# HG changeset patch
# User John Tsiombikas <nuclear@member.fsf.org>
# Date 1307491362 -10800
# Node ID 373a9f50b4e6cbe81bf9d1d466185ff398a8e82f
# Parent  3ed041d07ae13f95883e5ba43ee18bb58ff27b50
8254 timer code

diff -r 3ed041d07ae1 -r 373a9f50b4e6 src/config.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/config.h	Wed Jun 08 03:02:42 2011 +0300
@@ -0,0 +1,7 @@
+#ifndef _CONFIG_H_
+#define _CONFIG_H_
+
+/* frequency of generated timer ticks in hertz */
+#define TICK_FREQ_HZ		250
+
+#endif	/* _CONFIG_H_ */
diff -r 3ed041d07ae1 -r 373a9f50b4e6 src/main.c
--- a/src/main.c	Fri May 27 13:08:23 2011 +0300
+++ b/src/main.c	Wed Jun 08 03:02:42 2011 +0300
@@ -5,11 +5,10 @@
 #include "asmops.h"
 #include "segm.h"
 #include "intr.h"
+#include "timer.h"
 #include "mem.h"
 #include "vm.h"
 
-static void do_nothing();
-
 /* special keys */
 enum {
 	LALT, RALT,
@@ -55,8 +54,7 @@
 	init_segm();
 	init_intr();
 
-	/* silence the blasted timer interrupt */
-	interrupt(32, do_nothing);
+	init_timer();
 
 	/* initialize the physical memory manager */
 	init_mem(mbinf);
@@ -66,27 +64,6 @@
 	/* initialization complete, enable interrupts */
 	enable_intr();
 
-	dbg_print_vm(MEM_USER);
-	dbg_print_vm(MEM_KERNEL);
-
-	{
-		void *foo, *bar, *xyzzy, *koko, *lala;
-
-		foo = malloc(128);
-		bar = malloc(32 * 1024);
-		xyzzy = malloc(8000);
-
-		free(bar);
-
-		koko = malloc(700);
-		lala = malloc(6 * 1024 * 1024);
-
-		free(xyzzy);
-		free(foo);
-		free(koko);
-		free(lala);
-	}
-
 	for(;;) {
 		char c, keypress;
 		do {
@@ -98,7 +75,3 @@
 		}
 	}
 }
-
-static void do_nothing()
-{
-}
diff -r 3ed041d07ae1 -r 373a9f50b4e6 src/timer.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/timer.c	Wed Jun 08 03:02:42 2011 +0300
@@ -0,0 +1,78 @@
+#include <stdio.h>
+#include "intr.h"
+#include "asmops.h"
+#include "config.h"
+
+/* frequency of the oscillator driving the 8254 timer */
+#define OSC_FREQ_HZ		1193182
+
+/* macro to divide and round to the nearest integer */
+#define DIV_ROUND(a, b) ((a) / (b) + ((a) % (b)) / ((b) / 2))
+
+/* I/O ports connected to the 8254 */
+#define PORT_DATA0	0x40
+#define PORT_DATA1	0x41
+#define PORT_DATA2	0x42
+#define PORT_CMD	0x43
+
+/* command bits */
+#define CMD_CHAN0			0
+#define CMD_CHAN1			(1 << 6)
+#define CMD_CHAN2			(2 << 6)
+#define CMD_RDBACK			(3 << 6)
+
+#define CMD_LATCH			0
+#define CMD_ACCESS_LOW		(1 << 4)
+#define CMD_ACCESS_HIGH		(2 << 4)
+#define CMD_ACCESS_BOTH		(3 << 4)
+
+#define CMD_OP_INT_TERM		0
+#define CMD_OP_ONESHOT		(1 << 1)
+#define CMD_OP_RATE			(2 << 1)
+#define CMD_OP_SQWAVE		(3 << 1)
+#define CMD_OP_SOFT_STROBE	(4 << 1)
+#define CMD_OP_HW_STROBE	(5 << 1)
+
+#define CMD_MODE_BIN		0
+#define CMD_MODE_BCD		1
+
+
+static void intr_handler();
+
+static unsigned long nticks;
+
+
+void init_timer(void)
+{
+	/* calculate the reset count: round(osc / freq) */
+	int reset_count = DIV_ROUND(OSC_FREQ_HZ, TICK_FREQ_HZ);
+
+	/* set the mode to square wave for channel 0, both low
+	 * and high reset count bytes will follow...
+	 */
+	outb(CMD_CHAN0 | CMD_ACCESS_BOTH | CMD_OP_SQWAVE, PORT_CMD);
+
+	/* write the low and high bytes of the reset count to the
+	 * port for channel 0
+	 */
+	outb(reset_count & 0xff, PORT_DATA0);
+	outb((reset_count >> 8) & 0xff, PORT_DATA0);
+
+	nticks = 0;
+
+	/* set the timer interrupt handler */
+	interrupt(32, intr_handler);
+}
+
+/* This will be called by the interrupt dispatcher approximately
+ * every 1/250th of a second, so it must be extremely fast.
+ * For now, just increasing a tick counter will suffice.
+ */
+static void intr_handler()
+{
+	nticks++;
+
+	if(nticks % TICK_FREQ_HZ == 0) {
+		printf("%lu sec\n", nticks / TICK_FREQ_HZ);
+	}
+}
diff -r 3ed041d07ae1 -r 373a9f50b4e6 src/timer.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/timer.h	Wed Jun 08 03:02:42 2011 +0300
@@ -0,0 +1,8 @@
+#ifndef _TIMER_H_
+#define _TIMER_H_
+
+unsigned long nticks;
+
+void init_timer(void);
+
+#endif	/* _TIMER_H_ */
diff -r 3ed041d07ae1 -r 373a9f50b4e6 src/vm.c
--- a/src/vm.c	Fri May 27 13:08:23 2011 +0300
+++ b/src/vm.c	Wed Jun 08 03:02:42 2011 +0300
@@ -259,7 +259,7 @@
 
 void pgfree(int start, int num)
 {
-	int i, area, end, intr_state;
+	int i, area, intr_state;
 	struct page_range *node, *new, *prev, *next;
 
 	intr_state = get_intr_state();
@@ -276,7 +276,7 @@
 		panic("pgfree: can't allocate new page_range node to add the freed pages\n");
 	}
 	new->start = start;
-	end = new->end = start + num;
+	new->end = start + num;
 
 	area = PAGE_TO_ADDR(start) >= KMEM_START ? MEM_KERNEL : MEM_USER;