port ARGB to 565 dithering SSE2 code to GCC.

source/row_win.cc

 /*
  *  Copyright 2011 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.
  */
 
@@ skipping 815 matching lines @@
     por       xmm2, xmm3   // 12 bytes from 3 for 2
     movdqu    [edx + 16], xmm1   // store 1
     movdqu    [edx + 32], xmm2   // store 2
     lea       edx, [edx + 48]
     sub       ecx, 16
     jg        convertloop
     ret
   }
 }
 
-// 4 pixels
 __declspec(naked)
 void ARGBToRGB565Row_SSE2(const uint8* src_argb, uint8* dst_rgb, int pix) {
   __asm {
     mov       eax, [esp + 4]   // src_argb
     mov       edx, [esp + 8]   // dst_rgb
     mov       ecx, [esp + 12]  // pix
     pcmpeqb   xmm3, xmm3       // generate mask 0x0000001f
     psrld     xmm3, 27
     pcmpeqb   xmm4, xmm4       // generate mask 0x000007e0
     psrld     xmm4, 26
@@ skipping 17 matching lines @@
     packssdw  xmm0, xmm0
     lea       eax, [eax + 16]
     movq      qword ptr [edx], xmm0  // store 4 pixels of RGB565
     lea       edx, [edx + 8]
     sub       ecx, 4
     jg        convertloop
     ret
   }
 }
 
-// 8 pixels
 __declspec(naked)
 void ARGBToRGB565DitherRow_SSE2(const uint8* src_argb, uint8* dst_rgb,
                                 const uint32 dither4, int pix) {
   __asm {
 
     mov       eax, [esp + 4]   // src_argb
     mov       edx, [esp + 8]   // dst_rgb
     movd      xmm6, [esp + 12] // dither4
     mov       ecx, [esp + 16]  // pix
     punpcklbw xmm6, xmm6       // make dither 16 bytes
@@ skipping 5753 matching lines @@
 }
 #endif  // HAS_ARGBLUMACOLORTABLEROW_SSSE3
 
 #endif  // defined(_M_X64)
 #endif  // !defined(LIBYUV_DISABLE_X86) && (defined(_M_IX86) || defined(_M_X64))
 
 #ifdef __cplusplus
 }  // extern "C"
 }  // namespace libyuv
 #endif