test_cpu_simple - Add test for HALT with IME=1

tests/test_cpu_simple.cpp

@@ -249,3 +249,44 @@ TEST_CASE("DAA")
 
   CHECK(cpu.state.A == 0x45);
 }
+
+TEST_CASE("HALT exits on interrupt")
+{
+  u8 test_ram[] = {
+    0x76,
+    0x00,
+    0x00,
+  };
+
+  RAM r(test_ram, 0x3, true);
+  Cpu cpu(&r);
+
+  cpu.state.IE = INT_MASK;
+  cpu.state.IF = 0;
+  cpu.state.IME = IME_ON;
+
+  CHECK(cpu.state.halted == false);
+
+  cpu.step();
+  CHECK(cpu.state.halted == true);
+  CHECK(cpu.state.PC == 0x01);
+
+  cpu.step();
+  CHECK(cpu.state.halted == true);
+  CHECK(cpu.state.PC == 0x01);
+
+  cpu.step();
+  CHECK(cpu.state.halted == true);
+  CHECK(cpu.state.PC == 0x01);
+
+  cpu.signalInterrupt(INT_LCDSTAT);
+
+  CHECK(cpu.state.IF == INT_LCDSTAT);
+
+  cpu.step();
+
+  CHECK(cpu.state.halted == false);
+  CHECK(cpu.state.IF == 0);
+  CHECK(cpu.state.IME == IME_OFF);
+  CHECK(cpu.state.PC == 0x48);
+}