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
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--- /dev/null
+++ b/stand/i386/libi386/time.c
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+/*-
+ * 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();
+}