mmx for linux yuv convert function....

media/base/yuv_row.h

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // yuv_row internal functions to handle YUV conversion and scaling to RGB.
 // These functions are used from both yuv_convert.cc and yuv_scale.cc.
 
+// TODO(fbarchard): Write function that can handle rotation and scaling.
+
 #ifndef MEDIA_BASE_YUV_ROW_H_
 #define MEDIA_BASE_YUV_ROW_H_
 
 #include "base/basictypes.h"
 
-namespace media {
-
+extern "C" {
 // Can only do 1x.
 // This is the second fastest of the scalers.
 void FastConvertYUVToRGB32Row(const uint8* y_buf,
                               const uint8* u_buf,
                               const uint8* v_buf,
                               uint8* rgb_buf,
                               int width);
 
 // Can do 1x, half size or any scale down by an integer amount.
 // Step can be negative (mirroring, rotate 180).
@@ skipping 27 matching lines @@
 // Handles arbitrary scaling up or down.
 // Mirroring is supported, but not 90 or 270 degree rotation.
 // Chroma is under sampled every 2 pixels for performance.
 // This is the slowest of the scalers.
 void ScaleYUVToRGB32Row(const uint8* y_buf,
                         const uint8* u_buf,
                         const uint8* v_buf,
                         uint8* rgb_buf,
                         int width,
                         int scaled_dx);
+}  // extern "C"
 
-// MMX for Windows; C++ for other platforms.
-#ifndef USE_MMX
+#if !defined(USE_MMX)
 #if defined(_MSC_VER)
 #define USE_MMX 1
+#elif defined(OS_LINUX) && !defined(ARCH_CPU_X86_64)
+#define USE_MMX 1
 #else
 #define USE_MMX 0
 #endif
 #endif
 
 #if USE_MMX
 #if defined(_MSC_VER)
 #define EMMS() __asm emms
 #else
 #define EMMS() asm("emms")
 #endif
 #else
 #define EMMS()
 #endif
 
-}  // namespace media
-
 #endif  // MEDIA_BASE_YUV_ROW_H_