test(usart): extract constants

This makes the test code easier to read

1 files changed, 68 insertions, 49 deletions

diff --git a/src/peripherals/usart.spec.ts b/src/peripherals/usart.spec.ts
index d9843dc..cda141d 100644
--- a/src/peripherals/usart.spec.ts
+++ b/src/peripherals/usart.spec.ts
@@ -4,57 +4,76 @@ import { AVRUSART, usart0Config } from './usart';
 const FREQ_16MHZ = 16e6;
 const FREQ_11_0529MHZ = 11059200;
 
+// CPU registers
+const SREG = 95;
+
+// USART0 Registers
+const UCSR0A = 0xc0;
+const UCSR0B = 0xc1;
+const UCSR0C = 0xc3;
+const UBRR0L = 0xc4;
+const UBRR0H = 0xc5;
+const UDR0 = 0xc6;
+
+// Register bit names
+const U2X0 = 2;
+const TXEN = 8;
+const UDRIE = 0x20;
+const TXCIE = 0x40;
+const TXC = 0x40;
+const UDRE = 0x20;
+
 describe('USART', () => {
   it('should correctly calculate the baudRate from UBRR', () => {
     const cpu = new CPU(new Uint16Array(1024));
     const usart = new AVRUSART(cpu, usart0Config, FREQ_11_0529MHZ);
-    cpu.writeData(0xc5, 0); // UBRR0H <- 0
-    cpu.writeData(0xc4, 5); // UBRR0L <- 5
+    cpu.writeData(UBRR0H, 0);
+    cpu.writeData(UBRR0L, 5);
     expect(usart.baudRate).toEqual(115200);
   });
 
   it('should correctly calculate the baudRate from UBRR in double-speed mode', () => {
     const cpu = new CPU(new Uint16Array(1024));
     const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
-    cpu.writeData(0xc5, 3); // UBRR0H <- 3
-    cpu.writeData(0xc4, 64); // UBRR0L <- 64
-    cpu.writeData(0xc0, 2); // UCSR0A: U2X0
+    cpu.writeData(UBRR0H, 3);
+    cpu.writeData(UBRR0L, 64);
+    cpu.writeData(UCSR0A, U2X0);
     expect(usart.baudRate).toEqual(2400);
   });
 
   it('should return 5-bits per byte when UCSZ = 0', () => {
     const cpu = new CPU(new Uint16Array(1024));
     const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
-    cpu.writeData(0xc0, 0);
+    cpu.writeData(UCSR0C, 0);
     expect(usart.bitsPerChar).toEqual(5);
   });
 
   it('should return 6-bits per byte when UCSZ = 1', () => {
     const cpu = new CPU(new Uint16Array(1024));
     const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
-    cpu.writeData(0xc0, 0x2);
+    cpu.writeData(UCSR0A, 0x2);
     expect(usart.bitsPerChar).toEqual(6);
   });
 
   it('should return 7-bits per byte when UCSZ = 2', () => {
     const cpu = new CPU(new Uint16Array(1024));
     const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
-    cpu.writeData(0xc0, 0x4);
+    cpu.writeData(UCSR0A, 0x4);
     expect(usart.bitsPerChar).toEqual(7);
   });
 
   it('should return 8-bits per byte when UCSZ = 3', () => {
     const cpu = new CPU(new Uint16Array(1024));
     const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
-    cpu.writeData(0xc0, 0x6);
+    cpu.writeData(UCSR0A, 0x6);
     expect(usart.bitsPerChar).toEqual(8);
   });
 
   it('should return 9-bits per byte when UCSZ = 7', () => {
     const cpu = new CPU(new Uint16Array(1024));
     const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
-    cpu.writeData(0xc0, 0x6);
-    cpu.writeData(0xc1, 0x4);
+    cpu.writeData(UCSR0A, 0x6);
+    cpu.writeData(UCSR0B, 0x4);
     expect(usart.bitsPerChar).toEqual(9);
   });
 
@@ -62,55 +81,55 @@ describe('USART', () => {
     const cpu = new CPU(new Uint16Array(1024));
     const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
     usart.onByteTransmit = jest.fn();
-    cpu.writeData(0xc1, 0x8); // UCSR0B <- TXEN
-    cpu.writeData(0xc6, 0x61); // UDR0
+    cpu.writeData(UCSR0B, TXEN);
+    cpu.writeData(UDR0, 0x61);
     expect(usart.onByteTransmit).toHaveBeenCalledWith(0x61);
   });
 
   it('should set UDRE and TXC flags after UDR0', () => {
     const cpu = new CPU(new Uint16Array(1024));
     new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
-    cpu.writeData(0xc1, 0x8); // UCSR0B <- TXEN
-    cpu.writeData(0xc0, 0); // UCSR0A <- 0
-    cpu.writeData(0xc6, 0x61); // UDR0
-    expect(cpu.data[0xc0]).toEqual(0x40 | 0x20); // UCSR0A: TXC | UDRE
+    cpu.writeData(UCSR0B, TXEN);
+    cpu.writeData(UCSR0A, 0);
+    cpu.writeData(UDR0, 0x61);
+    expect(cpu.data[UCSR0A]).toEqual(TXC | UDRE);
   });
 
   describe('tick()', () => {
     it('should trigger data register empty interrupt if UDRE is set', () => {
       const cpu = new CPU(new Uint16Array(1024));
       const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
-      cpu.writeData(0xc1, 0x28); // UCSR0B <- UDRIE | TXEN
-      cpu.writeData(0xc6, 0x61); // UDR0
-      cpu.data[95] = 0x80; // SREG: I-------
+      cpu.writeData(UCSR0B, UDRIE | TXEN);
+      cpu.writeData(0xc6, 0x61);
+      cpu.data[SREG] = 0x80; // SREG: I-------
       usart.tick();
       expect(cpu.pc).toEqual(0x26);
       expect(cpu.cycles).toEqual(2);
-      expect(cpu.data[0xc0] & 0x20).toEqual(0); // UCSR0A should clear UDRE
+      expect(cpu.data[UCSR0A] & UDRE).toEqual(0);
     });
 
     it('should trigger data tx complete interrupt if TXCIE is set', () => {
       const cpu = new CPU(new Uint16Array(1024));
       const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
-      cpu.writeData(0xc1, 0x48); // UCSR0B <- TXCIE | TXEN
-      cpu.writeData(0xc6, 0x61); // UDR0
-      cpu.data[95] = 0x80; // SREG: I-------
+      cpu.writeData(UCSR0B, TXCIE | TXEN);
+      cpu.writeData(UDR0, 0x61);
+      cpu.data[SREG] = 0x80; // SREG: I-------
       usart.tick();
       expect(cpu.pc).toEqual(0x28);
       expect(cpu.cycles).toEqual(2);
-      expect(cpu.data[0xc0] & 0x40).toEqual(0); // UCSR0A should clear TXC
+      expect(cpu.data[UCSR0A] & TXC).toEqual(0);
     });
 
     it('should not trigger any interrupt if interrupts are disabled', () => {
       const cpu = new CPU(new Uint16Array(1024));
       const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
-      cpu.writeData(0xc1, 0x28); // UCSR0B <- UDRIE | TXEN
-      cpu.writeData(0xc6, 0x61); // UDR0
-      cpu.data[95] = 0; // SREG: 0 (disable interrupts)
+      cpu.writeData(UCSR0B, UDRIE | TXEN);
+      cpu.writeData(UDR0, 0x61);
+      cpu.data[SREG] = 0; // SREG: 0 (disable interrupts)
       usart.tick();
       expect(cpu.pc).toEqual(0);
       expect(cpu.cycles).toEqual(0);
-      expect(cpu.data[0xc0]).toEqual(0x40 | 0x20); // UCSR0A: TXC | UDRE
+      expect(cpu.data[UCSR0A]).toEqual(TXC | UDRE);
     });
   });
 
@@ -119,13 +138,13 @@ describe('USART', () => {
       const cpu = new CPU(new Uint16Array(1024));
       const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
       usart.onLineTransmit = jest.fn();
-      cpu.writeData(0xc1, 0x8); // UCSR0B <- TXEN
-      cpu.writeData(0xc6, 0x48); // 'H'
-      cpu.writeData(0xc6, 0x65); // 'e'
-      cpu.writeData(0xc6, 0x6c); // 'l'
-      cpu.writeData(0xc6, 0x6c); // 'l'
-      cpu.writeData(0xc6, 0x6f); // 'o'
-      cpu.writeData(0xc6, 0xa); // '\n'
+      cpu.writeData(UCSR0B, TXEN);
+      cpu.writeData(UDR0, 0x48); // 'H'
+      cpu.writeData(UDR0, 0x65); // 'e'
+      cpu.writeData(UDR0, 0x6c); // 'l'
+      cpu.writeData(UDR0, 0x6c); // 'l'
+      cpu.writeData(UDR0, 0x6f); // 'o'
+      cpu.writeData(UDR0, 0xa); // '\n'
       expect(usart.onLineTransmit).toHaveBeenCalledWith('Hello');
     });
 
@@ -133,9 +152,9 @@ describe('USART', () => {
       const cpu = new CPU(new Uint16Array(1024));
       const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
       usart.onLineTransmit = jest.fn();
-      cpu.writeData(0xc1, 0x8); // UCSR0B <- TXEN
-      cpu.writeData(0xc6, 0x48); // 'H'
-      cpu.writeData(0xc6, 0x69); // 'i'
+      cpu.writeData(UCSR0B, TXEN);
+      cpu.writeData(UDR0, 0x48); // 'H'
+      cpu.writeData(UDR0, 0x69); // 'i'
       expect(usart.onLineTransmit).not.toHaveBeenCalled();
     });
 
@@ -143,16 +162,16 @@ describe('USART', () => {
       const cpu = new CPU(new Uint16Array(1024));
       const usart = new AVRUSART(cpu, usart0Config, FREQ_16MHZ);
       usart.onLineTransmit = jest.fn();
-      cpu.writeData(0xc1, 0x8); // UCSR0B <- TXEN
-      cpu.writeData(0xc6, 0x48); // 'H'
-      cpu.writeData(0xc6, 0x69); // 'i'
-      cpu.writeData(0xc6, 0xa); // '\n'
-      cpu.writeData(0xc6, 0x74); // 't'
-      cpu.writeData(0xc6, 0x68); // 'h'
-      cpu.writeData(0xc6, 0x65); // 'e'
-      cpu.writeData(0xc6, 0x72); // 'r'
-      cpu.writeData(0xc6, 0x65); // 'e'
-      cpu.writeData(0xc6, 0xa); // '\n'
+      cpu.writeData(UCSR0B, TXEN);
+      cpu.writeData(UDR0, 0x48); // 'H'
+      cpu.writeData(UDR0, 0x69); // 'i'
+      cpu.writeData(UDR0, 0xa); // '\n'
+      cpu.writeData(UDR0, 0x74); // 't'
+      cpu.writeData(UDR0, 0x68); // 'h'
+      cpu.writeData(UDR0, 0x65); // 'e'
+      cpu.writeData(UDR0, 0x72); // 'r'
+      cpu.writeData(UDR0, 0x65); // 'e'
+      cpu.writeData(UDR0, 0xa); // '\n'
       expect(usart.onLineTransmit).toHaveBeenCalledWith('there');
     });
   });