1992/0820/pc/clock.c (diff list | history)

1992/0820/sys/src/9/pc/clock.c:1,96 – 1992/0922/sys/src/9/pc/clock.c:1,108 (short | long | prev | next)
Measure cpu speed to make delay system-independent. rsc Fri Mar 4 12:44:25 2005
1991/0704		#include "u.h"
1992/0321		#include "../port/lib.h"
1991/0704		#include "mem.h" #include "dat.h" #include "fns.h" #include "io.h"
1991/0706		#include "ureg.h"
1991/0704
1991/0705		/* * 8253 timer */ enum {
1991/0709		T0cntr= 0x40, /* counter ports */ T1cntr= 0x41, /* ... */ T2cntr= 0x42, /* ... */ Tmode= 0x43, /* mode port */
1991/0705
1991/0709		Load0square= 0x36, /* load counter 0 with 2 bytes, * output a square wave whose * period is the counter period */
1992/0922		Latch0= 0x06,
1991/0709		Freq= 1193182, /* Real clock frequency */
1991/0705		};
1991/0719		/* * delay for l milliseconds */ void delay(int l) { int i; while(--l){ for(i=0; i < 404; i++) ; } }
1991/0704		void clockinit(void) {
1992/0922		ulong dc; /* change in counter */
1991/0709		/* * set vector for clock interrupts */
1991/0716		setvec(Clockvec, clock);
1991/0709		/* * make clock output a square wave with a 1/HZ period */ outb(Tmode, Load0square); outb(T0cntr, (Freq/HZ)); /* low byte */ outb(T0cntr, (Freq/HZ)>>8); /* high byte */
1992/0922		/* * measure cpu speed to make delay() system * independent */ delay(100); outb(Tmode, Latch0); dc = inb(T0cntr); dc |= inb(T0cntr)<<8;
1991/0704		}
1991/0705		void
1991/0706		clock(Ureg *ur)
1991/0705		{
1991/0706		Proc *p;
1991/1113		int nrun = 0;
1991/0706
1991/0705		m->ticks++;
1991/0711		checkalarms();
1991/1113		uartclock();
1991/0711
1991/0808		/* * process time accounting */
1991/0706		p = m->proc; if(p){
1991/1113		nrun = 1;
1991/0711		p->pc = ur->pc;
1991/0706		if (p->state==Running) p->time[p->insyscall]++; }
1991/1113		nrun = (nrdy+nrun)*1000; MACHP(0)->load = (MACHP(0)->load*19+nrun)/20;
1991/0801
1991/0802		if(u && p && p->state==Running){
1991/0808		/* * preemption */
1991/0730		if(anyready()){ if(p->hasspin) p->hasspin = 0; else sched(); }
1991/1115		if((ur->cs&0xffff) == UESEL){ spllo(); /* in case we fault */ (*(ulong*)(USTKTOP-BY2WD)) += TK2MS(1); /* profiling clock */ splhi(); }
1991/0802		}
1991/0808		}