2 files changed, 29 insertions(+), 0 deletions(-)

M sm83/cpu.ha
M sm83/exec.ha

@@ 49,6 49,16 @@ export fn reset(cpu: *sm83) void = {
 	};
 };
 
+// Sets the CPU interrupt mask.
+export fn imask(cpu: *sm83, mask: u8) void = {
+	cpu.int_ie = mask;
+};
+
+// Triggers the provided mask of interrupts.
+export fn raise(cpu: *sm83, mask: u8) void = {
+	cpu.int_if |= mask;
+};
+
 fn cycles(cpu: *sm83, n: int) void = {
 	cpu.cycles -= n;
 };

@@ 3,6 3,9 @@ export fn exec(cpu: *sm83, cycles: uint) void = {
 	cpu.cycles += cycles: int;
 
 	for (cpu.cycles > 0) {
+		if (cpu.int_ime == 1 && cpu.int_if & cpu.int_ie != 0) {
+			interrupt(cpu);
+		};
 		if (cpu.int_ime == 2) {
 			// EI is delayed by one instruction
 			cpu.int_ime = 1;


@@ 15,3 18,19 @@ export fn exec(cpu: *sm83, cycles: uint) void = {
 		};
 	};
 };
+
+fn interrupt(cpu: *sm83) void = {
+	cpu.cycles -= 5 * 4;
+	cpu.int_ime = 0;
+
+	let i = 0u8;
+	for (i < 8; i += 1) {
+		if (cpu.int_if & (1 << i) != 0) {
+			break;
+		};
+	};
+
+	cpu.int_if &= ~(1 << i);
+	push(cpu, cpu.regs.PC);
+	cpu.regs.PC = i * 8 + 0x40u16;
+};