1993/1124/pc/clock.c (diff list | history)

pc/clock.c on 1991/0704
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
1992/0923		/* commands */ Latch0= 0x00, /* latch counter 0's value */ Load0= 0x30, /* load counter 0 with 2 bytes */ /* modes */ Square= 0x36, /* perioic square wave */ Freq= 1193182, /* Real clock frequency */
1991/0705		};
1992/0923		static ulong delayloop = 1000;
1991/0719		/*
1992/0923		* delay for l milliseconds more or less. delayloop is set by * clockinit() to match the actual CPU speed.
1991/0719		*/ void delay(int l) {
1992/0923		ulong i;
1991/0719
1992/0923		while(l-- > 0) for(i=0; i < delayloop; i++)
1991/0719		; }
1993/1124		static void clock(Ureg *ur, void *arg) { Proc *p; int nrun = 0; USED(arg); m->ticks++; checkalarms(); mouseclock(); /* * process time accounting */ p = m->proc; if(p){ nrun = 1; p->pc = ur->pc; if (p->state==Running) p->time[p->insyscall]++; } nrun = (nrdy+nrun)*1000; MACHP(0)->load = (MACHP(0)->load*19+nrun)/20; if(up == 0 || (ur->cs&0xffff) != UESEL || up->state != Running) return; if(anyready()) sched(); /* user profiling clock */ spllo(); /* in case we fault */ (*(ulong*)(USTKTOP-BY2WD)) += TK2MS(1); splhi(); }
1991/0704		void clockinit(void) {
1992/0923		ulong x, y; /* change in counter */
1992/0922
1991/0709		/* * set vector for clock interrupts */
1993/1124		setvec(Clockvec, clock, 0);
1991/0709		/* * make clock output a square wave with a 1/HZ period */
1992/0923		outb(Tmode, Load0|Square);
1991/0709		outb(T0cntr, (Freq/HZ)); /* low byte */ outb(T0cntr, (Freq/HZ)>>8); /* high byte */
1992/0922		/*
1992/0923		* measure time for delay(10) with current delayloop count
1992/0922		*/ outb(Tmode, Latch0);
1992/0923		x = inb(T0cntr); x |= inb(T0cntr)<<8; delay(10); outb(Tmode, Latch0); y = inb(T0cntr); y |= inb(T0cntr)<<8; x -= y; /*
1993/0915		* fix count
1992/0923		*/ delayloop = (delayloop*1193*10)/x; if(delayloop == 0) delayloop = 1;
1991/0808		}