119 lines
3.1 KiB
C
119 lines
3.1 KiB
C
/*-
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* Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <stand.h>
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#include <btxv86.h>
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#include "bootstrap.h"
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#include "libi386.h"
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time_t getsecs(void);
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static int bios_seconds(void);
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/*
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* Return the BIOS time-of-day value.
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*
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* XXX uses undocumented BCD support from libstand.
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*/
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static int
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bios_seconds(void)
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{
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int hr, minute, sec;
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v86.ctl = 0;
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v86.addr = 0x1a; /* int 0x1a, function 2 */
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v86.eax = 0x0200;
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v86int();
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hr = bcd2bin((v86.ecx & 0xff00) >> 8); /* hour in %ch */
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minute = bcd2bin(v86.ecx & 0xff); /* minute in %cl */
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sec = bcd2bin((v86.edx & 0xff00) >> 8); /* second in %dh */
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return (hr * 3600 + minute * 60 + sec);
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}
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/*
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* Return the time in seconds since the beginning of the day.
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*
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* Some BIOSes (notably qemu) don't correctly read the RTC
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* registers in an atomic way, sometimes returning bogus values.
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* Therefore we "debounce" the reading by accepting it only when
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* we got 8 identical values in succession.
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*
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* If we pass midnight, don't wrap back to 0.
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*/
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time_t
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time(time_t *t)
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{
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static time_t lasttime;
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time_t now, check;
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int same, try;
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same = try = 0;
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check = bios_seconds();
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do {
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now = check;
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check = bios_seconds();
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if (check != now)
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same = 0;
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} while (++same < 8 && ++try < 1000);
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if (now < lasttime)
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now += 24 * 3600;
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lasttime = now;
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if (t != NULL)
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*t = now;
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return(now);
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}
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time_t
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getsecs(void)
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{
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time_t n = 0;
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time(&n);
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return n;
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}
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/*
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* Use the BIOS Wait function to pause for (period) microseconds.
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*
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* Resolution of this function is variable, but typically around
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* 1ms.
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*/
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void
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delay(int period)
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{
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v86.ctl = 0;
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v86.addr = 0x15; /* int 0x15, function 0x86 */
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v86.eax = 0x8600;
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v86.ecx = period >> 16;
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v86.edx = period & 0xffff;
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v86int();
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}
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