse - (((unsigned int)sum * sum) >> (int)((ctz(w) + ctz(h)))));
 }
 
-unsigned int vp8_variance8x16_c(
-    const unsigned char *src_ptr,
-    int  source_stride,
-    const unsigned char *ref_ptr,
-    int  recon_stride,
-    unsigned int *sse)
-{
-    unsigned int var;
-    int avg;
-
-
-    variance(src_ptr, source_stride, ref_ptr, recon_stride, 8, 16, &var, &avg);
-    *sse = var;
-    return (var - (((unsigned int)avg * avg) >> 7));
-}
-
-unsigned int vp8_variance16x8_c(
-    const unsigned char *src_ptr,
-    int  source_stride,
-    const unsigned char *ref_ptr,
-    int  recon_stride,
-    unsigned int *sse)
-{
-    unsigned int var;
-    int avg;
-
-
-    variance(src_ptr, source_stride, ref_ptr, recon_stride, 16, 8, &var, &avg);
-    *sse = var;
-    return (var - (((unsigned int)avg * avg) >> 7));
-}
-
-
-unsigned int vp8_variance8x8_c(
-    const unsigned char *src_ptr,
-    int  source_stride,
-    const unsigned char *ref_ptr,
-    int  recon_stride,
-    unsigned int *sse)
-{
-    unsigned int var;
-    int avg;
-
-
-    variance(src_ptr, source_stride, ref_ptr, recon_stride, 8, 8, &var, &avg);
-    *sse = var;
-    return (var - (((unsigned int)avg * avg) >> 6));
-}
-
-unsigned int vp8_variance4x4_c(
-    const unsigned char *src_ptr,
-    int  source_stride,
-    const unsigned char *ref_ptr,
-    int  recon_stride,
-    unsigned int *sse)
-{
-    unsigned int var;
-    int avg;
-
-
-    variance(src_ptr, source_stride, ref_ptr, recon_stride, 4, 4, &var, &avg);
-    *sse = var;
-    return (var - (((unsigned int)avg * avg) >> 4));
-}
-
-
-unsigned int vp8_mse16x16_c(
-    const unsigned char *src_ptr,
-    int  source_stride,
-    const unsigned char *ref_ptr,
-    int  recon_stride,
-    unsigned int *sse)
-{
-    unsigned int var;
-    int avg;
-
-    variance(src_ptr, source_stride, ref_ptr, recon_stride, 16, 16, &var, &avg);
-    *sse = var;
-    return var;
-}
-
-
 /****************************************************************************
  *
  *  ROUTINE       : filter_block2d_bil_first_pass
@@ -303,7 +197,7 @@ unsigned int vp8_sub_pixel_variance4x4_c
     /* Now filter Verticaly */
     var_filter_block2d_bil_second_pass(FData3, temp2, 4,  4,  4,  4, VFilter);
 
-    return vp8_variance4x4_c(temp2, 4, dst_ptr, dst_pixels_per_line, sse);
+    return variance(temp2, 4, dst_ptr, dst_pixels_per_line, 4, 4, sse);
 }
 
 
@@ -328,7 +222,7 @@ unsigned int vp8_sub_pixel_variance8x8_c
     var_filter_block2d_bil_first_pass(src_ptr, FData3, src_pixels_per_line, 1, 9, 8, HFilter);
     var_filter_block2d_bil_second_pass(FData3, temp2, 8, 8, 8, 8, VFilter);
 
-    return vp8_variance8x8_c(temp2, 8, dst_ptr, dst_pixels_per_line, sse);
+    return variance(temp2, 8, dst_ptr, dst_pixels_per_line, 8, 8, sse);
 }
 
 unsigned int vp8_sub_pixel_variance16x16_c
@@ -352,7 +246,7 @@ unsigned int vp8_sub_pixel_variance16x16_c
     var_filter_block2d_bil_first_pass(src_ptr, FData3, src_pixels_per_line, 1, 17, 16, HFilter);
     var_filter_block2d_bil_second_pass(FData3, temp2, 16, 16, 16, 16, VFilter);
 
-    return vp8_variance16x16_c(temp2, 16, dst_ptr, dst_pixels_per_line, sse);
+    return variance(temp2, 16, dst_ptr, dst_pixels_per_line, 16, 16, sse);
 }
 
 
@@ -428,7 +322,7 @@ unsigned int vp8_sub_pixel_variance16x8_c
     var_filter_block2d_bil_first_pass(src_ptr, FData3, src_pixels_per_line, 1, 9, 16, HFilter);
     var_filter_block2d_bil_second_pass(FData3, temp2, 16, 16, 8, 16, VFilter);
 
-    return vp8_variance16x8_c(temp2, 16, dst_ptr, dst_pixels_per_line, sse);
+    return variance(temp2, 16, dst_ptr, dst_pixels_per_line, 16, 8, sse);
 }
 
 unsigned int vp8_sub_pixel_variance8x16_c
@@ -454,5 +348,5 @@ unsigned int vp8_sub_pixel_variance8x16_c
     var_filter_block2d_bil_first_pass(src_ptr, FData3, src_pixels_per_line, 1, 17, 8, HFilter);
     var_filter_block2d_bil_second_pass(FData3, temp2, 8, 8, 16, 8, VFilter);
 
-    return vp8_variance8x16_c(temp2, 8, dst_ptr, dst_pixels_per_line, sse);
+    return variance(temp2, 8, dst_ptr, dst_pixels_per_line, 8, 16, sse);
 }