include/setup.sh

1 files changed, 45 insertions, 0 deletions

diff --git a/include/07.pit/timer.c b/include/07.pit/timer.c
new file mode 100644
index 0000000..390e512
--- /dev/null
+++ b/include/07.pit/timer.c
@@ -0,0 +1,45 @@
+#include<types.h>
+#include<asm.h>
+#include<stdio.h>
+
+void add_idt_entry(size_t num,uint32_t offset);
+
+uint32_t tick=0;
+const uint32_t TICKS_PER_SECOND=50;
+extern uint32_t time;
+uint32_t time=0;
+
+void timer_handler()
+{
+    tick++;
+    if(tick==TICKS_PER_SECOND)
+    {
+        //printf("%d seconds passed\n",time);
+        tick=0;
+        time++;
+    }
+
+    ioport_out(0x20, 0x20);
+    ioport_out(0xa0,0x20);
+}
+
+void init_timer(uint32_t frequency)
+{
+    // Firstly, register our timer callback.
+
+    // The value we send to the PIT is the value to divide it's input clock
+    // (1193180 Hz) by, to get our required frequency. Important to note is
+    // that the divisor must be small enough to fit into 16-bits.
+    uint32_t divisor = 1193180 / frequency;
+
+    // Send the command byte.
+    ioport_out(0x43, 0x36);
+
+    // Divisor has to be sent byte-wise, so split here into upper/lower bytes.
+    uint8_t l = (uint8_t)(divisor & 0xFF);
+    uint8_t h = (uint8_t)( (divisor>>8) & 0xFF );
+
+    // Send the frequency divisor.
+    ioport_out(0x40, l);
+    ioport_out(0x40, h);
+}