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Date: Wed, 17 Mar 2004 19:07:00 +0100
From: Richard Zidlicky <rz@linux-m68k.org>
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Subject: [Qemu-devel] [patch] m68k updates #2
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To: Fabrice Bellard <fabrice@bellard.org>, Qemu ML <qemu-devel@nongnu.org>

Hi,

this is experimantal and I am open to suggestions how to do
it better. m68k does not have any rdtsc equivalent so I have
to work around it like this - normal timer may have very low
resolution (around 1/200 s).
Afaics the better alternative would be to count instructions
in generated code blocks and calculate clock value from this
somehow.

Richard


diff -urN qemu-cvs/vl.c qemu-cvs-new/vl.c
--- qemu-cvs/vl.c	Mon Mar 15 00:43:15 2004
+++ qemu-cvs-new/vl.c	Wed Mar 17 18:35:55 2004
@@ -346,6 +346,30 @@
     return val;
 }
 
+#elif defined(__mc68020__)
+
+/* crude hack to get some sort of rdtsc support */
+
+#include <sys/time.h>
+static int64_t cputicks=0;
+static struct timeval lastcptcall={0,0};
+
+/* assume 5 MHz Pentium, min 80 ticks between rdtsc calls */
+
+int64_t cpu_get_real_ticks(void)
+{
+     struct timeval tp;
+     gettimeofday(&tp,(void*)0);
+     if (tp.tv_sec == lastcptcall.tv_sec &&
+	 tp.tv_usec == lastcptcall.tv_usec ){
+       cputicks += 1;
+     } else {
+       cputicks=0;
+       lastcptcall=tp;
+     }
+     return ((int64_t)tp.tv_sec*1000000+tp.tv_usec)*5+cputicks;
+}
+
 #else
 #error unsupported CPU
 #endif