1992/0923/pc/clock.c (diff list | history)

1992/0922/sys/src/9/pc/clock.c:16,47 – 1992/0923/sys/src/9/pc/clock.c:16,51 (short | long | prev | next)
rename constants; commenting; rewrite delay to use delayloop, set during clockinit. BUG fix? handle negative delays properly. rsc Fri Mar 4 12:44:25 2005
1991/0709		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 */
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		/* * delay for l milliseconds
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) { int i;
1992/0923		ulong i;
1991/0719		while(--l){ for(i=0; i < 404; i++)
1992/0923		while(l-- > 0) for(i=0; i < delayloop; i++)
1991/0719		; } }
1991/0704		void clockinit(void) {
1992/0922		ulong dc; /* change in counter */
1992/0923		ulong x, y; /* change in counter */
1992/0922
1991/0709		/* * set vector for clock interrupts
1992/0922/sys/src/9/pc/clock.c:51,68 – 1992/0923/sys/src/9/pc/clock.c:55,82
1991/0709		/* * make clock output a square wave with a 1/HZ period */ outb(Tmode, Load0square);
1992/0923		outb(Tmode, Load0|Square);
1991/0709		outb(T0cntr, (Freq/HZ)); /* low byte */ outb(T0cntr, (Freq/HZ)>>8); /* high byte */
1992/0922		/* * measure cpu speed to make delay() system * independent
1992/0923		* measure time for delay(10) with current delayloop count
1992/0922		*/ delay(100); outb(Tmode, Latch0); dc = inb(T0cntr); dc |= inb(T0cntr)<<8;
1992/0923		x = inb(T0cntr); x |= inb(T0cntr)<<8; delay(10); outb(Tmode, Latch0); y = inb(T0cntr); y |= inb(T0cntr)<<8; x -= y; /* * fix count, the factor of 2 is a hack */ delayloop = (delayloop*1193*10)/x; if(delayloop == 0) delayloop = 1;
1991/0704		}
1991/0705		void