[Mplayer-users] [mplayer PATCH] fastmemcpy alignment for any cpu

[Nick Kurshev]

Hello, Arpi, Felix, all!

But what about alignment for any cpu?

It improves speed on any cpu which supports fasmemcpy.

Please compare (Duron-750):
Old results (misaligned dest):
mmx: v2-v1=766128661 = 1009719us  (99.037fps)  148.6MB/s
k6 : v2-v1=627413495 = 826906us  (120.933fps)  181.4MB/s
k7 : v2-v1=221021775 = 291269us  (343.325fps)  515.0MB/s

New results (aligned dest):
mmx: v2-v1=766126582 = 1009433us  (99.066fps)  148.6MB/s
k6 : v2-v1=563458894 = 742432us  (134.692fps)  202.0MB/s
k7 : v2-v1=144598822 = 190540us  (524.824fps)  787.2MB/s

Below patch:

--- fastmemcpy.h.old	Sun Apr 22 23:25:47 2001
+++ fastmemcpy.h	Mon Apr 23 09:29:57 2001
@@ -63,31 +63,33 @@
 	: "memory");\
 }
 
+#ifdef HAVE_SSE
+#define MMREG_SIZE 16
+#else
+#define MMREG_SIZE 8
+#endif
+
 inline static void * fast_memcpy(void * to, const void * from, unsigned len)
 {
 	void *p;
 	int i;
 
-#ifdef HAVE_SSE /* Only P3 (may be Cyrix3) */
-//        printf("fastmemcpy_pre(0x%X,0x%X,0x%X)\n",to,from,len);
-        // Align dest to 16-byte boundary:
-        if((unsigned long)to&15){
-          int len2=16-((unsigned long)to&15);
-          if(len>len2){
-            len-=len2;
-            __asm__ __volatile__(
-	    "rep ; movsb\n"
-	    :"=D" (to), "=S" (from)
-            : "D" (to), "S" (from),"c" (len2)
-	    : "memory");
-          }
-        }
-//        printf("fastmemcpy(0x%X,0x%X,0x%X)\n",to,from,len);
-#endif
-
         if(len >= 0x200) /* 512-byte blocks */
 	{
+	  register unsigned long int delta;
   	  p = to;
+          /* Align destinition to MMREG_SIZE-boundary */
+          delta = ((unsigned long int)to)&(MMREG_SIZE-1);
+          if(delta)
+	  {
+	    delta=MMREG_SIZE-delta;
+	    len -= delta;
+            __asm__ __volatile__(
+	    "rep; movsb"
+	    :"=D" (to), "=S" (from)
+            : "0" (to), "1" (from),"c" (delta)
+	    : "memory");
+	  }    
 	  i = len >> 6; /* len/64 */
 	  len&=63;
 	  

Best regards! Nick


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