From da7bb3ebf78baa0b8772ca4c3e4f275e5147482c Mon Sep 17 00:00:00 2001
From: Rob Greene <robgreene@gmail.com>
Date: Fri, 13 Mar 2020 21:29:12 -0500
Subject: [PATCH] Adding pause capability.

---
 apple2.go                | 18 +++++++++++++++++-
 apple2sdl/main.go        | 10 ++++++++++
 apple2sdl/sdlKeyboard.go |  2 ++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/apple2.go b/apple2.go
index fc6705d..7545592 100644
--- a/apple2.go
+++ b/apple2.go
@@ -27,6 +27,7 @@ type Apple2 struct {
 	fastRequestsCounter int
 	profile             bool
 	showSpeed           bool
+	paused              bool
 }
 
 const (
@@ -48,7 +49,13 @@ func (a *Apple2) Run() {
 
 	for {
 		// Run a 6502 step
-		a.cpu.ExecuteInstruction()
+		if !a.paused {
+			a.cpu.ExecuteInstruction()
+		} else {
+			time.Sleep(200 * time.Millisecond)
+			referenceTime = time.Now()
+			speedReferenceTime = referenceTime
+		}
 
 		// Execute meta commands
 		commandsPending := true
@@ -92,6 +99,11 @@ func (a *Apple2) Run() {
 	}
 }
 
+// IsPaused returns true when emulator is paused
+func (a *Apple2) IsPaused() bool {
+	return a.paused
+}
+
 func (a *Apple2) setProfiling(value bool) {
 	a.profile = value
 }
@@ -122,6 +134,8 @@ const (
 	CommandKill
 	// CommandReset executes a 6502 reset
 	CommandReset
+	// CommandPauseUnpauseEmulator allows the Pause button to freeze the emulator for a coffee break
+	CommandPauseUnpauseEmulator
 )
 
 // SendCommand enqueues a command to the emulator thread
@@ -164,6 +178,8 @@ func (a *Apple2) executeCommand(command int) {
 		a.cpu.SetTrace(!a.cpu.GetTrace())
 	case CommandReset:
 		a.cpu.Reset()
+	case CommandPauseUnpauseEmulator:
+		a.paused = !a.paused
 	}
 }
 
diff --git a/apple2sdl/main.go b/apple2sdl/main.go
index c64d60b..f9f5c4f 100644
--- a/apple2sdl/main.go
+++ b/apple2sdl/main.go
@@ -47,6 +47,7 @@ func SDLRun(a *apple2.Apple2) {
 
 	go a.Run()
 
+	paused := false
 	running := true
 	for running {
 		for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
@@ -66,6 +67,15 @@ func SDLRun(a *apple2.Apple2) {
 			}
 		}
 
+		if paused != a.IsPaused() {
+			if a.IsPaused() {
+				window.SetTitle(a.Name + " - PAUSED!")
+			} else {
+				window.SetTitle(a.Name)
+			}
+			paused = a.IsPaused()
+		}
+
 		img := apple2.Snapshot(a)
 		if img != nil {
 			surface, err := sdl.CreateRGBSurfaceFrom(unsafe.Pointer(&img.Pix[0]),
diff --git a/apple2sdl/sdlKeyboard.go b/apple2sdl/sdlKeyboard.go
index 5565700..6aca3eb 100644
--- a/apple2sdl/sdlKeyboard.go
+++ b/apple2sdl/sdlKeyboard.go
@@ -123,6 +123,8 @@ func (k *sdlKeyboard) putKey(keyEvent *sdl.KeyboardEvent) {
 		} else {
 			fmt.Println("Saving snapshot")
 		}
+	case sdl.K_PAUSE:
+		k.a.SendCommand(apple2.CommandPauseUnpauseEmulator)
 	}
 
 	// Missing values 91 to 95. Usually control for [\]^_