initial commit

pjproject-2.11.1/third_party/yuv/source/compare_common.cc

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+/*
+ *  Copyright 2012 The LibYuv Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS. All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "libyuv/basic_types.h"
+
+#include "libyuv/compare_row.h"
+
+#ifdef __cplusplus
+namespace libyuv {
+extern "C" {
+#endif
+
+#if ORIGINAL_OPT
+uint32 HammingDistance_C1(const uint8* src_a, const uint8* src_b, int count) {
+  uint32 diff = 0u;
+
+  int i;
+  for (i = 0; i < count; ++i) {
+    int x = src_a[i] ^ src_b[i];
+    if (x & 1)
+      ++diff;
+    if (x & 2)
+      ++diff;
+    if (x & 4)
+      ++diff;
+    if (x & 8)
+      ++diff;
+    if (x & 16)
+      ++diff;
+    if (x & 32)
+      ++diff;
+    if (x & 64)
+      ++diff;
+    if (x & 128)
+      ++diff;
+  }
+  return diff;
+}
+#endif
+
+// Hakmem method for hamming distance.
+uint32 HammingDistance_C(const uint8* src_a, const uint8* src_b, int count) {
+  uint32 diff = 0u;
+
+  int i;
+  for (i = 0; i < count - 3; i += 4) {
+    uint32 x = *((uint32*)src_a) ^ *((uint32*)src_b);
+    uint32 u = x - ((x >> 1) & 0x55555555);
+    u = ((u >> 2) & 0x33333333) + (u & 0x33333333);
+    diff += ((((u + (u >> 4)) & 0x0f0f0f0f) * 0x01010101) >> 24);
+    src_a += 4;
+    src_b += 4;
+  }
+
+  for (; i < count; ++i) {
+    uint32 x = *src_a ^ *src_b;
+    uint32 u = x - ((x >> 1) & 0x55);
+    u = ((u >> 2) & 0x33) + (u & 0x33);
+    diff += (u + (u >> 4)) & 0x0f;
+    src_a += 1;
+    src_b += 1;
+  }
+
+  return diff;
+}
+
+uint32 SumSquareError_C(const uint8* src_a, const uint8* src_b, int count) {
+  uint32 sse = 0u;
+  int i;
+  for (i = 0; i < count; ++i) {
+    int diff = src_a[i] - src_b[i];
+    sse += (uint32)(diff * diff);
+  }
+  return sse;
+}
+
+// hash seed of 5381 recommended.
+// Internal C version of HashDjb2 with int sized count for efficiency.
+uint32 HashDjb2_C(const uint8* src, int count, uint32 seed) {
+  uint32 hash = seed;
+  int i;
+  for (i = 0; i < count; ++i) {
+    hash += (hash << 5) + src[i];
+  }
+  return hash;
+}
+
+#ifdef __cplusplus
+}  // extern "C"
+}  // namespace libyuv
+#endif