/
cpu.go
executable file
·86 lines (65 loc) · 1.47 KB
/
cpu.go
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package rp2ago3
import (
"time"
"github.com/nwidger/m65go2"
)
const NTSC_CLOCK_RATE time.Duration = 187 * time.Nanosecond // 21.477272MHz / 4 = 5.369318MHz
const PAL_CLOCK_RATE time.Duration = 187 * time.Nanosecond // 26.601712MHz / 5 = 5.3203424MHz
const NTSC_CPU_CLOCK_DIVISOR uint16 = 3
const PAL_CPU_CLOCK_DIVISOR uint16 = 4
type RP2A03 struct {
*m65go2.M6502
*APU
dma *DMA
Memory *MappedMemory
}
func NewRP2A03() *RP2A03 {
mem := NewMappedMemory(m65go2.NewBasicMemory(m65go2.DEFAULT_MEMORY_SIZE))
mirrors := make(map[uint16]uint16)
// Mirrored 2KB internal RAM
for i := uint16(0x0800); i <= 0x1fff; i++ {
mirrors[i] = i % 0x0800
}
// Mirrored PPU registers
for i := uint16(0x2008); i <= 0x3fff; i++ {
mirrors[i] = 0x2000 + (i & 0x0007)
}
mem.AddMirrors(mirrors)
cpu := m65go2.NewM6502(mem)
cpu.DisableDecimalMode()
apu := NewAPU()
// APU memory maps
mem.AddMappings(apu, CPU)
dma := NewDMA(mem)
// DMA memory maps
mem.AddMappings(dma, CPU)
return &RP2A03{
Memory: mem,
M6502: cpu,
APU: apu,
dma: dma,
}
}
func (cpu *RP2A03) Reset() {
cpu.M6502.Reset()
cpu.APU.Reset()
cpu.Memory.Reset()
}
func (cpu *RP2A03) Run() (err error) {
var cycles uint16
for {
if cycles, err = cpu.Execute(); err != nil {
break
}
if cpu.Cycles != nil && cycles != 0 {
cpu.Cycles <- cycles
<-cpu.Cycles
}
cycles = cpu.dma.PerformDMA()
if cpu.Cycles != nil && cycles != 0 {
cpu.Cycles <- cycles
<-cpu.Cycles
}
}
return
}