izapple2/apple2.go

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package izapple2
import (
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"fmt"
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"sync/atomic"
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"time"
"github.com/ivanizag/iz6502"
)
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// Apple2 represents all the components and state of the emulated machine
type Apple2 struct {
Name string
cpu *iz6502.State
mmu *memoryManager
io *ioC0Page
cg *CharacterGenerator
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cards [8]Card
softVideoSwitch *SoftVideoSwitch
isApple2e bool
commandChannel chan int
cycleDurationNs float64 // Current speed. Inverse of the cpu clock in Ghz
fastMode bool
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fastRequestsCounter int32
cycleBreakpoint uint64
breakPoint bool
profile bool
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showSpeed bool
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paused bool
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tracers []executionTracer
forceCaps bool
}
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type executionTracer interface {
inspect()
}
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const (
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// CPUClockMhz is the actual Apple II clock speed
CPUClockMhz = 14.318 / 14
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cpuClockEuroMhz = 14.238 / 14
)
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const (
maxWaitDuration = 100 * time.Millisecond
cpuSpinLoops = 100
)
// Run starts the Apple2 emulation
func (a *Apple2) Run() {
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a.Start(false)
}
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// Start the Apple2 emulation, can start paused
func (a *Apple2) Start(paused bool) {
// Start the processor
a.cpu.Reset()
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referenceTime := time.Now()
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speedReferenceTime := referenceTime
speedReferenceCycles := uint64(0)
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a.paused = paused
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
//pc, _ := a.cpu.GetPCAndSP()
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//a.cpu.SetTrace((pc >= 0xc500 && pc < 0xc600) || (pc >= 0xc700 && 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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if a.cycleBreakpoint != 0 && a.cpu.GetCycles() >= a.cycleBreakpoint {
a.breakPoint = true
a.cycleBreakpoint = 0
a.paused = true
}
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} else {
time.Sleep(200 * time.Millisecond)
}
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// Execute meta commands
commandsPending := true
for commandsPending {
select {
case command := <-a.commandChannel:
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switch command {
case CommandKill:
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return
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case CommandPause:
if !a.paused {
a.paused = true
}
case CommandStart:
if a.paused {
a.paused = false
referenceTime = time.Now()
speedReferenceTime = referenceTime
}
case CommandPauseUnpause:
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a.paused = !a.paused
referenceTime = time.Now()
speedReferenceTime = referenceTime
default:
// Execute the other commands
a.executeCommand(command)
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}
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default:
commandsPending = false
}
}
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)
simulatedDuration := time.Duration(float64(a.cpu.GetCycles()) * a.cycleDurationNs)
waitDuration := simulatedDuration - clockDuration
if waitDuration > maxWaitDuration || -waitDuration > maxWaitDuration {
// We have to wait too long or are too much behind. Let's fast forward
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referenceTime = referenceTime.Add(-waitDuration)
waitDuration = 0
}
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if waitDuration > 0 {
time.Sleep(waitDuration)
}
}
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if a.showSpeed && a.cpu.GetCycles()-speedReferenceCycles > 1000000 {
// Calculate speed in MHz every million cycles
newTime := time.Now()
newCycles := a.cpu.GetCycles()
elapsedCycles := float64(newCycles - speedReferenceCycles)
freq := 1000.0 * elapsedCycles / float64(newTime.Sub(speedReferenceTime).Nanoseconds())
fmt.Printf("Freq: %f Mhz\n", freq)
speedReferenceTime = newTime
speedReferenceCycles = newCycles
}
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}
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}
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func (a *Apple2) reset() {
a.cpu.Reset()
a.mmu.reset()
for _, c := range a.cards {
if c != nil {
c.reset()
}
}
}
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// IsPaused returns true when emulator is paused
func (a *Apple2) IsPaused() bool {
return a.paused
}
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func (a *Apple2) GetCycles() uint64 {
return a.cpu.GetCycles()
}
// SetCycleBreakpoint sets a cycle number to pause the emulator. 0 to disable
func (a *Apple2) SetCycleBreakpoint(cycle uint64) {
a.cycleBreakpoint = cycle
a.breakPoint = false
}
func (a *Apple2) BreakPoint() bool {
return a.breakPoint
}
func (a *Apple2) setProfiling(value bool) {
a.profile = value
}
// IsProfiling returns true when profiling
func (a *Apple2) IsProfiling() bool {
return a.profile
}
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// SetForceCaps allows the caps state to be toggled at runtime
func (a *Apple2) SetForceCaps(value bool) {
a.forceCaps = value
}
// IsForceCaps returns true when all letters are forced to upper case
func (a *Apple2) IsForceCaps() bool {
return a.forceCaps
}
const (
// CommandToggleSpeed toggles cpu speed between full speed and actual Apple II speed
CommandToggleSpeed = iota + 1
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// CommandShowSpeed toggles printinf the current freq in Mhz
CommandShowSpeed
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// CommandDumpDebugInfo dumps useful info
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CommandDumpDebugInfo
// CommandNextCharGenPage cycles the CharGen page if several
CommandNextCharGenPage
// CommandToggleCPUTrace toggle tracing of CPU execution
CommandToggleCPUTrace
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// CommandKill stops the cpu execution loop
CommandKill
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// CommandReset executes a 6502 reset
CommandReset
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// CommandPauseUnpause allows the Pause button to freeze the emulator for a coffee break
CommandPauseUnpause
// CommandPause pauses the emulator
CommandPause
// CommandStart restarts the emulator
CommandStart
)
// SendCommand enqueues a command to the emulator thread
func (a *Apple2) SendCommand(command int) {
a.commandChannel <- command
}
func (a *Apple2) executeCommand(command int) {
switch command {
case CommandToggleSpeed:
if a.cycleDurationNs == 0 {
//fmt.Println("Slow")
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a.cycleDurationNs = 1000.0 / CPUClockMhz
} else {
//fmt.Println("Fast")
a.cycleDurationNs = 0
}
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case CommandShowSpeed:
a.showSpeed = !a.showSpeed
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case CommandDumpDebugInfo:
a.dumpDebugInfo()
case CommandNextCharGenPage:
a.cg.nextPage()
fmt.Printf("Chargen page %v\n", a.cg.page)
case CommandToggleCPUTrace:
a.cpu.SetTrace(!a.cpu.GetTrace())
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case CommandReset:
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a.reset()
}
}
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func (a *Apple2) RequestFastMode() {
// Note: if the fastMode is shorter than maxWaitDuration, there won't be any gain.
if a.fastMode {
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atomic.AddInt32(&a.fastRequestsCounter, 1)
}
}
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func (a *Apple2) ReleaseFastMode() {
if a.fastMode {
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atomic.AddInt32(&a.fastRequestsCounter, -1)
}
}
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func (a *Apple2) executionTrace() {
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if a.tracers != nil {
for _, v := range a.tracers {
v.inspect()
}
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}
}
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func (a *Apple2) dumpDebugInfo() {
// See "Apple II Monitors Peeled"
pageZeroSymbols := map[int]string{
0x36: "CSWL",
0x37: "CSWH",
0x38: "KSWL",
0x39: "KSWH",
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0xe2: "ACJVAFLDL", // Apple Pascal
0xe3: "ACJVAFLDH", // Apple Pascal
0xec: "JVBFOLDL", // Apple Pascal
0xed: "JVBFOLDH", // Apple Pascal
0xee: "JVAFOLDL", // Apple Pascal
0xef: "JVAFOLDH", // Apple Pascal
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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]
fmt.Printf(" %v(0x%x): 0x%02x\n", pageZeroSymbols[k], k, d)
}
}