Got IDT & ISRs working!

2025-03-21 14:09:15 +01:00
parent 05c8ee8f67
commit c3f8d7d8f2
9 changed files with 322 additions and 2 deletions
@@ -0,0 +1,105 @@
+#include <syscall.h>
+#include <kernel.h>
+#include <string.h>
+#include <system.h>
+#include <idt.h>
+#include <isr.h>
+
+isr_handlerPtr irqHandlers[16];
+
+const char* exceptions[] = {
+	"Division By Zero",
+	"Debug",
+	"Non Maskable Interrupt",
+	"Breakpoint",
+	"Into Detected Overflow",
+	"Out of Bounds",
+	"Invalid Opcode",
+	"No Coprocessor",
+	"Double Fault",
+	"Coprocessor Segment Overrun",
+	"Bad TSS",
+	"Segment Not Present",
+	"Stack Fault",
+	"General Protection Fault",
+	"Page Fault",
+	"Unknown Interrupt",
+	"Coprocessor Fault",
+	"Alignment Check",
+	"Machine Check",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved"
+};
+
+// I have no clue how this works or what it does, but it doesn't work without it
+void isr_remapPIC(void) {
+	outb(0x20, 0x11); iowait();
+	outb(0xa0, 0x11); iowait();
+	outb(0x21, 0x20); iowait();
+	outb(0xa1, 0x28); iowait();
+	outb(0x21, 0x04); iowait();
+	outb(0xa1, 0x02); iowait();
+	outb(0x21, 0x01); iowait();
+	outb(0xa1, 0x01); iowait();
+	outb(0x21, 0x00); iowait();
+	outb(0xa1, 0x00); iowait();
+}
+
+int isr_init(void) {
+	idt_init();
+	isr_remapPIC();
+
+	for (int i = 0; i < 48; i++) {
+		// First 32 IRSs are exceptions (traps) and the next 16 are hardware interrupts
+		idt_setGate(i, isr_redirectTable[i], (i < 32) ? IDT_FLAG_TRAP : IDT_FLAG_INT);
+	}
+
+	// System call (should be callable from userspace)
+	idt_setGate(0x80, (void*)(uint32_t)isr128, IDT_FLAG_USER);
+
+	// Let interrupts interrupt
+	__asm__ volatile ("sti");
+	return 0;
+}
+
+void isr_registerIRQ(uint8_t i, isr_handlerPtr handler) {
+	irqHandlers[i] = handler;
+}
+
+void isr_sendEOI(uint8_t irq) {
+	if (irq >= 8) {
+		outb(0xa0, 0x20);
+	}
+	outb(0x20, 0x20);
+}
+
+int isr_handleInterrupt(struct isr_intFrame iframe) {
+	if (iframe.interrupt < 32) { 
+		// ISRs 0-31 - Exceptions
+		panic(exceptions[iframe.interrupt]);
+	} else if (iframe.interrupt >= 32 && iframe.interrupt < 48) {
+		// ISRs 32-47 - Hardware interrupts
+		uint8_t irq = iframe.interrupt - 32;
+		if (irqHandlers[irq]) {
+			irqHandlers[irq](&iframe);
+			isr_sendEOI(irq);
+		}
+	} else if (iframe.interrupt == 128) { 
+		// ISR 128 - System call
+		return syscallHandler(&iframe);
+	}
+
+	return 0;
+}
+