pic.c

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#include <sys/types.h>
#include <sys/io.h>
#include <stdio.h>
#include <assert.h>
#include <stdarg.h>

#include <pic.h>

#define CLOCK 1193180

enum port_t {
        PIC_FIRST_COMMAND               = 0x20,
        PIC_FIRST_INTERRUPT_MASK        = 0x21,

        PIC_SECOND_COMMAND              = 0xA0,
        PIC_SECOND_INTERRUPT_MASK       = 0xA1,

        TIMER_COUNTER_DIVISOR           = 0x40,
        TIMER_MODE_CONTROL              = 0x43,

        CG_6845_INDEX                   = 0x3D4,
        CG_6845_DATA                    = 0x3D5,
        CG_6845_MODE_CONTROL            = 0x3D8,
        CG_6845_COLOR_SELECT_PALETTE    = 0x3D9,
        CG_6845_STATUS                  = 0x3DA,
        CG_6845_CLEAR_LIGHT_PEN_LATCH   = 0x3DB,
        CG_6845_PRESET_LIGHT_PEN_LATCH  = 0x3DC,
        CG_6845_CRT_CPU_PAGE            = 0x3DF,
};

void pic_init(void)
{
        outb(PIC_FIRST_COMMAND, 0x11);
        outb(PIC_FIRST_INTERRUPT_MASK, 0x20);
        outb(PIC_FIRST_INTERRUPT_MASK, 0x04);
        outb(PIC_FIRST_INTERRUPT_MASK, 0x01);
        outb(PIC_FIRST_INTERRUPT_MASK, 0xB8);

        outb(PIC_SECOND_COMMAND, 0x11);
        outb(PIC_SECOND_INTERRUPT_MASK, 0x28);
        outb(PIC_SECOND_INTERRUPT_MASK, 0x02);
        outb(PIC_SECOND_INTERRUPT_MASK, 0x01);
        outb(PIC_SECOND_INTERRUPT_MASK, 0xFF);
}

void timer_init(unsigned long frequency)
{
        unsigned long divisor = CLOCK / frequency;
        outb(TIMER_MODE_CONTROL, 0x34);
        outb(TIMER_COUNTER_DIVISOR, divisor & 0xff);
        outb(TIMER_COUNTER_DIVISOR, (divisor >> 8) & 0xff);
}

/* End of a file */