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https://chromium.googlesource.com/libyuv/libyuv
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e0615c0e69
BUG=libyuv:701 TEST=LibYUVBaseTest.BenchmarkHammingDistance_C R=wangcheng@google.com Change-Id: I243003b098bea8ef3809298bbec349ed52a43d8c Reviewed-on: https://chromium-review.googlesource.com/499487 Reviewed-by: Cheng Wang <wangcheng@google.com>
89 lines
2.0 KiB
C++
89 lines
2.0 KiB
C++
/*
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* Copyright 2012 The LibYuv Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "libyuv/basic_types.h"
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#include "libyuv/compare_row.h"
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#ifdef __cplusplus
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namespace libyuv {
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extern "C" {
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#endif
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#if ORIGINAL_OPT
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uint32 HammingDistance_C(const uint8* src_a, const uint8* src_b, int count) {
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uint32 diff = 0u;
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int i;
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for (i = 0; i < count; ++i) {
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int x = src_a[i] ^ src_b[i];
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if (x & 1)
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++diff;
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if (x & 2)
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++diff;
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if (x & 4)
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++diff;
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if (x & 8)
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++diff;
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if (x & 16)
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++diff;
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if (x & 32)
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++diff;
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if (x & 64)
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++diff;
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if (x & 128)
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++diff;
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}
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return diff;
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}
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#endif
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// Hakmem method for hamming distance.
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uint32 HammingDistance_C(const uint8* src_a, const uint8* src_b, int count) {
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uint32 diff = 0u;
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int i;
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for (i = 0; i < count - 3; i += 4) {
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uint32 x = *((uint32*)src_a) ^ *((uint32*)src_b);
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uint32 u = x - ((x >> 1) & 0x55555555);
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u = ((u >> 2) & 0x33333333) + (u & 0x33333333);
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diff += ((((u + (u >> 4)) & 0x0f0f0f0f) * 0x01010101) >> 24);
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src_a += 4;
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src_b += 4;
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}
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return diff;
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}
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uint32 SumSquareError_C(const uint8* src_a, const uint8* src_b, int count) {
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uint32 sse = 0u;
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int i;
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for (i = 0; i < count; ++i) {
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int diff = src_a[i] - src_b[i];
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sse += (uint32)(diff * diff);
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}
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return sse;
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}
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// hash seed of 5381 recommended.
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// Internal C version of HashDjb2 with int sized count for efficiency.
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uint32 HashDjb2_C(const uint8* src, int count, uint32 seed) {
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uint32 hash = seed;
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int i;
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for (i = 0; i < count; ++i) {
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hash += (hash << 5) + src[i];
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}
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return hash;
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}
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#ifdef __cplusplus
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} // extern "C"
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} // namespace libyuv
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#endif
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