Preliminary PIT added, needs IDT install

src/pit.c

+#include "pit.h"
+#include "pic.h"
+
+static volatile uint32_t _pit_ticks = 0;
+static bool _pit_is_init = false;
+
+void pit_irq()
+{
+    asm volatile ("add %esp, 12; pushad");
+    _pit_ticks++;
+    //TODO: NEED TO SEND DONE MESSAGE BACK
+    asm volatile("popad; iretd");
+}
+
+void pit_command(uint8_t cmd)
+{
+    outb(PIC_REG_COMD, cmd);
+}
+
+void pit_write(uint16_t data, uint8_t counter)
+{
+    uint16_t port= (counter == PIT_OCW_CONT_0) ? PIT_REG_CONT_0 :
+	((counter == PIT_OCW_CONT_1) ? PIT_REG_CONT_1 : PIT_REG_CONT_2);
+    outb(port, (uint8_t)data);
+}
+
+uint8_t pit_read(uint16_t counter)
+{
+    uint16_t port= (counter == PIT_OCW_CONT_0) ? PIT_REG_CONT_0 :
+	((counter == PIT_OCW_CONT_1) ? PIT_REG_CONT_1 : PIT_REG_CONT_2);
+    return inb(port);
+}
+
+uint32_t pit_set_tick(uint32_t i)
+{
+    uint32_t ret = _pit_ticks;
+    _pit_ticks = i;
+    return ret;
+}
+
+uint32_t pit_get_tick()
+{
+    return _pit_ticks;
+}
+
+void pit_start_counter(uint32_t frequency, uint8_t counter, uint8_t mode)
+{
+    if(freq == 0)
+    {
+	return;
+    }
+
+    uint16_t div = (uint16_t)(1193181 / (uint16_t)freq);
+
+    uint8_t ocw = 0;
+    ocw = (ocw & ~PIT_OCW_MODE) | mode;
+    ocw = (ocw & ~PIT_OCW_RL) | PIT_OCW_RL_DATA;
+    ocw = (ocw & ~PIT_OCW_CONT) | counter;
+    pit_command(ocw);
+
+    pit_write(div & 0xFF, 0);
+    pit_write((div >> 8)& 0xFF, 0);
+    
+    _pit_ticks = 0;
+}
+
+void pit_init();
+{
+    //TODO: NEED TO SET INT 32 TO PIT IRQ HANDLER
+    _pit_is_init = true;
+}
+
+bool pit_is_init()
+{
+    return _pit_is_init;
+}

src/pit.h

+#ifndef _PIT_INC
+#define _PIT_INC
+
+#include <stdint.h>
+
+//OCW masks
+#define PIT_OCW_BINC 0x01
+#define PIT_OCW_MODE 0x0E
+#define PIT_OCW_RL   0x30
+#define PIT_OCW_CONT 0xC0
+
+//OCW control bits
+#define PIT_OCW_BINC_BIN 0x0
+#define PIT_OCW_BINC_BCD 0x1
+
+#define PIT_OCW_MODE_TERMCNT 0x0
+#define PIT_OCW_MODE_ONESHOT 0x2
+#define PIT_OCW_MODE_RATEGEN 0x4
+#define PIT_OCW_MODE_SQWVGEN 0x6
+#define PIT_OCW_MODE_SOFTTRG 0x8
+#define PIT_OCW_MODE_HARDTRG 0xA
+
+#define PIT_OCW_RL_LATH 0x00
+#define PIT_OCW_RL_LSB  0x10
+#define PIT_OCW_RL_MSB  0x20
+#define PIT_OCW_RL_DATA 0x30
+
+#define PIT_OCW_CONT_0 0x00
+#define PIT_OCW_CONT_1 0x40
+#define PIT_OCW_CONT_2 0x80
+
+#define PIT_REG_CONT_0 0x40
+#define PIT_REG_CONT_1 0x41
+#define PIT_REG_CONT_2 0x42
+#define PIT_REG_COMD 0x43
+
+void pit_command(uint8_t cmd);
+void pit_write(uint16_t data, uint8_t counter);
+uint8_t pit_read(uint16_t counter);
+uint32_t pit_set_tick(uint32_t i);
+uint32_t pit_get_tick();
+void pit_start_counter(uint32_t frequency, uint8_t counter, uint8_t mode);
+void pit_init();
+bool pit_is_init();
+
+#endif