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Diffstat (limited to 'stand/i386/libi386/time.c')
-rw-r--r-- | stand/i386/libi386/time.c | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/stand/i386/libi386/time.c b/stand/i386/libi386/time.c new file mode 100644 index 000000000000..7636ace5ff94 --- /dev/null +++ b/stand/i386/libi386/time.c @@ -0,0 +1,118 @@ +/*- + * Copyright (c) 1998 Michael Smith <msmith@freebsd.org> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <stand.h> +#include <btxv86.h> +#include "bootstrap.h" +#include "libi386.h" + +time_t getsecs(void); +static int bios_seconds(void); + +/* + * Return the BIOS time-of-day value. + * + * XXX uses undocumented BCD support from libstand. + */ +static int +bios_seconds(void) +{ + int hr, minute, sec; + + v86.ctl = 0; + v86.addr = 0x1a; /* int 0x1a, function 2 */ + v86.eax = 0x0200; + v86int(); + + hr = bcd2bin((v86.ecx & 0xff00) >> 8); /* hour in %ch */ + minute = bcd2bin(v86.ecx & 0xff); /* minute in %cl */ + sec = bcd2bin((v86.edx & 0xff00) >> 8); /* second in %dh */ + + return (hr * 3600 + minute * 60 + sec); +} + +/* + * Return the time in seconds since the beginning of the day. + * + * Some BIOSes (notably qemu) don't correctly read the RTC + * registers in an atomic way, sometimes returning bogus values. + * Therefore we "debounce" the reading by accepting it only when + * we got 8 identical values in succession. + * + * If we pass midnight, don't wrap back to 0. + */ +time_t +time(time_t *t) +{ + static time_t lasttime; + time_t now, check; + int same, try; + + same = try = 0; + check = bios_seconds(); + do { + now = check; + check = bios_seconds(); + if (check != now) + same = 0; + } while (++same < 8 && ++try < 1000); + + if (now < lasttime) + now += 24 * 3600; + lasttime = now; + + if (t != NULL) + *t = now; + return(now); +} + +time_t +getsecs(void) +{ + time_t n = 0; + time(&n); + return n; +} + +/* + * Use the BIOS Wait function to pause for (period) microseconds. + * + * Resolution of this function is variable, but typically around + * 1ms. + */ +void +delay(int period) +{ + v86.ctl = 0; + v86.addr = 0x15; /* int 0x15, function 0x86 */ + v86.eax = 0x8600; + v86.ecx = period >> 16; + v86.edx = period & 0xffff; + v86int(); +} |