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$NetBSD: patch-main_c,v 1.1 2012/06/18 04:45:47 dholland Exp $
- use gettimeofday() rather than ftime(), which is very obsolete
- don't truncate time_t (or worse, time_t * 1000) to int
Note that because all times used elsewhere are relative, we can get
away with subtracting off the start time like this. We could also
probably get away with truncating to int, except that (a) it's untidy,
(b) likely to attract attention from program checkers, and (c) can
result in formally undefined behavior if we happen to be running
across one of the moments where the milliseconds value passes through
signed overflow.
--- main.c~ 2003-02-05 06:02:40.000000000 +0000
+++ main.c
@@ -15,18 +15,25 @@
#include "protos.h"
-/* get_ms() returns the milliseconds elapsed since midnight,
- January 1, 1970. */
+/* get_ms() returns the milliseconds elapsed since an arbitrary epoch
+ determined at program startup. */
-#include <sys/timeb.h>
-BOOL ftime_ok = FALSE; /* does ftime return milliseconds? */
+#include <sys/time.h>
+BOOL gettimeofday_ok = FALSE; /* are we getting better than just seconds? */
int get_ms()
{
- struct timeb timebuffer;
- ftime(&timebuffer);
- if (timebuffer.millitm != 0)
- ftime_ok = TRUE;
- return (timebuffer.time * 1000) + timebuffer.millitm;
+ static BOOL initialized = 0;
+ static time_t epoch;
+ struct timeval timebuffer;
+ gettimeofday(&timebuffer, NULL);
+ if (!initialized) {
+ epoch = timebuffer.tv_sec;
+ initialized = 1;
+ }
+ timebuffer.tv_sec -= epoch;
+ if (timebuffer.tv_usec != 0)
+ gettimeofday_ok = TRUE;
+ return (timebuffer.tv_sec * 1000) + timebuffer.tv_usec / 1000;
}
@@ -496,9 +503,9 @@ void bench()
printf("\n");
printf("Nodes: %d\n", nodes);
printf("Best time: %d ms\n", t[0]);
- if (!ftime_ok) {
+ if (!gettimeofday_ok) {
printf("\n");
- printf("Your compiler's ftime() function is apparently only accurate\n");
+ printf("Your compiler's gettimeofday() function is apparently only accurate\n");
printf("to the second. Please change the get_ms() function in main.c\n");
printf("to make it more accurate.\n");
printf("\n");
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