patch-2.1.66 linux/drivers/char/ftape/calibr.c

• Lines: 184
• Date: Wed Dec 31 16:00:00 1969
• Orig file: v2.1.65/linux/drivers/char/ftape/calibr.c
• Orig date: Thu Mar 14 01:51:41 1996

diff -u --recursive --new-file v2.1.65/linux/drivers/char/ftape/calibr.c linux/drivers/char/ftape/calibr.c
@@ -1,183 +0,0 @@
-/* Yo, Emacs! we're -*- Linux-C -*-
- *
- *      Copyright (C) 1993-1995 Bas Laarhoven.
-
- This program 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; either version 2, or (at your option)
- any later version.
-
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- GNU General Public License for more details.
-
- You should have received a copy of the GNU General Public License
- along with this program; see the file COPYING.  If not, write to
- the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
-
- *      GP calibration routine for processor speed dependent
- *      functions.
- */
-
-#include <linux/errno.h>
-#include <linux/sched.h>
-#include <linux/ftape.h>
-#include <asm/system.h>
-#include <asm/io.h>
-
-#include "tracing.h"
-#include "calibr.h"
-#include "fdc-io.h"
-
-#undef DEBUG
-
-unsigned timestamp(void)
-{
-	unsigned count;
-	unsigned long flags;
-
-	save_flags(flags);
-	cli();
-	outb_p(0x00, 0x43);	/* latch the count ASAP */
-	count = inb_p(0x40);	/* read the latched count */
-	count |= inb(0x40) << 8;
-	restore_flags(flags);
-	return (LATCH - count);	/* normal: downcounter */
-}
-
-int timediff(int t0, int t1)
-{
-	/*  Calculate difference in usec for timestamp results t0 & t1.
-	 *  Note that the maximum timespan allowed is 1/HZ or we'll lose ticks!
-	 */
-	if (t1 < t0) {
-		t1 += LATCH;
-	}
-	return (1000 * (t1 - t0)) / ((CLOCK_TICK_RATE + 500) / 1000);
-}
-
-/*      To get an indication of the I/O performance,
- *      measure the duration of the inb() function.
- */
-void time_inb(void)
-{
-	TRACE_FUN(8, "time_inb");
-	int i;
-	int t0, t1;
-	unsigned long flags;
-	int status;
-
-	save_flags(flags);
-	cli();
-	t0 = timestamp();
-	for (i = 0; i < 1000; ++i) {
-		status = inb(fdc.msr);
-	}
-	t1 = timestamp();
-	restore_flags(flags);
-	if (t1 - t0 <= 0) {
-		t1 += LATCH;
-	}
-	TRACEx1(4, "inb() duration: %d nsec", timediff(t0, t1));
-	TRACE_EXIT;
-}
-
-/*  Haven't studied on why, but there sometimes is a problem
- *  with the tick timer readout. The two bytes get swapped.
- *  This hack solves that problem by doing one extra input.
- */
-void fix_clock(void)
-{
-	TRACE_FUN(8, "fix_clock");
-	int t;
-	int i;
-
-	for (i = 0; i < 1000; ++i) {
-		t = timestamp();
-		if (t < 0) {
-			inb_p(0x40);	/* get in sync again */
-			TRACE(2, "clock counter fixed");
-			break;
-		}
-	}
-	TRACE_EXIT;
-}
-
-/*
- *      Input:  function taking int count as parameter.
- *              pointers to calculated calibration variables.
- */
-int calibrate(char *name, void (*fun) (int), int *calibr_count, int *calibr_time)
-{
-	TRACE_FUN(5, "calibrate");
-	static int first_time = 1;
-	int i;
-	int old_tc = 0;
-	int old_count = 1;
-	int old_time = 1;
-
-	if (first_time) {	/* get idea of I/O performance */
-		fix_clock();
-		time_inb();
-		first_time = 0;
-	}
-	/*    value of timeout must be set so that on very slow systems
-	 *    it will give a time less than one jiffy, and on
-	 *    very fast systems it'll give reasonable precision.
-	 */
-
-	*calibr_count = 10;
-	for (i = 0; i < 15; ++i) {
-		int t0, t1;
-		unsigned long flags;
-		int once;
-		int multiple;
-		int tc;
-
-		*calibr_time = *calibr_count;	/* set TC to 1 */
-		fun(0);		/* dummy, get code into cache */
-		save_flags(flags);
-		cli();
-		t0 = timestamp();
-		fun(0);		/* overhead + one test */
-		t1 = timestamp();
-		if (t1 < t0) {
-			t1 += LATCH;
-		}
-		once = t1 - t0;
-		t0 = timestamp();
-		fun(*calibr_count);	/* overhead + multiple tests */
-		t1 = timestamp();
-		if (t1 < t0) {
-			t1 += LATCH;
-		}
-		multiple = t1 - t0;
-		restore_flags(flags);
-		*calibr_time = (10000 * (multiple - once)) / (CLOCK_TICK_RATE / 100);
-		--*calibr_count;	/* because delta corresponds to this count */
-		tc = (1000 * *calibr_time) / *calibr_count;
-		TRACEx4(8, "once:%4d us,%5d times:%6d us, TC:%5d ns",
-			(10000 * once) / (CLOCK_TICK_RATE / 100),
-			*calibr_count,
-			(10000 * multiple) / (CLOCK_TICK_RATE / 100),
-			tc);
-		/*
-		 * increase the count until the resulting time nears 2/HZ,
-		 * then the tc will drop sharply because we lose LATCH counts.
-		 */
-		if (tc <= old_tc / 2) {
-			*calibr_time = old_time;
-			*calibr_count = old_count;
-			break;
-		}
-		old_tc = tc;
-		old_count = *calibr_count;
-		old_time = *calibr_time;
-		*calibr_count *= 2;
-	}
-	TRACEx3(4, "TC for `%s()' = %d nsec (at %d counts)",
-	     name, (1000 * *calibr_time) / *calibr_count, *calibr_count);
-	TRACE_EXIT;
-	return 0;
-}