Create pic.c

Implementation for pic.h

kernel/pic.h

@@ -0,0 +1,25 @@
+#ifndef PIC_H
+#define PIC_H
+
+#include <stdint.h>
+
+/* I/O Ports for the PICs */
+#define PIC1_COMMAND 0x20
+#define PIC1_DATA    0x21
+#define PIC2_COMMAND 0xA0
+#define PIC2_DATA    0xA1
+
+/* PIC Commands */
+#define PIC_EOI      0x20  /* End of Interrupt */
+
+/* Offset vectors for remapping */
+#define PIC1_OFFSET  0x20
+#define PIC2_OFFSET  0x28
+
+void pic_init(void);
+void pic_send_eoi(uint8_t irq);
+void pic_mask(uint8_t irq);
+void pic_unmask(uint8_t irq);
+void pic_disable(void);
+
+#endif

pic.c

@@ -0,0 +1,76 @@
+#include "pic.h"
+#include "io.h"
+
+/* Small delay for older hardware bus timing */
+static inline void io_wait(void) {
+    outb(0x80, 0); 
+}
+
+void pic_init(void) {
+    uint8_t a1, a2;
+
+    // Save current masks
+    a1 = inb(PIC1_DATA);
+    a2 = inb(PIC2_DATA);
+
+    // ICW1: Start initialization in cascade mode
+    outb(PIC1_COMMAND, 0x11);
+    io_wait();
+    outb(PIC2_COMMAND, 0x11);
+    io_wait();
+
+    // ICW2: Master PIC vector offset
+    outb(PIC1_DATA, PIC1_OFFSET);
+    io_wait();
+    // ICW2: Slave PIC vector offset
+    outb(PIC2_DATA, PIC2_OFFSET);
+    io_wait();
+
+    // ICW3: Tell Master there is a slave at IRQ2 (0000 0100)
+    outb(PIC1_DATA, 4);
+    io_wait();
+    // ICW3: Tell Slave its cascade identity (0000 0010)
+    outb(PIC2_DATA, 2);
+    io_wait();
+
+    // ICW4: Set 8086/88 mode
+    outb(PIC1_DATA, 0x01);
+    io_wait();
+    outb(PIC2_DATA, 0x01);
+    io_wait();
+
+    // Restore masks (or disable all to start clean)
+    outb(PIC1_DATA, 0xFB); // Keep IRQ2 (cascade) open
+    outb(PIC2_DATA, 0xFF);
+}
+
+void pic_send_eoi(uint8_t irq) {
+    if (irq >= 8) {
+        outb(PIC2_COMMAND, PIC_EOI);
+    }
+    outb(PIC1_COMMAND, PIC_EOI);
+}
+
+void pic_unmask(uint8_t irq) {
+    uint16_t port;
+    if (irq < 8) {
+        port = PIC1_DATA;
+    } else {
+        port = PIC2_DATA;
+        irq -= 8;
+    }
+    uint8_t value = inb(port) & ~(1 << irq);
+    outb(port, value);
+}
+
+void pic_mask(uint8_t irq) {
+    uint16_t port;
+    if (irq < 8) {
+        port = PIC1_DATA;
+    } else {
+        port = PIC2_DATA;
+        irq -= 8;
+    }
+    uint8_t value = inb(port) | (1 << irq);
+    outb(port, value);
+}