Better delay() from magnum branch.
This commit is contained in:
mycroft
parent
5f4063cc56
commit
41cc9cb4f2
|
|
@ -1,5 +1,5 @@
|
|||
/*-
|
||||
* Copyright (c) 1994 Charles Hannum.
|
||||
* Copyright (c) 1993, 1994 Charles Hannum.
|
||||
* Copyright (c) 1991 The Regents of the University of California.
|
||||
* All rights reserved.
|
||||
*
|
||||
|
|
@ -35,7 +35,7 @@
|
|||
* SUCH DAMAGE.
|
||||
*
|
||||
* from: @(#)isa.c 7.2 (Berkeley) 5/13/91
|
||||
* $Id: isa.c,v 1.39 1994/03/06 17:19:09 mycroft Exp $
|
||||
* $Id: isa.c,v 1.40 1994/03/06 17:37:56 mycroft Exp $
|
||||
*/
|
||||
|
||||
/*
|
||||
|
|
@ -50,6 +50,7 @@
|
|||
|
||||
#include <sys/param.h>
|
||||
#include <sys/systm.h>
|
||||
#include <sys/kernel.h>
|
||||
#include <sys/conf.h>
|
||||
#include <sys/file.h>
|
||||
#include <sys/buf.h>
|
||||
|
|
@ -569,99 +570,81 @@ isa_strayintr(d) {
|
|||
|
||||
/*
|
||||
* Wait "n" microseconds.
|
||||
* Relies on timer 1 counting down from (TIMER_FREQ / hz) at
|
||||
* (1 * TIMER_FREQ) Hz.
|
||||
* Relies on timer 1 counting down from (TIMER_FREQ / hz) at TIMER_FREQ Hz.
|
||||
* Note: timer had better have been programmed before this is first used!
|
||||
* (Note that we use `rate generator' mode, which counts at 1:1; `square
|
||||
* wave' mode counts at 2:1).
|
||||
*/
|
||||
#define CF (1 * TIMER_FREQ)
|
||||
|
||||
extern int hz; /* XXX - should be elsewhere */
|
||||
|
||||
void
|
||||
delay(n)
|
||||
int n;
|
||||
{
|
||||
int counter_limit;
|
||||
int prev_tick;
|
||||
int tick;
|
||||
int ticks_left;
|
||||
int sec;
|
||||
int usec;
|
||||
|
||||
#ifdef DELAYDEBUG
|
||||
int gettick_calls = 1;
|
||||
int n1;
|
||||
static int state = 0;
|
||||
|
||||
if (state == 0) {
|
||||
state = 1;
|
||||
for (n1 = 1; n1 <= 10000000; n1 *= 10)
|
||||
delay(n1);
|
||||
state = 2;
|
||||
}
|
||||
if (state == 1)
|
||||
printf("delay(%d)...", n);
|
||||
#endif
|
||||
int limit, tick, otick;
|
||||
|
||||
/*
|
||||
* Read the counter first, so that the rest of the setup overhead is
|
||||
* counted. Guess the initial overhead is 20 usec (on most systems it
|
||||
* takes about 1.5 usec for each of the i/o's in gettick(). The loop
|
||||
* takes about 6 usec on a 486/33 and 13 usec on a 386/20. The
|
||||
* multiplications and divisions to scale the count take a while).
|
||||
* counted.
|
||||
*/
|
||||
prev_tick = gettick();
|
||||
n -= 20;
|
||||
otick = gettick();
|
||||
|
||||
#ifdef __GNUC__
|
||||
/*
|
||||
* Calculate (n * (CF / 1e6)) without using floating point and without
|
||||
* any avoidable overflows.
|
||||
* Calculate ((n * TIMER_FREQ) / 1e6) using explicit assembler code so
|
||||
* we can take advantage of the intermediate 64-bit quantity to prevent
|
||||
* loss of significance.
|
||||
*/
|
||||
sec = n / 1000000;
|
||||
usec = n - sec * 1000000;
|
||||
ticks_left = sec * CF
|
||||
+ usec * (CF / 1000000)
|
||||
+ usec * ((CF % 1000000) / 1000) / 1000
|
||||
+ usec * (CF % 1000) / 1000000;
|
||||
|
||||
counter_limit = TIMER_FREQ / hz;
|
||||
while (ticks_left > 0) {
|
||||
tick = gettick();
|
||||
#ifdef DELAYDEBUG
|
||||
++gettick_calls;
|
||||
#endif
|
||||
if (tick > prev_tick)
|
||||
ticks_left -= prev_tick - (tick - counter_limit);
|
||||
else
|
||||
ticks_left -= prev_tick - tick;
|
||||
prev_tick = tick;
|
||||
n -= 5;
|
||||
if (n < 0)
|
||||
return;
|
||||
{register int m;
|
||||
__asm __volatile("mul %3"
|
||||
: "=a" (n), "=d" (m)
|
||||
: "0" (n), "r" (TIMER_FREQ));
|
||||
__asm __volatile("div %3"
|
||||
: "=a" (n)
|
||||
: "0" (n), "d" (m), "r" (1000000)
|
||||
: "%edx");}
|
||||
#else
|
||||
/*
|
||||
* Calculate ((n * TIMER_FREQ) / 1e6) without using floating point and
|
||||
* without any avoidable overflows.
|
||||
*/
|
||||
n -= 20;
|
||||
{
|
||||
int sec = n / 1000000,
|
||||
usec = n % 1000000;
|
||||
n = sec * TIMER_FREQ +
|
||||
usec * (TIMER_FREQ / 1000000) +
|
||||
usec * ((TIMER_FREQ % 1000000) / 1000) / 1000 +
|
||||
usec * (TIMER_FREQ % 1000) / 1000000;
|
||||
}
|
||||
#ifdef DELAYDEBUG
|
||||
if (state == 1)
|
||||
printf(" %d calls to gettick() at %d usec each\n",
|
||||
gettick_calls, (n + 5) / gettick_calls);
|
||||
#endif
|
||||
|
||||
limit = TIMER_FREQ / hz;
|
||||
|
||||
while (n > 0) {
|
||||
tick = gettick();
|
||||
if (tick > otick)
|
||||
n -= limit - (tick - otick);
|
||||
else
|
||||
n -= otick - tick;
|
||||
otick = tick;
|
||||
}
|
||||
}
|
||||
|
||||
int
|
||||
gettick() {
|
||||
int high;
|
||||
int low;
|
||||
gettick()
|
||||
{
|
||||
u_char lo, hi;
|
||||
|
||||
/*
|
||||
* Protect ourself against interrupts.
|
||||
*/
|
||||
/* Don't want someone screwing with the counter while we're here. */
|
||||
disable_intr();
|
||||
/*
|
||||
* Latch the count for 'timer' (cc00xxxx, c = counter, x = any).
|
||||
*/
|
||||
/* Select counter 0 and latch it. */
|
||||
outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
|
||||
low = inb(TIMER_CNTR0);
|
||||
high = inb(TIMER_CNTR0);
|
||||
lo = inb(TIMER_CNTR0);
|
||||
hi = inb(TIMER_CNTR0);
|
||||
enable_intr();
|
||||
return ((high << 8) | low);
|
||||
return ((hi << 8) | lo);
|
||||
}
|
||||
|
||||
static beeping;
|
||||
|
|
@ -733,7 +716,7 @@ struct isa_device *find_isadev(table, driverp, unit)
|
|||
return NULL;
|
||||
|
||||
table++;
|
||||
}
|
||||
}
|
||||
|
||||
return table;
|
||||
}
|
||||
|
|
|
|||
|
|
@ -1,5 +1,5 @@
|
|||
/*-
|
||||
* Copyright (c) 1994 Charles Hannum.
|
||||
* Copyright (c) 1993, 1994 Charles Hannum.
|
||||
* Copyright (c) 1991 The Regents of the University of California.
|
||||
* All rights reserved.
|
||||
*
|
||||
|
|
@ -35,7 +35,7 @@
|
|||
* SUCH DAMAGE.
|
||||
*
|
||||
* from: @(#)isa.c 7.2 (Berkeley) 5/13/91
|
||||
* $Id: isa.c,v 1.39 1994/03/06 17:19:09 mycroft Exp $
|
||||
* $Id: isa.c,v 1.40 1994/03/06 17:37:56 mycroft Exp $
|
||||
*/
|
||||
|
||||
/*
|
||||
|
|
@ -50,6 +50,7 @@
|
|||
|
||||
#include <sys/param.h>
|
||||
#include <sys/systm.h>
|
||||
#include <sys/kernel.h>
|
||||
#include <sys/conf.h>
|
||||
#include <sys/file.h>
|
||||
#include <sys/buf.h>
|
||||
|
|
@ -569,99 +570,81 @@ isa_strayintr(d) {
|
|||
|
||||
/*
|
||||
* Wait "n" microseconds.
|
||||
* Relies on timer 1 counting down from (TIMER_FREQ / hz) at
|
||||
* (1 * TIMER_FREQ) Hz.
|
||||
* Relies on timer 1 counting down from (TIMER_FREQ / hz) at TIMER_FREQ Hz.
|
||||
* Note: timer had better have been programmed before this is first used!
|
||||
* (Note that we use `rate generator' mode, which counts at 1:1; `square
|
||||
* wave' mode counts at 2:1).
|
||||
*/
|
||||
#define CF (1 * TIMER_FREQ)
|
||||
|
||||
extern int hz; /* XXX - should be elsewhere */
|
||||
|
||||
void
|
||||
delay(n)
|
||||
int n;
|
||||
{
|
||||
int counter_limit;
|
||||
int prev_tick;
|
||||
int tick;
|
||||
int ticks_left;
|
||||
int sec;
|
||||
int usec;
|
||||
|
||||
#ifdef DELAYDEBUG
|
||||
int gettick_calls = 1;
|
||||
int n1;
|
||||
static int state = 0;
|
||||
|
||||
if (state == 0) {
|
||||
state = 1;
|
||||
for (n1 = 1; n1 <= 10000000; n1 *= 10)
|
||||
delay(n1);
|
||||
state = 2;
|
||||
}
|
||||
if (state == 1)
|
||||
printf("delay(%d)...", n);
|
||||
#endif
|
||||
int limit, tick, otick;
|
||||
|
||||
/*
|
||||
* Read the counter first, so that the rest of the setup overhead is
|
||||
* counted. Guess the initial overhead is 20 usec (on most systems it
|
||||
* takes about 1.5 usec for each of the i/o's in gettick(). The loop
|
||||
* takes about 6 usec on a 486/33 and 13 usec on a 386/20. The
|
||||
* multiplications and divisions to scale the count take a while).
|
||||
* counted.
|
||||
*/
|
||||
prev_tick = gettick();
|
||||
n -= 20;
|
||||
otick = gettick();
|
||||
|
||||
#ifdef __GNUC__
|
||||
/*
|
||||
* Calculate (n * (CF / 1e6)) without using floating point and without
|
||||
* any avoidable overflows.
|
||||
* Calculate ((n * TIMER_FREQ) / 1e6) using explicit assembler code so
|
||||
* we can take advantage of the intermediate 64-bit quantity to prevent
|
||||
* loss of significance.
|
||||
*/
|
||||
sec = n / 1000000;
|
||||
usec = n - sec * 1000000;
|
||||
ticks_left = sec * CF
|
||||
+ usec * (CF / 1000000)
|
||||
+ usec * ((CF % 1000000) / 1000) / 1000
|
||||
+ usec * (CF % 1000) / 1000000;
|
||||
|
||||
counter_limit = TIMER_FREQ / hz;
|
||||
while (ticks_left > 0) {
|
||||
tick = gettick();
|
||||
#ifdef DELAYDEBUG
|
||||
++gettick_calls;
|
||||
#endif
|
||||
if (tick > prev_tick)
|
||||
ticks_left -= prev_tick - (tick - counter_limit);
|
||||
else
|
||||
ticks_left -= prev_tick - tick;
|
||||
prev_tick = tick;
|
||||
n -= 5;
|
||||
if (n < 0)
|
||||
return;
|
||||
{register int m;
|
||||
__asm __volatile("mul %3"
|
||||
: "=a" (n), "=d" (m)
|
||||
: "0" (n), "r" (TIMER_FREQ));
|
||||
__asm __volatile("div %3"
|
||||
: "=a" (n)
|
||||
: "0" (n), "d" (m), "r" (1000000)
|
||||
: "%edx");}
|
||||
#else
|
||||
/*
|
||||
* Calculate ((n * TIMER_FREQ) / 1e6) without using floating point and
|
||||
* without any avoidable overflows.
|
||||
*/
|
||||
n -= 20;
|
||||
{
|
||||
int sec = n / 1000000,
|
||||
usec = n % 1000000;
|
||||
n = sec * TIMER_FREQ +
|
||||
usec * (TIMER_FREQ / 1000000) +
|
||||
usec * ((TIMER_FREQ % 1000000) / 1000) / 1000 +
|
||||
usec * (TIMER_FREQ % 1000) / 1000000;
|
||||
}
|
||||
#ifdef DELAYDEBUG
|
||||
if (state == 1)
|
||||
printf(" %d calls to gettick() at %d usec each\n",
|
||||
gettick_calls, (n + 5) / gettick_calls);
|
||||
#endif
|
||||
|
||||
limit = TIMER_FREQ / hz;
|
||||
|
||||
while (n > 0) {
|
||||
tick = gettick();
|
||||
if (tick > otick)
|
||||
n -= limit - (tick - otick);
|
||||
else
|
||||
n -= otick - tick;
|
||||
otick = tick;
|
||||
}
|
||||
}
|
||||
|
||||
int
|
||||
gettick() {
|
||||
int high;
|
||||
int low;
|
||||
gettick()
|
||||
{
|
||||
u_char lo, hi;
|
||||
|
||||
/*
|
||||
* Protect ourself against interrupts.
|
||||
*/
|
||||
/* Don't want someone screwing with the counter while we're here. */
|
||||
disable_intr();
|
||||
/*
|
||||
* Latch the count for 'timer' (cc00xxxx, c = counter, x = any).
|
||||
*/
|
||||
/* Select counter 0 and latch it. */
|
||||
outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
|
||||
low = inb(TIMER_CNTR0);
|
||||
high = inb(TIMER_CNTR0);
|
||||
lo = inb(TIMER_CNTR0);
|
||||
hi = inb(TIMER_CNTR0);
|
||||
enable_intr();
|
||||
return ((high << 8) | low);
|
||||
return ((hi << 8) | lo);
|
||||
}
|
||||
|
||||
static beeping;
|
||||
|
|
@ -733,7 +716,7 @@ struct isa_device *find_isadev(table, driverp, unit)
|
|||
return NULL;
|
||||
|
||||
table++;
|
||||
}
|
||||
}
|
||||
|
||||
return table;
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue