text: /*
   *  Copyright (c) 2013 The WebRTC 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 "webrtc/modules/desktop_capture/differ_block.h"
  
  #include <string.h>
  
  #include "webrtc/typedefs.h"
  #include "webrtc/modules/desktop_capture/differ_block_sse2.h"
  #include "webrtc/system_wrappers/include/cpu_features_wrapper.h"
  
  namespace webrtc {
  
  bool BlockDifference_C(const uint8_t* image1,
                         const uint8_t* image2,
                         int stride) {
    int width_bytes = kBlockSize * kBytesPerPixel;
  
    for (int y = 0; y < kBlockSize; y++) {
      if (memcmp(image1, image2, width_bytes) != 0)
        return true;
      image1 += stride;
      image2 += stride;
    }
    return false;
  }
  
  bool BlockDifference(const uint8_t* image1,
                       const uint8_t* image2,
                       int stride) {
    static bool (*diff_proc)(const uint8_t*, const uint8_t*, int) = NULL;
  
    if (!diff_proc) {
  #if defined(WEBRTC_ARCH_ARM_FAMILY) || defined(WEBRTC_ARCH_MIPS_FAMILY)
      // For ARM and MIPS processors, always use C version.
      // TODO(hclam): Implement a NEON version.
      diff_proc = &BlockDifference_C;
  #else
      bool have_sse2 = WebRtc_GetCPUInfo(kSSE2) != 0;
      // For x86 processors, check if SSE2 is supported.
      if (have_sse2 && kBlockSize == 32) {
        diff_proc = &BlockDifference_SSE2_W32;
      } else if (have_sse2 && kBlockSize == 16) {
        diff_proc = &BlockDifference_SSE2_W16;
      } else {
        diff_proc = &BlockDifference_C;
      }
  #endif
    }
  
    return diff_proc(image1, image2, stride);
  }
  
  }  // namespace webrtc
  