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Remove delaytab and just compute the reminder directly. This requires

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two muls and a shift, which needs at most 2ms on a 25MHz i386 and should
end up as fast as delay(1) was before due to using a reminder of 2.
Discussed with ad@.
This commit is contained in:
joerg 2007-12-28 14:05:22 +00:00
parent ac257c9a5b
commit 02d07b4e9d
1 changed files with 3 additions and 10 deletions
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13
sys/arch/x86/isa/clock.c
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@ -1,4 +1,4 @@
/* $NetBSD: clock.c,v 1.15 2007/12/09 20:27:49 jmcneill Exp $ */
/* $NetBSD: clock.c,v 1.16 2007/12/28 14:05:22 joerg Exp $ */
/*-
* Copyright (c) 1990 The Regents of the University of California.
@ -121,7 +121,7 @@ WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: clock.c,v 1.15 2007/12/09 20:27:49 jmcneill Exp $");
__KERNEL_RCSID(0, "$NetBSD: clock.c,v 1.16 2007/12/28 14:05:22 joerg Exp $");
/* #define CLOCKDEBUG */
/* #define CLOCK_PARANOIA */
@ -475,11 +475,6 @@ i8254_delay(unsigned int n)
{
unsigned int cur_tick, initial_tick;
int remaining;
static const int delaytab[26] = {
0, 2, 3, 4, 5, 6, 7, 9, 10, 11,
12, 13, 15, 16, 17, 18, 19, 21, 22, 23,
24, 25, 27, 28, 29, 30,
};
/* allow DELAY() to be used before startrtclock() */
if (!rtclock_init)
@ -491,9 +486,7 @@ i8254_delay(unsigned int n)
*/
initial_tick = gettick();
if (n <= 25)
remaining = delaytab[n];
else if (n <= UINT_MAX / TIMER_FREQ) {
if (n <= UINT_MAX / TIMER_FREQ) {
/*
* For unsigned arithmetic, division can be replaced with
* multiplication with the inverse and a shift.