mirror of
https://github.com/ivanizag/izapple2.git
synced 2024-08-31 14:30:09 +00:00
154 lines
3.5 KiB
Go
154 lines
3.5 KiB
Go
package izapple2
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import (
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"fmt"
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"time"
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)
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const (
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// CPUClockMhz is the actual Apple II clock speed
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CPUClockMhz = 14.318 / 14
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cpuClockEuroMhz = 14.238 / 14
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)
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const (
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maxWaitDuration = 100 * time.Millisecond
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cpuSpinLoops = 100
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)
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// Run starts the Apple2 emulation
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func (a *Apple2) Run() {
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a.Start(false)
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}
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// Start the Apple2 emulation, can start paused
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func (a *Apple2) Start(paused bool) {
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// Start the processor
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a.cpu.Reset()
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referenceTime := time.Now()
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speedReferenceTime := referenceTime
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speedReferenceCycles := uint64(0)
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a.paused = paused
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for {
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// Run 6502 steps
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if !a.paused {
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for i := 0; i < cpuSpinLoops; i++ {
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// Conditional tracing
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//pc, _ := a.cpu.GetPCAndSP()
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//a.cpu.SetTrace(pc >= 0xc75e && pc < 0xc800)
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// Execution
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a.cpu.ExecuteInstruction()
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// Special tracing
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a.executionTrace()
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}
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if a.cycleBreakpoint != 0 && a.cpu.GetCycles() >= a.cycleBreakpoint {
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a.breakPoint = true
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a.cycleBreakpoint = 0
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a.paused = true
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}
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} else {
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time.Sleep(200 * time.Millisecond)
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}
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// Execute meta commands
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commandsPending := true
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for commandsPending {
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select {
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case command := <-a.commandChannel:
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switch command.getId() {
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case CommandKill:
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return
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case CommandPause:
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if !a.paused {
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a.paused = true
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}
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case CommandStart:
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if a.paused {
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a.paused = false
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referenceTime = time.Now()
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speedReferenceTime = referenceTime
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}
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case CommandPauseUnpause:
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a.paused = !a.paused
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referenceTime = time.Now()
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speedReferenceTime = referenceTime
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default:
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// Execute the other commands
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a.executeCommand(command)
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}
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default:
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commandsPending = false
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}
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}
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if a.cycleDurationNs != 0 && a.fastRequestsCounter <= 0 {
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// Wait until next 6502 step has to run
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clockDuration := time.Since(referenceTime)
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simulatedDuration := time.Duration(float64(a.cpu.GetCycles()) * a.cycleDurationNs)
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waitDuration := simulatedDuration - clockDuration
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if waitDuration > maxWaitDuration || -waitDuration > maxWaitDuration {
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// We have to wait too long or are too much behind. Let's fast forward
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referenceTime = referenceTime.Add(-waitDuration)
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waitDuration = 0
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}
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if waitDuration > 0 {
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time.Sleep(waitDuration)
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}
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}
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if a.showSpeed && a.cpu.GetCycles()-speedReferenceCycles > 1000000 {
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// Calculate speed in MHz every million cycles
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newTime := time.Now()
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newCycles := a.cpu.GetCycles()
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elapsedCycles := float64(newCycles - speedReferenceCycles)
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freq := 1000.0 * elapsedCycles / float64(newTime.Sub(speedReferenceTime).Nanoseconds())
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fmt.Printf("Freq: %f Mhz\n", freq)
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speedReferenceTime = newTime
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speedReferenceCycles = newCycles
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}
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}
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}
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func (a *Apple2) reset() {
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a.cpu.Reset()
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a.mmu.reset()
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for _, c := range a.cards {
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if c != nil {
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c.reset()
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}
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}
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}
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func (a *Apple2) executionTrace() {
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for _, v := range a.tracers {
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v.inspect()
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}
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}
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func (a *Apple2) dumpDebugInfo() {
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// See "Apple II Monitors Peeled"
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pageZeroSymbols := map[int]string{
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0x36: "CSWL",
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0x37: "CSWH",
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0x38: "KSWL",
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0x39: "KSWH",
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0xe2: "ACJVAFLDL", // Apple Pascal
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0xe3: "ACJVAFLDH", // Apple Pascal
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0xec: "JVBFOLDL", // Apple Pascal
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0xed: "JVBFOLDH", // Apple Pascal
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0xee: "JVAFOLDL", // Apple Pascal
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0xef: "JVAFOLDH", // Apple Pascal
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}
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fmt.Printf("Page zero values:\n")
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for _, k := range []int{0x36, 0x37, 0x38, 0x39, 0xe2, 0xe3, 0xec, 0xed, 0xee, 0xef} {
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d := a.mmu.physicalMainRAM.data[k]
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fmt.Printf(" %v(0x%x): 0x%02x\n", pageZeroSymbols[k], k, d)
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}
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}
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