From: Tim Thompson <tjt@...>
Date: 2001-03-05T14:29:13+09:00
Subject: [ruby-talk:11990] higher-resolution Time for Win32

I want to use Ruby for realtime MIDI and audio on Windows.
To do that, I need high-resolution timing.  The existing C code
in Ruby uses gettimeofday() to get the current time.
I have made a modification so that, on Windows, it uses the
timeGetTime() API to get a higher-resolution time.

Before this change, Ruby's Time.now.tv_usec value on Windows 98
was quantized to a large (40-50 millisecond) amount, because
of the poor implementation of gettimeofday() in Windows.

After this change, Ruby's Time.now.tv_usec value on Windows 98
has millisecond-resolution (i.e. the resolution of
the timeGetTime() API).

I've tried to make a minimal (but complete) change,
by added a rb_gettimeofday() function that all code uses
instead of gettimeofday().  The winmm.lib library needs
to be added to the makefile as well.   A 'diff -u' for 1.6.2
is enclosed at the end of this message.

I've tested the change on both Win98 and Linux.

Any chance this change can be made in the official distribution?

    ...Tim Thompson...tjt@nosuch.com...

================================================================

--- win32/Makefile.sub.original	Sun Mar  4 20:27:04 2001
+++ win32/Makefile.sub	Sun Mar  4 20:33:31 2001
@@ -35,7 +35,7 @@
 LDFLAGS = $(CFLAGS) -Fm
 XLDFLAGS = 
 #EXTLIBS = 
-LIBS = user32.lib advapi32.lib wsock32.lib $(EXTLIBS)
+LIBS = user32.lib advapi32.lib wsock32.lib $(EXTLIBS) winmm.lib
 MISSING = crypt.obj alloca.obj win32.obj isinf.obj isnan.obj
 LDSHARED = 
 DLDFLAGS = 


--- eval.c.original	Sun Mar  4 20:26:44 2001
+++ eval.c	Sun Mar  4 20:03:09 2001
@@ -6771,7 +6771,7 @@
 timeofday()
 {
     struct timeval tv;
-    gettimeofday(&tv, NULL);
+    rb_gettimeofday(&tv);
     return (double)tv.tv_sec + (double)tv.tv_usec * 1e-6;
 }
 

--- random.c.original	Sun Mar  4 20:27:15 2001
+++ random.c	Sun Mar  4 20:03:25 2001
@@ -119,7 +119,7 @@
 	static int n = 0;
 	struct timeval tv;
 
-	gettimeofday(&tv, 0);
+	rb_gettimeofday(&tv);
 	seed = tv.tv_sec ^ tv.tv_usec ^ getpid() ^ n++;
     }
     else {
@@ -143,7 +143,7 @@
     if (first) {
 	struct timeval tv;
 
-	gettimeofday(&tv, 0);
+	rb_gettimeofday(&tv);
 	rand_init(tv.tv_sec ^ tv.tv_usec ^ getpid());
     }
     switch (TYPE(vmax)) {


--- time.c.original	Sun Mar  4 20:27:31 2001
+++ time.c	Sun Mar  4 21:10:12 2001
@@ -26,6 +26,10 @@
 #endif
 #endif /* NT */
 
+#ifdef NT
+#include <mmsystem.h>
+#endif
+
 #ifdef HAVE_SYS_TIMES_H
 #include <sys/times.h>
 #endif
@@ -50,6 +54,31 @@
     Data_Get_Struct(obj, struct time_object, tobj);\
 }
 
+int
+rb_gettimeofday(struct timeval *tvp)
+{
+#ifdef NT
+    static int initialized = 0;
+    static struct timeval tv0;
+    static long tm0;
+    long dt;
+
+    if ( ! initialized ) {
+	initialized = 1;
+	tm0 = timeGetTime();
+	if ( gettimeofday(&tv0, 0) < 0 )
+	    return -1;
+    }
+    dt = timeGetTime() - tm0;
+    *tvp = tv0;
+    tvp->tv_sec += dt / 1000;
+    tvp->tv_usec += 1000 * (dt % 1000);
+    return 0;
+#else
+    return gettimeofday(tvp, 0);
+#endif	/* NT */
+}
+
 static VALUE
 time_s_now(klass)
     VALUE klass;
@@ -60,7 +89,7 @@
     obj = Data_Make_Struct(klass, struct time_object, 0, free, tobj);
     tobj->tm_got=0;
 
-    if (gettimeofday(&tobj->tv, 0) < 0) {
+    if (rb_gettimeofday(&tobj->tv) < 0) {
 	rb_sys_fail("gettimeofday");
     }
 
@@ -294,7 +323,7 @@
     struct tm *tm;
     long t, diff;
 
-    if (gettimeofday(&tv, 0) < 0) {
+    if (rb_gettimeofday(&tv) < 0) {
 	rb_sys_fail("gettimeofday");
     }
     guess = tv.tv_sec;

================================================================