[9fans] (no subject)

[Leendert van Doorn <leendert@watson.ibm.com>]

I was indeed an intern but in 1995, I was also the author of the x86
port of Amoeba and wrote that timer code around 1990. My code never
contained the offending cpuspeed routine. In fact, I just looked at
the RCS repository that still exists at the VU and it isn't in there
either. Who ever added cpuspeed to this file, it was not one of the
VU Amoeba developers.

	Leendert


# From: philw@entrisphere.com
# Date: Sat Feb 22 15:35:26 EST 2003
# To: 9fans@cse.psu.edu
# Subject: RE: [9fans] A quite amusing thing...
#
#
# Leendert van Doorn was a summer student at the labs that year I think
#
# phil
#
# 	-----Original Message-----
# 	From: Russ Cox [mailto:rsc@plan9.bell-labs.com]
# 	Sent: Sat 2/22/2003 12:30 PM
# 	To: 9fans@cse.psu.edu
# 	Cc:
# 	Subject: Re: [9fans] A quite amusing thing...
#
#
#
# 	That _is_ fairly amusing.
#
# 	We've had a form of that code (including the big
# 	comment) in our source tree since July 15, 1994.
# 	But the 1994 code didn't have the for loop to run
# 	until loops got big enough (it assumed 10000 was
# 	enough) and it didn't have all the clock frequency
# 	stuff (which got added later).
#
# 	So either Plan 9 copied Amoeba back in 1994 (before
# 	the original project was terminated) and has been
# 	secretly tracking the code since then, or Amoeba copied
# 	Plan 9 some time later after the code was changed to
# 	look more like it does today.  I know where my money is.
#
# 	Also, I downloaded the original Amoeba code and the
# 	pit.c looked nothing like the Plan 9 code as of 1996.
#
# 	Below you'll find Plan 9's clock.c from 1994, Amoeba's
# 	pit.c from 1996, and Amoeba's pit.c from today.
# 	Note the difference between the last two.  Sure looks like
#
# 	 * Stefan Bosse (12/1999-7/2000)
# 	 * sbosse@physik.uni-bremen.de
# 	 *
# 	 * -> pit_hw_milli now default routine with 1ms resolution
# 	 * -> cpuspeed measurement and delay loop reference
#
# 	copied the Plan 9 code.
#
# 	> Hmm... It is possible too that Amoeba developer's have copied this co
de
# 	> but I doubt it.
#
# 	Why?
#
# 	Russ
#
# 	/* --rw-rw-r-- M 3014 jmk sys 2766 Jul 15  1994 sys/src/brazil/pc/clock
.c */
#
# 	void
# 	clockinit(void)
# 	{
# 	        ulong x, y;     /* change in counter */
# 	        ulong cycles, loops;
#
# 	        /*
# 	         *  set vector for clock interrupts
# 	         */
# 	        setvec(Clockvec, clock, 0);
#
# 	        /*
# 	         *  set clock for 1/HZ seconds
# 	         */
# 	        outb(Tmode, Load0|Square);
# 	        outb(T0cntr, (Freq/HZ));        /* low byte */
# 	        outb(T0cntr, (Freq/HZ)>>8);     /* high byte */
#
# 	        /*
# 	         *  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.
# 	         *
# 	         */
# 	        loops = 10000;
# 	        outb(Tmode, Latch0);
# 	        x = inb(T0cntr);
# 	        x |= inb(T0cntr)<<8;
# 	        aamloop(loops);
# 	        outb(Tmode, Latch0);
# 	        y = inb(T0cntr);
# 	        y |= inb(T0cntr)<<8;
# 	        x -= y;
#
# 	        /*
# 	         *  counter  goes at twice the frequency, once per transition,
# 	         *  i.e., twice per the square wave
# 	         */
# 	        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
*/
# 	}
#
#
# 	/*      @(#)pit.c       1.4     94/04/06 09:23:12 */
# 	/*
# 	 * Copyright 1994 Vrije Universiteit, The Netherlands.
# 	 * For full copyright and restrictions on use see the file COPYRIGHT in
 the
# 	 * top level of the Amoeba distribution.
# 	 */
#
# 	/*
# 	 * pit.c
# 	 *
# 	 * Driver for the 8254 timer (PIT). The i8254 timer has three timer cha
nnels
# 	 * of which only one (channel 0) is available for timer interrupts. The
 other
# 	 * channels are used for the speaker and memory refresh.
# 	 *
# 	 * Author:
# 	 *      Leendert van Doorn
# 	 */
# 	#include <amoeba.h>
# 	#include <assert.h>
# 	INIT_ASSERT
# 	#include <fault.h>
# 	#include <bool.h>
# 	#include "sys/proto.h"
# 	#include "i386_proto.h"
# 	#include "pit.h"
#
# 	#ifndef PIT_DEBUG
# 	#define PIT_DEBUG       0
# 	#endif
#
# 	static int pit_debug;                   /* current debug level */
#
# 	#ifdef notyet
# 	static uint32 pit_hw_milli();
# 	#endif
# 	static void pit_intr();
#
# 	/*
# 	 * Initialize channel 0 of the i8254A timer
# 	 */
# 	void
# 	pit_init()
# 	{
# 	    register uint32 counter = (PIT_FREQ * PIT_INTERVAL) / 1000L;
#
# 	#ifndef NDEBUG
# 	    if ((pit_debug = kernel_option("pit")) == 0)
# 	        pit_debug = PIT_DEBUG;
# 	    if (pit_debug > 1)
# 	        printf("pit_init(), pit_interval = 0x%x (%d), counter = %x\n",
# 	            PIT_INTERVAL, PIT_INTERVAL, counter);
# 	#endif
#
# 	    /* set timer to run continuously */
# 	    assert(counter <= 0xFFFF);
# 	    out_byte(PIT_MODE, PIT_MODE3);
# 	    out_byte(PIT_CH0, (int) (counter & 0xFF));
# 	    out_byte(PIT_CH0, (int) ((counter >> 8) & 0xFF));
#
# 	#ifdef notyet
# 	    /* I still have to thoroughly test this */
# 	    set_hw_milli(pit_hw_milli);
# 	#endif
#
# 	    setirq(PIT_IRQ, pit_intr);
# 	    pic_enable(PIT_IRQ);
# 	}
#
# 	/*
# 	 * Read i8254's channel 0 counter. The counter decrements at twice the
# 	 * timer frequency (one full cycle for each half of a square wave).
# 	 */
# 	uint16
# 	pit_channel0()
# 	{
# 	    register uint16 counter;
#
# 	    out_byte(PIT_MODE, PIT_LC);
# 	    counter = in_byte(PIT_CH0), counter |= (in_byte(PIT_CH0) << 8);
# 	    return counter;
# 	}
#
# 	/*
# 	 * Delay for at least ``msec'' milli seconds
# 	 */
# 	void
# 	pit_delay(msec)
# 	    int msec;
# 	{
# 	    register uint16 current, previous, diff;
# 	    register uint32 total;
#
# 	    /*
# 	     * The counter decrements at twice the timer frequency
# 	     * (one full cycle for each half of a square wave).
# 	     */
# 	    diff = 100; /* just in case */
# 	    total = (uint32) msec * (2 * PIT_FREQ / 1000);
# 	    previous = pit_channel0();
# 	    for (;;) {
# 	        current = pit_channel0();
# 	        if (current < previous)
# 	            diff = previous - current;
# 	        if (diff >= total)
# 	            break;
# 	        total -= diff;
# 	        previous = current;
# 	    }
# 	}
#
# 	#ifdef notyet
# 	/*
# 	 * Return number of actual milli-seconds that have passed
# 	 */
# 	static uint32
# 	pit_hw_milli()
# 	{
# 	    extern uint32 milli_uptime;
# 	    register uint32 milli;
# 	    register int flags;
# 	    uint16 counter;
# 	    int status;
#
# 	    flags = get_flags(); disable();
# 	    out_byte(PIT_MODE, PIT_RB);
# 	    out_byte(PIT_MODE, 0xC2);
# 	    status = in_byte(PIT_CH0);
# 	    counter = in_byte(PIT_CH0), counter |= (in_byte(PIT_CH0) << 8);
# 	    milli = milli_uptime + (PIT_INTERVAL / 2) *
# 	        (counter / (PIT_FREQ * PIT_INTERVAL) / 1000L);
# 	    if ((status & 0x80) == 0) milli += PIT_INTERVAL/2;
# 	    set_flags(flags);
# 	    return milli;
# 	}
# 	#endif
#
# 	/*
# 	 * The actual clock interrupt
# 	 */
# 	/* ARGSUSED */
# 	static void
# 	pit_intr(reason, frame)
# 	    int reason;
# 	    struct fault *frame;
# 	{
# 	    void sweeper_run();
# 	    void flp_motoroff();
# 	    extern int motortime;
#
# 	#ifdef MCA
# 	    /* ps/2 clock needs to be told to stop interrupting */
# 	    out_byte(0x61, in_byte(0x61) | 0x80);
# 	#endif
#
# 	    enqueue(sweeper_run, (long) PIT_INTERVAL);
#
# 	#if (defined(ISA) || defined(MCA)) && !defined(NOFLOPPY)
# 	    /* stop running floppy motor */
# 	    if (motortime != 0 && --motortime == 0)
# 	        flp_motoroff();
# 	#endif
# 	}
#
#
# 	/*
# 	 * This file is part of the FIREBALL AMOEBA System.
# 	 *
# 	 *
# 	 * Last modified:
# 	 *              18/02/01
# 	 *
# 	 * Stefan Bosse (12/1999-7/2000)
# 	 * sbosse@physik.uni-bremen.de
# 	 *
# 	 * -> pit_hw_milli now default routine with 1ms resolution
# 	 * -> cpuspeed measurement and delay loop reference
# 	 *
# 	 *
# 	 *
# 	 * FIREBALL AMOEBA is free software; you can redistribute it and/or
# 	 * modify it under the terms of the GNU General Public License as
# 	 * published by the Free Software Foundation; version 2.
# 	 *
# 	 * The FIREBALL AMOEBA is distributed in the hope that it will be usefu
ll,
# 	 * but WITHOUT ANY WARRANTY; without even implied warranty of
# 	 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# 	 * General Public License for more details.
# 	 *
# 	 * Original Copyright: Vrije Universiteit, The Netherlands.
# 	 */
#
#
#
#
# 	/*
# 	 * pit.c
# 	 *
# 	 * Driver for the 8254 timer (PIT). The i8254 timer has three timer cha
nnels
# 	 * of which only one (channel 0) is available for timer interrupts. The
 other
# 	 * channels are used for the speaker and memory refresh.
# 	 *
# 	 * Author:
# 	 *      Leendert van Doorn
# 	 */
#
#
# 	#include <amoeba.h>
# 	#include <assert.h>
# 	INIT_ASSERT
# 	#include <fault.h>
# 	#include <bool.h>
# 	#include "sys/proto.h"
# 	#include "i386_proto.h"
# 	#include <irq.h>
# 	#include "pit.h"
# 	#include <cpu.h>
#
# 	#ifndef PIT_DEBUG
# 	#define PIT_DEBUG       0
# 	#endif
#
# 	#ifdef STATISTICS
# 	static unsigned long pit_hw_milli_count=0;
# 	static unsigned long pit_hw_milli_wrap1=0;
# 	static unsigned long pit_hw_milli_wrap2=0;
# 	static unsigned long pit_delay_count=0;
# 	#endif
#
# 	static int pit_debug;                   /* current debug level */
# 	static int initialized=0;
#
# 	#ifdef PIT_HW_MILLI
# 	static uint32 pit_hw_milli();
# 	#endif
# 	static void pit_intr();
#
# 	/*
# 	 * milli_uptime will be incremented in sweeper_run, but it's delayed
# 	 * because of enqueue() handling.
# 	 * milli_uptime should be handled ***here***.
# 	 * Hack: Local we use timer_ticks for pit_hw_milli(), incremented in lo
w
# 	 * level ISR below...
# 	 */
# 	unsigned long timer_ticks=0;
#
# 	/* for time monotony checking; we have a serious problem with
# 	 * this faulty timer hardware
# 	 */
# 	static unsigned long last_time=0;
#
# 	/*
# 	 * Initialize channel 0 of the i8254A timer
# 	 */
# 	void
# 	pit_init()
# 	{
# 	    register uint32 counter = (PIT_FREQ * PIT_INTERVAL) / 1000L;
#
#
# 	    if(!initialized)
# 	    {
#
# 	        initialized=1;
# 	#ifndef NDEBUG
# 	        if ((pit_debug = kernel_option("pit")) == 0)
# 	                pit_debug = PIT_DEBUG;
# 	        if (pit_debug > 1)
# 	                printf("pit_init(), pit_interval = 0x%x (%d), counter =
 %x\n",
# 	                       PIT_INTERVAL, PIT_INTERVAL, counter);
# 	#endif
#
# 	        /* set timer to run continuously */
# 	        assert(counter <= 0xFFFF);
#
# 	        if(check_region(PIT_CH0,4)<0)
# 	                panic("Some fool allocated timer ports");
# 	        request_region(PIT_CH0,4,"PIT");
#
# 	        out_byte(PIT_MODE, PIT_MODE2);
#
# 	        out_byte(PIT_CH0, (int) (counter & 0xFF));
# 	        out_byte(PIT_CH0, (int) ((counter >> 8) & 0xFF));
#
# 	#ifdef PIT_HW_MILLI
# 	        /* I still have to thoroughly test this */
# 	        /* SB: still timer wrap problems; but time monotonie is gurante
ed */
# 	        set_hw_milli(pit_hw_milli);
# 	#endif
#
# 	        if(request_irq(PIT_IRQ,
# 	                       pit_intr,
# 	                       SA_NORMAL,
# 	                       "PIT",
# 	                       (void *)NULL)!=0)
# 	                panic("Some fool allocated timer irq");
#
# 	        enable_irq(PIT_IRQ);
# 	        /*pic_enable(PIT_IRQ);*/
# 	    }
# 	}
#
# 	/*
# 	 * Read i8254's channel 0 counter. The counter decrements at twice the
# 	 * timer frequency (one full cycle for each half of a square wave).
# 	 */
# 	uint16
# 	pit_channel0()
# 	{
# 	    register uint16 counter;
# 	    unsigned long flags;
#
# 	    save_flags(flags);cli();
# 	    out_byte(PIT_MODE, PIT_LC);
# 	    counter = in_byte(PIT_CH0), counter |= (in_byte(PIT_CH0) << 8);
# 	    restore_flags(flags);
# 	    return counter;
# 	}
#
# 	/*
# 	 * Delay for at least ``msec'' milli seconds
# 	 */
# 	void
# 	pit_delay(msec)
# 	    int msec;
# 	{
# 	    register uint16 current, previous, diff;
# 	    register uint32 total;
#
#
# 	#ifdef STATISTICS
# 	    pit_delay_count++;
# 	#endif
# 	    /*
# 	     * The counter decrements at twice the timer frequency
# 	     * (one full cycle for each half of a square wave).
# 	     */
# 	    diff = 100; /* just in case */
# 	    total = (uint32) msec * (PIT_FREQ / 1000);
# 	    previous = pit_channel0();
# 	    for (;;) {
# 	        current = pit_channel0();
# 	        if (current < previous)
# 	            diff = previous - current;
# 	        if (diff >= total)
# 	            break;
# 	        total -= diff;
# 	        previous = current;
# 	    }
# 	}
#
#
# 	#ifdef PIT_HW_MILLI
# 	/*
# 	 * Return number of actual milli-seconds that have passed
# 	 */
# 	static uint32
# 	pit_hw_milli()
# 	{
# 	    extern uint32 milli_uptime;
# 	    register uint32 milli;
# 	    uint16 counter,counter2;
# 	    int status,status2;
# 	    unsigned long flags;
# 	    unsigned long ticks=timer_ticks;
#
#
#
# 	#ifdef STATISTICS
# 	    pit_hw_milli_count++;
# 	#endif
#
# 	    save_flags(flags);cli();
# 	    /* Select timer0 and latch counter value. */
# 	    out_byte(PIT_MODE,PIT_LC);
# 	    counter = in_byte(PIT_CH0), counter |= (in_byte(PIT_CH0) << 8);
# 	    restore_flags(flags);
#
# 	    milli = timer_ticks*PIT_INTERVAL +
# 	        (1000*(((PIT_FREQ*PIT_INTERVAL)/1000) - counter )/(PIT_FREQ) );
#
#
# 	    /* check time monotony */
# 	    if(milli<last_time)
# 	    {
# 	#ifdef STATISTICS
# 	        pit_hw_milli_wrap1++;
# 	#endif
# 	        if(ticks<timer_ticks)
# 	        {
# 	                milli=timer_ticks*PIT_INTERVAL;
# 	#ifdef STATISTICS
# 	                pit_hw_milli_wrap2++;
# 	#endif
# 	        }
# 	        else
# 	                milli=last_time;
# 	    }
#
#
# 	    last_time=milli;
#
#
# 	    if(ticks<timer_ticks) /* Between start and here pit_intr was called
 */
# 	        return (timer_ticks*PIT_INTERVAL);
# 	    else
# 	        return milli;
# 	}
# 	#endif
#
# 	/*
# 	 * The actual clock interrupt
# 	 */
# 	/* ARGSUSED */
# 	#ifdef __KERNEL__       /* Work with Linux-ISR  */
# 	static void
# 	pit_intr(reason,dev_idt,frame)
# 	    int reason;
# 	    void *dev_idt;
# 	    struct fault *frame;
# 	#else
# 	static void
# 	pit_intr(reason,frame)
# 	    int reason;
# 	    struct fault *frame;
# 	#endif
# 	{
# 	    void sweeper_run();
# 	    void flp_motoroff();
# 	    extern int motortime;
#
#
# 	    timer_ticks++;
#
# 	#ifdef MCA
# 	    /* ps/2 clock needs to be told to stop interrupting */
# 	    out_byte(0x61, in_byte(0x61) | 0x80);
# 	#endif
#
# 	    enqueue(sweeper_run, (long) PIT_INTERVAL);
#
# 	#if (defined(ISA) || defined(MCA)) && !defined(NOFLOPPY)
# 	    /* stop running floppy motor */
# 	    if (motortime != 0 && --motortime == 0)
# 	        flp_motoroff();
# 	#endif
# 	}
#
# 	#ifdef STATISTICS
# 	int
# 	pit_stat(begin,end)
# 	char    *begin;
# 	char    *end;
# 	{
# 	        char *p;
# 	        int     i;
#
# 	        p=bprintf(begin,end,"**** Hardware Timer statistics *****\n");
# 	        p=bprintf(p,end,"pit_hw_milli() calls: %d\n",
# 	                  pit_hw_milli_count);
# 	        p=bprintf(p,end,"pit_hw_milli time wrap check failed: %d\n",
# 	                  pit_hw_milli_wrap1);
# 	        p=bprintf(p,end,"pit_hw_milli dirty ticks increment: %d\n",
# 	                  pit_hw_milli_wrap2);
#
# 	        p=bprintf(p,end,"pit_delay() calls: %d\n",
# 	                  pit_delay_count);
#
# 	        return p-begin;
# 	}
# 	#endif
#
# 	/* For cpu speed measurement. We need timer access. */
#
# 	void
# 	cpuspeed(int aalcycles, int havecycleclock)
# 	{
# 	        int cpufreq, loops, incr, x, y;
# 	        unsigned long ax1,dx1,ax2,dx2,a,b;
#
# 	        pit_init();
#
# 	        /* find biggest loop that doesn't wrap */
# 	        incr = 16000000/(aalcycles*HZ*2);
# 	        x = 2000;
# 	        for(loops = incr; loops < 64*1024; loops += incr) {
#
# 	                /*
# 	                 *  measure time for the loop
# 	                 *
# 	                 *                      MOVL    loops,CX
# 	                 *      aaml1:          AAM
# 	                 *                      LOOP    aaml1
# 	                 *
# 	                 *  the time for the loop should be independent of exte
rnal
# 	                 *  cache and memory system since it fits in the execut
ion
# 	                 *  prefetch buffer.
# 	                 *
# 	                 */
#
# 	                /* Beware of counter reset's (wraps)... */
#
# 	                /* Read the cpu internal clock if available */
# 	                if(havecycleclock)
# 	                        rdmsr(0x10, &ax1,&dx1);
# 	                x = (int)pit_channel0();
#
# 	                aamloop(loops);
#
# 	                if(havecycleclock)
# 	                        rdmsr(0x10, &ax2,&dx2);
#
# 	                y = (int)pit_channel0();
#
# 	                x -= y;
#
# 	                if(x < 0)
# 	                        x += PIT_FREQ/PIT_HZ;
#
# 	                if(x > PIT_FREQ/(3*PIT_HZ))
# 	                        break;
# 	        }
#
# 	        /*
# 	         *  figure out clock frequency and a loop multiplier for delay(
).
# 	         *  n.b. counter goes up by 2*PIT_FREQ
# 	         */
# 	        cpufreq = loops*((aalcycles*PIT_FREQ)/x);
# 	        cpu.loopconst = (cpufreq/1000)/aalcycles; /* AAM+LOOP's for 1ms
 */
#
# 	        /* check aalcycle value */
# 	        if(kernel_option("cud") == 1)
# 	                printf("cpuspeed: aalcycle MHz=%d\n",
# 	                        (cpufreq + cpufreq/200)/1000000);
#
# 	        if(havecycleclock){
#
#
# 	                if(dx2 == dx1)
# 	                        b = (ax2-ax1);
# 	                else    /* counter wrap */
# 	                        b = (ax2+0xffffffff-ax1);
#
# 	                b /= x;
# 	                b *= PIT_FREQ;
#
#
# 	                /*
# 	                 *  round to the nearest megahz
# 	                 */
# 	                cpu.cpumhz = (b+500000)/1000000L;
# 	                cpu.cpuhz = b;
# 	        } else {
# 	                /*
# 	                 *  add in possible 0.5% error and convert to MHz
# 	                 */
# 	                cpu.cpumhz = (cpufreq + cpufreq/200)/1000000;
# 	                cpu.cpuhz = cpufreq;
# 	        }
#
#
# 	}
#
#
#
#
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--
Leendert van Doorn                                    <leendert@watson.ibm.com>
IBM T.J. Watson Research Center                       (914) 784-7831
30 Saw Mill River Road, Hawthorne, NY 10532