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[Qemu-devel] [patch] m68k updates #2
From: |
Richard Zidlicky |
Subject: |
[Qemu-devel] [patch] m68k updates #2 |
Date: |
Wed, 17 Mar 2004 19:07:00 +0100 |
User-agent: |
Mutt/1.4i |
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
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