go/chip8-emulator
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This commit is contained in:
Jairinho 2022-02-23 17:47:52 -03:00
parent 9930d1666c
commit 871ba092ce
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GPG Key ID: 954589B18A21D5B6
2 changed files with 77 additions and 11 deletions
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67
chip8/chip8.go
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@ -53,16 +53,61 @@ func (emulator *Emulator) Step() {
instruction := binary.BigEndian.Uint16(emulator.Memory[emulator.PC:])
switch instruction & 0xF000 {
case 0x1000: // 1nnn - JP addr
emulator.Jump(instruction & 0x0FFF)
case 0x2000: // 2nnn - CALL addr
emulator.Call(instruction & 0x0FFF)
case 0x3000: // 3xkk - SE Vx, byte
emulator.SkipEqual(uint8(instruction&0x0F00>>8), uint8(instruction&0x00FF))
case 0x4000: // 4xkk - SNE Vx, byte
emulator.SkipNotEqual(uint8(instruction&0x0F00>>8), uint8(instruction&0x00FF))
case 0x5000: // 5xy0 - SE Vx, Vy
emulator.SkipRegistersEqual(uint8(instruction&0x0F00>>8), uint8(instruction&0x00F0>>4))
nnn := instruction & 0x0FFF
// n := uint8(instruction & 0x000F)
kk := uint8(instruction & 0x00FF)
x := uint8(instruction & 0x0F00 >> 8)
y := uint8(instruction & 0x00F0 >> 4)
switch instruction & 0xF000 >> 12 {
case 0x1: // 1nnn - JP addr
emulator.Jump(nnn)
case 0x2: // 2nnn - CALL addr
emulator.Call(nnn)
case 0x3: // 3xkk - SE Vx, byte
emulator.SkipEqual(x, kk)
case 0x4: // 4xkk - SNE Vx, byte
emulator.SkipNotEqual(x, kk)
case 0x5: // 5xy0 - SE Vx, Vy
emulator.SkipRegistersEqual(x, y)
case 0x6: // 6xkk - LD Vx, byte
emulator.LoadByte(x, kk)
case 0x7: // 7xkk - ADD Vx, byte
emulator.Add(x, kk)
case 0x8:
switch instruction & 0x000F {
case 0x0: // 8xy0 - LD Vx, Vy
emulator.LoadRegister(x, y)
case 0x1: // 8xy1 - OR Vx, Vy
case 0x2: // 8xy2 - AND Vx, Vy
case 0x3: // 8xy3 - XOR Vx, Vy
case 0x4: // 8xy4 - ADD Vx, Vy
case 0x5: // 8xy5 - SUB Vx, Vy
case 0x6: // 8xy6 - SHR Vx {, Vy}
case 0x7: // 8xy7 - SUBN Vx, Vy
case 0xE: // 8xyE - SHL Vx {, Vy}
}
case 0x9: // 9xy0 - SNE Vx, Vy
case 0xA: // Annn - LD I, addr
case 0xB: // Bnnn - JP V0, addr
case 0xC: // Cxkk - RND Vx, byte
case 0xD: // Dxyn - DRW Vx, Vy, nibble
case 0xE:
switch instruction & 0x00FF {
case 0x9E: // SKP Vx
case 0xA1: // SKNP Vx
}
case 0xF:
switch instruction & 0x00FF {
case 0x07: // LD Vx, DT
case 0x0A: // LD Vx, K
case 0x15: // LD DT, Vx
case 0x18: // LD ST, Vx
case 0x1E: // ADD I, Vx
case 0x29: // LD F, Vx
case 0x33: // LD B, Vx
case 0x55: // LD [I], Vx
case 0x65: // LD Vx, [I]
}
}
}

21
chip8/instructions.go
View File

@ -60,3 +60,24 @@ func (emulator *Emulator) SkipRegistersEqual(x uint8, y uint8) {
emulator.PC += InstructionSize
}
}
// Set Vx = kk.
//
// The interpreter puts the value kk into register Vx.
func (emulator *Emulator) LoadByte(x uint8, kk uint8) {
emulator.V[x] = kk
}
// Set Vx = Vx + kk.
//
// Adds the value kk to the value of register Vx, then stores the result in Vx.
func (emulator *Emulator) Add(x uint8, kk uint8) {
emulator.V[x] += kk
}
// Set Vx = Vy.
//
// Stores the value of register Vy in register Vx.
func (emulator *Emulator) LoadRegister(x uint8, y uint8) {
emulator.V[x] = emulator.V[y]
}