1994/0716/pc/clock.c (diff list | history)

1994/0715/sys/src/9/pc/clock.c:27,48 – 1994/0716/sys/src/9/pc/clock.c:27,36 (short | long | prev | next)
switch from delay to aamloop (XXX why?) rsc Fri Mar 4 12:44:25 2005
1992/0923		Freq= 1193182, /* Real clock frequency */
1991/0705		};
1992/0923		static ulong delayloop = 1000;
1994/0716		static int cpufreq = 66; static int cputype = 486; static int loopconst = 100;
1992/0923
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) {
1994/0715/sys/src/9/pc/clock.c:95,131 – 1994/0716/sys/src/9/pc/clock.c:83,103
1994/0512		splhi();
1993/1124		}
1994/0716
1994/0302		/*
1994/0610		* experimentally determined
1994/0716		* delay for l milliseconds more or less. delayloop is set by * clockinit() to match the actual CPU speed.
1994/0302		*/ enum
1994/0716		void delay(int l)
1994/0302		{ mul386= 380, mul486= 121,
1994/0610		mul586= 121,
1994/0302		};
1994/0716		aamloop(l*loopconst); }
1994/0302		void printcpufreq(void) { ulong freq; int cpu;                  switch(cpu = x86()){ default:
1994/0610		case 586: freq = mul586; break;
1994/0302		case 486: freq = mul486; break; case 386: freq = mul386; break; } freq *= delayloop; freq /= 10000; print("CPU is a %ud MHz %d\n", freq, cpu);
1994/0716		print("CPU is a %ud Hz %d\n", cpufreq, cputype);
1994/0302		}
1991/0704		void
1994/0715/sys/src/9/pc/clock.c:132,137 – 1994/0716/sys/src/9/pc/clock.c:104,110
1991/0704		clockinit(void) {
1992/0923		ulong x, y; /* change in counter */
1994/0716		ulong cycles, loops;
1992/0922
1991/0709		/* * set vector for clock interrupts
1994/0715/sys/src/9/pc/clock.c:146,157 – 1994/0716/sys/src/9/pc/clock.c:119,140
1991/0709		outb(T0cntr, (Freq/HZ)>>8); /* high byte */
1992/0922		/*
1992/0923		* measure time for delay(10) with current delayloop count
1994/0716		* measure time for the loop * * MOVL loops,CX * aaml1: AAM * LOOP aaml1 * * the time for the loop should be independent from external * cache's and memory system since it fits in the execution * prefetch buffer. *
1992/0922		*/
1994/0716		loops = 10000;
1992/0922		outb(Tmode, Latch0);
1992/0923		x = inb(T0cntr); x |= inb(T0cntr)<<8; delay(10);
1994/0716		aamloop(loops);
1992/0923		outb(Tmode, Latch0); y = inb(T0cntr); y |= inb(T0cntr)<<8;
1994/0715/sys/src/9/pc/clock.c:158,166 – 1994/0716/sys/src/9/pc/clock.c:141,165
1992/0923		x -= y; /*
1993/0915		* fix count
1994/0716		* counter goes at twice the frequency, once per transition, * i.e., twice per the square wave
1992/0923		*/ delayloop = (delayloop*1193*10)/x; if(delayloop == 0) delayloop = 1;
1994/0716		x >>= 1; /* * figure out clock frequency and a loop multiplier for delay(). */ switch(cputype = x86()){ case 386: cycles = 30; break; case 486: cycles = 24; break; default: cycles = 23; break; } cpufreq = (cycles*loops) * (Freq/x); loopconst = (cpufreq/1000)/cycles; /* AAM+LOOP's for 1 ms */
1991/0808		}