1 files changed, 143 insertions, 0 deletions
diff --git a/src/drivers/interrupts.c b/src/drivers/interrupts.c
new file mode 100644
index 0000000..23cbf72
--- /dev/null
+++ b/src/drivers/interrupts.c
@@ -0,0 +1,143 @@
+// MIT License, Copyright (c) 2020 Marvin Borner
+
+#include <cpu.h>
+#include <def.h>
+#include <interrupts.h>
+#include <serial.h>
+
+/**
+ * IDT
+ */
+
+void idt_set_gate(u8 num, u32 base, u16 sel, u8 flags)
+{
+	// Specify the interrupt routine's base address
+	idt[num].base_low = (u16)(base & 0xFFFF);
+	idt[num].base_high = (u16)((base >> 16) & 0xFFFF);
+
+	// Set selector/segment of IDT entry
+	idt[num].sel = sel;
+	idt[num].always0 = 0;
+	idt[num].flags = (u8)(flags | 0x60);
+}
+
+// Install IDT
+void idt_install()
+{
+	// Set IDT pointer and limit
+	idt_ptr.limit = (sizeof(struct idt_entry) * 256) - 1;
+	idt_ptr.base = &idt;
+
+	// Clear IDT by setting memory cells to 0
+	//memset(&idt, 0, sizeof(struct idt_entry) * 256);
+
+	__asm__("lidt %0" : : "m"(idt_ptr));
+}
+
+/**
+ * IRQ
+ */
+
+void (*irq_routines[16])(struct regs *) = { 0 };
+
+// Install IRQ handler
+void irq_install_handler(int irq, void (*handler)(struct regs *r))
+{
+	irq_routines[irq] = handler;
+}
+
+// Remove IRQ handler
+void irq_uninstall_handler(int irq)
+{
+	irq_routines[irq] = 0;
+}
+
+// Remap the IRQ table
+void irq_remap()
+{
+	outb(0x20, 0x11);
+	outb(0xA0, 0x11);
+	outb(0x21, 0x20);
+	outb(0xA1, 0x28);
+	outb(0x21, 0x04);
+	outb(0xA1, 0x02);
+	outb(0x21, 0x01);
+	outb(0xA1, 0x01);
+	outb(0x21, 0x00);
+	outb(0xA1, 0x00);
+}
+
+// Handle IRQ ISRs
+__attribute__((interrupt)) void irq_handler(struct regs *r)
+{
+	void (*handler)(struct regs * r);
+
+	// Execute custom handler if exists
+	handler = irq_routines[r->int_no - 32];
+	if (handler)
+		handler(r);
+
+	// Send EOI to second (slave) PIC
+	if (r->int_no >= 40)
+		outb(0xA0, 0x20);
+
+	// Send EOI to master PIC
+	outb(0x20, 0x20);
+}
+
+// Map ISRs to the correct entries in the IDT
+void irq_install()
+{
+	irq_remap();
+	for (int i = 32; i < 48; i++)
+		idt_set_gate(i, (u32)irq_handler, 0x08, 0x8E);
+}
+
+/**
+ * ISR
+ */
+
+void (*isr_routines[256])(struct regs *) = { 0 };
+
+void isr_install_handler(int isr, void (*handler)(struct regs *r))
+{
+	isr_routines[isr] = handler;
+}
+
+void isr_uninstall_handler(int isr)
+{
+	isr_routines[isr] = 0;
+}
+
+__attribute__((interrupt)) void isr_handler(struct regs *r)
+{
+	void (*handler)(struct regs * r);
+
+	// Execute fault handler if exists
+	handler = isr_routines[r->int_no];
+	if (handler) {
+		handler(r);
+	} else {
+		serial_print("Got ISR!\n");
+		__asm__("cli");
+		while (1) {
+		};
+	}
+}
+
+void isr_install()
+{
+	for (int i = 0; i < 32; i++)
+		idt_set_gate(i, (u32)isr_handler, 0x08, 0x8E);
+}
+
+/**
+ * Combined
+ */
+void interrupts_install()
+{
+	idt_install();
+	isr_install();
+	irq_install();
+	__asm__("sti");
+}