ReKernel/pic.c at main · HFerrahoglu/ReKernel · GitHub

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#include "pic.h"

void pic_remap(void) {
    /* Save masks */
    uint8_t m1 = inb(PIC1_DATA), m2 = inb(PIC2_DATA);

    /* ICW1: start initialisation */
    outb(PIC1_CMD, 0x11); io_wait();
    outb(PIC2_CMD, 0x11); io_wait();
    /* ICW2: vector offsets */
    outb(PIC1_DATA, 0x20); io_wait();  /* IRQ0  → int 32 */
    outb(PIC2_DATA, 0x28); io_wait();  /* IRQ8  → int 40 */
    /* ICW3: cascade wiring */
    outb(PIC1_DATA, 0x04); io_wait();  /* PIC1 has slave on IRQ2 */
    outb(PIC2_DATA, 0x02); io_wait();  /* PIC2 cascade identity = 2 */
    /* ICW4: 8086 mode */
    outb(PIC1_DATA, 0x01); io_wait();
    outb(PIC2_DATA, 0x01); io_wait();
    /* Mask ALL IRQs — drivers unmask only what they need */
    (void)m1; (void)m2;
    outb(PIC1_DATA, 0xFF);
    outb(PIC2_DATA, 0xFF);
}

void pic_send_eoi(uint8_t irq) {
    if (irq >= 8) outb(PIC2_CMD, PIC_EOI);
    outb(PIC1_CMD, PIC_EOI);
}

void pic_mask_irq(uint8_t irq) {
    uint16_t port = (irq < 8) ? PIC1_DATA : PIC2_DATA;
    uint8_t  bit  = (irq < 8) ? irq : (uint8_t)(irq - 8);
    outb(port, inb(port) | (uint8_t)(1 << bit));
}

void pic_unmask_irq(uint8_t irq) {
    uint16_t port = (irq < 8) ? PIC1_DATA : PIC2_DATA;
    uint8_t  bit  = (irq < 8) ? irq : (uint8_t)(irq - 8);
    outb(port, inb(port) & (uint8_t)~(1 << bit));
}