--- Net2/arch/i386/isa/clock.c	2018/04/24 18:04:01	1.1
+++ Net2/arch/i386/isa/clock.c	2018/04/24 18:11:58	1.1.1.2
@@ -34,29 +34,47 @@
  * SUCH DAMAGE.
  *
  *	@(#)clock.c	7.2 (Berkeley) 5/12/91
+ *
+ * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
+ * --------------------         -----   ----------------------
+ * CURRENT PATCH LEVEL:         3       00082
+ * --------------------         -----   ----------------------
+ *
+ * 14 Aug 92	Arne Henrik Juul	Added code in the kernel to
+ *					allow for DST in the BIOS.
+ * 17 Jan 93	Bruce Evans		Fixed leap year and second
+ *					calculations
+ * 01 Feb 93	Julian Elischer		Added code to for the cpu
+ *					speed independent spinwait()
+ *					function, (used by scsi and others)
  */
 
 /*
  * Primitive clock interrupt routines.
  */
 #include "param.h"
+#include "systm.h"
 #include "time.h"
 #include "kernel.h"
 #include "machine/segments.h"
 #include "i386/isa/icu.h"
 #include "i386/isa/isa.h"
 #include "i386/isa/rtc.h"
+#include "i386/isa/timerreg.h"
 
 #define DAYST 119
 #define DAYEN 303
+#define XTALSPEED 1193182
 
 startrtclock() {
 	int s;
 
+	findcpuspeed();		/* use the clock (while it's free)
+					to find the cpu speed */
 	/* initialize 8253 clock */
-	outb (IO_TIMER1+3, 0x36);
-	outb (IO_TIMER1, 1193182/hz);
-	outb (IO_TIMER1, (1193182/hz)/256);
+	outb(TIMER_MODE, TIMER_SEL0|TIMER_RATEGEN|TIMER_16BIT);
+	outb (IO_TIMER1, XTALSPEED/hz);
+	outb (IO_TIMER1, (XTALSPEED/hz)/256);
 
 	/* initialize brain-dead battery powered clock */
 	outb (IO_RTC, RTC_STATUSA);
@@ -71,6 +89,32 @@ startrtclock() {
 	outb (IO_RTC+1, 0);
 }
 
+unsigned int delaycount;	/* calibrated loop variable (1 millisecond) */
+
+#define FIRST_GUESS	0x2000
+findcpuspeed()
+{
+	unsigned char low;
+	unsigned int remainder;
+
+	/* Put counter in count down mode */
+	outb(IO_TIMER1+3, 0x34);
+	outb(IO_TIMER1, 0xff);
+	outb(IO_TIMER1, 0xff);
+	delaycount = FIRST_GUESS;
+	spinwait(1);
+	/* Read the value left in the counter */
+	low 	= inb(IO_TIMER1);	/* least siginifcant */
+	remainder = inb(IO_TIMER1);	/* most significant */
+	remainder = (remainder<<8) + low ;
+	/* Formula for delaycount is :
+	 *  (loopcount * timer clock speed)/ (counter ticks * 1000)
+	 */
+	delaycount = (FIRST_GUESS * (XTALSPEED/1000)) / (0xffff-remainder);
+}
+
+
+
 /* convert 2 digit BCD number */
 bcd(i)
 int i;
@@ -86,8 +130,8 @@ int y;
 	int i;
 	unsigned long ret;
 
-	ret = 0; y = y - 70;
-	for(i=0;i<y;i++) {
+	ret = 0;
+	for(i = 1970; i < y; i++) {
 		if (i % 4) ret += 365*24*60*60;
 		else ret += 366*24*60*60;
 	}
@@ -137,25 +181,24 @@ inittodr(base)
 	while ((sa&RTCSA_TUP) == RTCSA_TUP)
 		sa = rtcin(RTC_STATUSA);
 
-	sec = bcd(rtcin(RTC_YEAR));
-	leap = !(sec % 4); sec += ytos(sec); /* year    */
+	sec = bcd(rtcin(RTC_YEAR)) + 1900;
+	if (sec < 1970)
+		sec += 100;
+	leap = !(sec % 4); sec = ytos(sec); /* year    */
 	yd = mtos(bcd(rtcin(RTC_MONTH)),leap); sec += yd;	/* month   */
 	t = (bcd(rtcin(RTC_DAY))-1) * 24*60*60; sec += t; yd += t; /* date    */
 	day_week = rtcin(RTC_WDAY);				/* day     */
 	sec += bcd(rtcin(RTC_HRS)) * 60*60;			/* hour    */
 	sec += bcd(rtcin(RTC_MIN)) * 60;			/* minutes */
 	sec += bcd(rtcin(RTC_SEC));				/* seconds */
-	sec -= 24*60*60; /* XXX why ??? */
 
-#ifdef notdef
 	/* XXX off by one? Need to calculate DST on SUNDAY */
 	/* Perhaps we should have the RTC hold GMT time to save */
 	/* us the bother of converting. */
-	yd = yd / 24*60*60;
+	yd = yd / (24*60*60);
 	if ((yd >= DAYST) && ( yd <= DAYEN)) {
 		sec -= 60*60;
 	}
-#endif
 	sec += tz.tz_minuteswest * 60;
 
 	time.tv_sec = sec;
@@ -204,3 +247,17 @@ enablertclock() {
 	setidt(ICU_OFFSET+0, &V(clk), SDT_SYS386IGT, SEL_KPL);
 	splnone();
 }
+
+
+
+
+spinwait(millisecs)
+int millisecs;		/* number of milliseconds to delay */
+{
+	int i, j;
+
+	for (i=0;i<millisecs;i++)
+		for (j=0;j<delaycount;j++)
+			;
+}
+