1 files changed, 33 insertions, 15 deletions
diff --git a/remoting/host/differ_block.cc b/remoting/host/differ_block.cc
index 4dfe58c..f7b785d 100644
--- a/remoting/host/differ_block.cc
+++ b/remoting/host/differ_block.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "differ_block.h"
+#include "remoting/host/differ_block.h"
 
 #include <stdlib.h>
 
@@ -20,11 +20,6 @@
 
 namespace remoting {
 
-// TODO(fbarchard): Use common header for block size.
-const int kBlockWidth = 32;
-const int kBlockHeight = 32;
-const int kBytesPerPixel = 3;
-
 #if USE_SSE2
 int BlockDifference(const uint8* image1, const uint8* image2, int stride) {
   __m128i acc = _mm_setzero_si128();
@@ -58,25 +53,48 @@ int BlockDifference(const uint8* image1, const uint8* image2, int stride) {
     v1 = _mm_loadu_si128(i2 + 5);
     sad = _mm_sad_epu8(v0, v1);
     acc = _mm_adds_epu16(acc, sad);
+    v0 = _mm_loadu_si128(i1 + 6);
+    v1 = _mm_loadu_si128(i2 + 6);
+    sad = _mm_sad_epu8(v0, v1);
+    acc = _mm_adds_epu16(acc, sad);
+    v0 = _mm_loadu_si128(i1 + 7);
+    v1 = _mm_loadu_si128(i2 + 7);
+    sad = _mm_sad_epu8(v0, v1);
+    acc = _mm_adds_epu16(acc, sad);
+    sad = _mm_shuffle_epi32(acc, 0xEE);  // [acc3, acc2, acc3, acc2]
+    sad = _mm_adds_epu16(sad, acc);
+    int diff = _mm_cvtsi128_si32(sad);
+    if (diff) {
+      return 1;
+    }
     image1 += stride;
     image2 += stride;
   }
-  sad = _mm_shuffle_epi32(acc, 0xEE); // [acc3, acc2, acc3, acc2]
-  sad = _mm_adds_epu16(sad, acc);
-  int diff = _mm_cvtsi128_si32(sad);
-  return diff;
+  return 0;
 }
 #else
 int BlockDifference(const uint8* image1, const uint8* image2, int stride) {
-  int diff = 0;
-  for (int y = 0; y < kBlockHeight; ++y) {
-    for (int x = 0; x < kBlockWidth * kBytesPerPixel; ++x) {
-      diff += abs(image1[x] - image2[x]);
+  // Number of uint64s in each row of the block.
+  // This must be an integral number.
+  int int64s_per_row = (kBlockWidth * kBytesPerPixel) / sizeof(uint64);
+
+  for (int y = 0; y < kBlockHeight; y++) {
+    const uint64* prev = reinterpret_cast<const uint64*>(image1);
+    const uint64* curr = reinterpret_cast<const uint64*>(image2);
+
+    // Check each row in uint64-sized chunks.
+    // Note that this check may straddle multiple pixels. This is OK because
+    // we're interested in identifying whether or not there was change - we
+    // don't care what the actual change is.
+    for (int x = 0; x < int64s_per_row; x++) {
+      if (*prev++ != *curr++) {
+        return 1;
+      }
     }
     image1 += stride;
     image2 += stride;
   }
-  return diff;
+  return 0;
 }
 #endif