1 files changed, 92 insertions, 0 deletions
diff --git a/src/interrupt.c b/src/interrupt.c
new file mode 100644
index 0000000..e588353
--- /dev/null
+++ b/src/interrupt.c
@@ -0,0 +1,92 @@
+
+#include "interrupt.h"
+#include "string.h"
+#include "vga.h"
+#include "bees.h"
+#include "printf.h"
+#include "keyboard.h"
+
+struct port pic_master_command = {0x20, port8bit_slow};
+struct port pic_master_data = {0x21, port8bit_slow};
+struct port pic_slave_command = {0xA0, port8bit_slow};
+struct port pic_slave_data = {0xA1, port8bit_slow}; 
+
+struct port ps2_port = {0x60, port8bit};
+
+struct gate_desc idt[256] = {0};
+
+#define PIC_EOI 0x20
+
+void irq_end(uint8_t int_number) {
+	if (int_number >= 0x28)
+		port_write(pic_slave_command, PIC_EOI);
+	port_write(pic_master_command, PIC_EOI);
+}
+
+uint32_t handle_int(uint8_t int_number, uint32_t idk, uint32_t esp) {
+	switch (int_number) {
+		case 0x0D:
+			// bye
+			bees("general protection fault");
+			break;
+		case 0x21:
+			process_scancode(port_read(ps2_port));
+			irq_end(int_number);
+			break;
+	}
+
+	return esp;
+}
+
+void set_int_desc_entry(uint8_t int_number, uint16_t gdt_code_seg,
+						void (*handler)(), uint8_t privilege_level,
+						uint8_t desc_type) {
+	const uint8_t IDT_DESC_PRESENT = 0x80;
+	
+	idt[int_number].handler_low = ((uint32_t) handler) & 0xFFFF;
+	idt[int_number].handler_high = ((uint32_t) handler >> 16) & 0xFFFF;
+	idt[int_number].gdt_code_seg = gdt_code_seg;
+	idt[int_number].access = IDT_DESC_PRESENT | desc_type | ((privilege_level&3) << 5);
+	idt[int_number].reserved = 0;
+}
+
+void interrupt_init() {
+	uint16_t code_seg = 0x08;
+	const uint8_t IDT_INTERRUPT_GATE = 0xE;
+
+	for (uint16_t i = 0; i < 256; i++)
+		set_int_desc_entry(i, code_seg, &int_ignore, 0, IDT_INTERRUPT_GATE);
+	
+	// Put the interrupt handlers in the IDT
+	set_int_desc_entry(0x20, code_seg, &handle_irq0x00, 0, IDT_INTERRUPT_GATE);
+	set_int_desc_entry(0x21, code_seg, &handle_irq0x01, 0, IDT_INTERRUPT_GATE);
+	set_int_desc_entry(0x0D, code_seg, &handle_irq0x0D, 0, IDT_INTERRUPT_GATE);
+
+	port_write(pic_master_command, 0x11);
+	port_write(pic_slave_command, 0x11);
+	
+	// (I actually don't understand how this works)
+	// Remap the PIC
+	port_write(pic_master_data, 0x20);  // Interrupt vector offsets 
+	port_write(pic_slave_data, 0x28); 
+	
+	port_write(pic_master_data, 0x04);  // There is a slave PIC at IRQ2
+	port_write(pic_slave_data, 0x02);   // Slave PIC cascade identity
+
+	port_write(pic_master_data, 0x01);
+	port_write(pic_slave_data, 0x01);
+
+	port_write(pic_master_data, 0xFD);  
+	port_write(pic_slave_data, 0xFF);   
+
+	// Load the IDT
+	struct idt_pointer i;
+	i.size = 256 * sizeof(struct gate_desc) - 1;
+	i.base = (uint32_t) idt;
+	
+	asm volatile("lidt %0" : : "m" (i));
+}
+
+void start_interrupts() {
+	asm("sti");
+}