WIP: CPU

gb/cpu.go

@@ -0,0 +1,81 @@
+package gb
+
+import (
+	"fmt"
+)
+
+const CPUFrequency = 4194304
+
+type Registers struct {
+	A  byte
+	F  byte
+	B  byte
+	C  byte
+	D  byte
+	E  byte
+	H  byte
+	L  byte
+	PC uint16
+	SP uint16
+}
+
+type CPU struct {
+	Bus                    *Bus
+	Regs                   Registers
+	FetchedData            uint16
+	MemoryDestination      uint16
+	DestinationIsMemory    bool
+	CurrentOpcode          byte
+	Halted                 bool
+	Stepping               bool
+	InterruptMasterEnabled bool
+	CurrentInstruction     string
+}
+
+func NewCPU(bus *Bus) *CPU {
+	cpu := CPU{}
+	cpu.Bus = bus
+	cpu.Regs = Registers{PC: 0x100}
+	cpu.Stepping = true
+
+	return &cpu
+}
+
+func (cpu *CPU) Step() error {
+	if !cpu.Halted {
+		err := cpu.fetchInstruction()
+		if err != nil {
+			return fmt.Errorf("Error fetching instruction: %s", err)
+		}
+		cpu.fetchData()
+		cpu.execute()
+	}
+
+	return nil
+}
+
+func (cpu *CPU) fetchInstruction() error {
+	opcode, err := cpu.Bus.Read(cpu.Regs.PC)
+	if err != nil {
+		return fmt.Errorf("Error fetching instruction at address %X", cpu.Regs.PC)
+	}
+	cpu.CurrentOpcode = opcode
+	cpu.CurrentInstruction, err = InstructionByOpcode(cpu.CurrentOpcode)
+	if err != nil {
+		return fmt.Errorf("Error translating opcode %02X: %s at PC: %04X", cpu.CurrentOpcode, err, cpu.Regs.PC)
+	}
+
+	fmt.Printf("Executing instruction: %02X	PC: %04X\n", cpu.CurrentOpcode, cpu.Regs.PC)
+
+	cpu.Regs.PC++
+
+	return nil
+}
+
+func (cpu *CPU) fetchData() {
+
+}
+
+func (cpu *CPU) execute() {
+	fmt.Println("Not executing yet...")
+}