From 684fc27f6389f44102b5a3b31f62badc35a9a9ce Mon Sep 17 00:00:00 2001
From: Ben Burwell <ben@benburwell.com>
Date: Wed, 1 Apr 2015 20:32:27 -0400
Subject: as of 2013-12-04

---
 clock.c | 141 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 141 insertions(+)
 create mode 100644 clock.c

(limited to 'clock.c')

diff --git a/clock.c b/clock.c
new file mode 100644
index 0000000..f828307
--- /dev/null
+++ b/clock.c
@@ -0,0 +1,141 @@
+/*
+ * Clock support for MPX-OS
+ * Ben Burwell & Averill Morash
+ * CSI350 - Fall 2013
+ */
+
+#include <dos.h>
+#include "mpx.h"
+
+void interrupt (*vect08)();
+unsigned long clock;         /* The clock counter       */
+
+/*
+ * Set up MXP clock
+ */
+void clock_open() {
+	unsigned char imr;
+
+	disable();
+	/* set up interrupt vector for timer interrupts */
+	vect08 = getvect(0x08);
+	setvect(0x08,&clock_int);
+
+	// set the timer mode
+	outportb(CMR, 0x36);
+	outportb(0x40, 0);
+	outportb(0x40, 0);
+
+	// set the count clock
+	clock = 0L;
+
+	// enable timer interrupts
+	imr = inportb(IMR);       // Get current IMR
+	imr = imr & CLOCK_ENABLE; // Clear timer bit
+	outportb(IMR, imr);       // Set new IMR
+
+	enable();
+}
+
+/*
+ * Restore the MS DOS clock
+ */
+void clock_close() {
+  disable();
+  setvect(0x08,vect08);
+  enable();
+}
+
+void interrupt clock_int() {
+  disable();
+  // if it's been 24 hours, reset clock to 0
+  if (clock >= 1572462L) {
+	clock = 0L;
+  } else {
+	clock++;
+  }
+  outportb(0x20, 0x20);
+  enable();
+}
+
+void stop_clock() {
+  unsigned char imr;
+  disable();
+
+  imr = inportb(IMR);        // Get the old imr
+  imr = imr | CLOCK_DISABLE; // Disable timer interrupts
+  outportb(IMR, imr);        // Set the new imr
+
+  enable();
+}
+
+/*
+ * Enables the timer interrupt
+ */
+void start_clock() {
+  unsigned char imr;
+  disable();
+
+  imr = inportb(IMR);        // Get the old imr
+  imr = imr & CLOCK_ENABLE;  // Enable timer interrupts
+  outportb(IMR, imr);        // Set the new imr
+
+  enable();
+}
+
+/*
+ * Sets the value of the clock
+ */
+int set_clock(int hr, int m, int s) {
+  unsigned long ticks;
+
+  // Validate input
+  if (hr > 23 || hr < 0 || m > 59 || m < 0 || s > 59 || s < 0) {
+	return -1;
+  }
+
+  // set clock
+  ticks = 0L;
+  ticks  = ((unsigned long)hr * 3600L * 91L / 5L);
+  ticks += ((unsigned long)m  * 60L   * 91L / 5L);
+  ticks += ((unsigned long)s          * 91L / 5L);
+
+  disable();
+  clock = ticks;
+  enable();
+
+  return 0;
+}
+
+/*
+ * Gets the value of the clock
+ */
+void read_clock(int *hr, int *m, int *s) {
+  unsigned long ticks;
+  long total_seconds = 0L;
+  int l_hr = 0;
+  int l_m = 0; //local vars for hr, m
+
+  disable();
+  ticks = clock;
+  enable();
+
+  total_seconds = ticks * 10L;
+  total_seconds = total_seconds / 182L;
+
+  //count the whole hours
+  while (total_seconds >= 3600L) {
+	l_hr++;
+	total_seconds = total_seconds - 3600L;
+  }
+
+  //count the whole minutes
+  while (total_seconds >= 60L) {
+	l_m++;
+	total_seconds = total_seconds - 60L;
+  }
+
+  *hr = l_hr;
+  *m = l_m;
+  *s = total_seconds;
+}
\ No newline at end of file
-- 
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