1 files changed, 86 insertions, 0 deletions
diff --git a/src/peripherals/gpio.spec.ts b/src/peripherals/gpio.spec.ts
new file mode 100644
index 0000000..5a282e6
--- /dev/null
+++ b/src/peripherals/gpio.spec.ts
@@ -0,0 +1,86 @@
+import { CPU } from '../cpu/cpu';
+import { AVRIOPort, portBConfig, PinState } from './gpio';
+
+describe('GPIO', () => {
+  it('should invoke the listeners when the port is written to', () => {
+    const cpu = new CPU(new Uint16Array(1024));
+    const port = new AVRIOPort(cpu, portBConfig);
+    const listener = jest.fn();
+    port.addListener(listener);
+    cpu.writeData(0x24, 0x0f); // DDRB <- 0x0f
+    cpu.writeData(0x25, 0x55); // PORTB <- 0x55
+    expect(listener).toHaveBeenCalledWith(0x05, 0);
+    expect(cpu.data[0x23]).toEqual(0x5); // PINB should return port value
+  });
+
+  it('should toggle the pin when writing to the PIN register', () => {
+    const cpu = new CPU(new Uint16Array(1024));
+    const port = new AVRIOPort(cpu, portBConfig);
+    const listener = jest.fn();
+    port.addListener(listener);
+    cpu.writeData(0x24, 0x0f); // DDRB <- 0x0f
+    cpu.writeData(0x25, 0x55); // PORTB <- 0x55
+    cpu.writeData(0x23, 0x01); // PINB <- 0x0f
+    expect(listener).toHaveBeenCalledWith(0x04, 0x5);
+    expect(cpu.data[0x23]).toEqual(0x4); // PINB should return port value
+  });
+
+  describe('removeListener', () => {
+    it('should remove the given listener', () => {
+      const cpu = new CPU(new Uint16Array(1024));
+      const port = new AVRIOPort(cpu, portBConfig);
+      const listener = jest.fn();
+      port.addListener(listener);
+      cpu.writeData(0x24, 0x0f); // DDRB <- 0x0f
+      port.removeListener(listener);
+      cpu.writeData(0x25, 0x99); // PORTB <- 0x99
+      expect(listener).not.toHaveBeenCalled();
+    });
+  });
+
+  describe('pinState', () => {
+    it('should return PinState.High when the pin set to output and HIGH', () => {
+      const cpu = new CPU(new Uint16Array(1024));
+      const port = new AVRIOPort(cpu, portBConfig);
+      cpu.writeData(0x24, 0x1); // DDRB <- 0x1
+      cpu.writeData(0x25, 0x1); // PORTB <- 0x1
+      expect(port.pinState(0)).toEqual(PinState.High);
+    });
+
+    it('should return PinState.Low when the pin set to output and LOW', () => {
+      const cpu = new CPU(new Uint16Array(1024));
+      const port = new AVRIOPort(cpu, portBConfig);
+      cpu.writeData(0x24, 0x8); // DDRB <- 0x8
+      cpu.writeData(0x25, 0xf7); // PORTB <- 0xF7 (~8)
+      expect(port.pinState(3)).toEqual(PinState.Low);
+    });
+
+    it('should return PinState.Input by default (reset state)', () => {
+      const cpu = new CPU(new Uint16Array(1024));
+      const port = new AVRIOPort(cpu, portBConfig);
+      expect(port.pinState(1)).toEqual(PinState.Input);
+    });
+
+    it('should return PinState.InputPullUp when the pin is set to input with pullup', () => {
+      const cpu = new CPU(new Uint16Array(1024));
+      const port = new AVRIOPort(cpu, portBConfig);
+      cpu.writeData(0x24, 0); // DDRB <- 0
+      cpu.writeData(0x25, 0x2); // PORTB <- 0x2
+      expect(port.pinState(1)).toEqual(PinState.InputPullUp);
+    });
+
+    it('should reflect the current port state when called inside a listener', () => {
+      // Related issue: https://github.com/wokwi/avr8js/issues/9
+      const cpu = new CPU(new Uint16Array(1024));
+      const port = new AVRIOPort(cpu, portBConfig);
+      const listener = jest.fn(() => {
+        expect(port.pinState(0)).toBe(PinState.High);
+      });
+      port.addListener(listener);
+      expect(port.pinState(0)).toBe(PinState.Input);
+      cpu.writeData(0x24, 0x01); // DDRB <- 0x01
+      cpu.writeData(0x25, 0x01); // PORTB <- 0x01
+      expect(listener).toHaveBeenCalled();
+    });
+  });
+});