Support monochrome graphics

apple2/ioC0Page.go

@@ -85,6 +85,10 @@ func (p *ioC0Page) internalPeek(address uint8) uint8 {
 	return 0
 }
 
+func (p *ioC0Page) all() []uint8 {
+	return nil
+}
+
 func (p *ioC0Page) Poke(address uint8, value uint8) {
 	//fmt.Printf("Poke on $C0%02x with %02x ", address, value)
 	ss := p.softSwitchesW[address]

apple2/memoryManager.go

@@ -20,6 +20,7 @@ type memoryPage interface {
 	Peek(uint8) uint8
 	Poke(uint8, uint8)
 	internalPeek(uint8) uint8
+	all() []uint8
 }
 
 const (
@@ -43,6 +44,10 @@ func (mmu *memoryManager) internalPeek(address uint16) uint8 {
 	return mmu.activeMemory[hi].internalPeek(lo)
 }
 
+func (mmu *memoryManager) internalPage(hi uint8) []uint8 {
+	return mmu.activeMemory[hi].all()
+}
+
 // Poke sets the data at the given address
 func (mmu *memoryManager) Poke(address uint16, value uint8) {
 	if address == ioC8Off {

apple2/rxmPage.go

@@ -22,6 +22,10 @@ func (p *rxmPage) internalPeek(address uint8) uint8 {
 	return p.data[address]
 }
 
+func (p *rxmPage) all() []uint8 {
+	return p.data[:]
+}
+
 func (p *rxmPage) Poke(address uint8, value uint8) {
 	p.touch(address, true)
 	p.data[address] = value

apple2/screen.go

@@ -10,18 +10,29 @@ import (
 
 // Snapshot the currently visible screen
 func Snapshot(a *Apple2) *image.RGBA {
-	isTextMode := a.io.isSoftSwitchActive(ioFlagGraphics)
+	isTextMode := a.io.isSoftSwitchActive(ioFlagText)
 	is80ColMode := a.io.isSoftSwitchActive(ioFlag80Col)
+	isHiResMode := a.io.isSoftSwitchActive(ioFlagHiRes)
 	pageIndex := 0
 	if a.io.isSoftSwitchActive(ioFlagSecondPage) {
 		pageIndex = 1
 	}
 
-	if isTextMode && !is80ColMode {
+	if isTextMode {
-		//Text mode
+		if is80ColMode {
+			// Not supported
+		} else {
 			return snapshotTextMode(a, pageIndex)
 		}
-	fmt.Printf("t: %v, 8: %v\n", isTextMode, is80ColMode)
+	} else {
+		if isHiResMode {
+			return snapshotGraphMode(a, pageIndex)
+		} else {
+			// Not supported
+		}
+	}
+
+	//fmt.Printf("g: %v, 8: %v, h: %v\n", isTextMode, is80ColMode, isHiResMode)
 	return nil
 	//panic("Screen mode not supported")
 }
@@ -48,25 +59,35 @@ const (
 	charHeight        = 8
 	textColumns       = 40
 	textLines         = 24
-	textPage1Address = uint16(0x400)
+	textPage1Address  = uint16(0x0400)
-	textPage2Address = uint16(0x400)
+	textPage2Address  = uint16(0x0800)
+	graphWidth        = 280
+	graphHeight       = 192
+	graphPage1Address = uint16(0x2000)
+	graphPage2Address = uint16(0x4000)
 )
 
+func getTextCharOffset(col int, line int) uint16 {
+
+	// See "Understand the Apple II", page 5-10
+	// http://www.applelogic.org/files/UNDERSTANDINGTHEAII.pdf
+	section := line / 8 // Top, middle and bottom
+	eigth := line % 8
+	return uint16(section*40 + eigth*0x80 + col)
+}
+
 func getTextChar(a *Apple2, col int, line int, page int) uint8 {
 	address := textPage1Address
 	if page == 1 {
 		address = textPage2Address
 	}
-
+	address += getTextCharOffset(col, line)
-	// See "Understand the Apple II", page 5-10
-	// http://www.applelogic.org/files/UNDERSTANDINGTHEAII.pdf
-	section := line / 8 // Top, middle and bottom
-	eigth := line % 8
-	address += uint16(section*40 + eigth*0x80 + col)
 	return a.mmu.internalPeek(address)
 }
 
 func snapshotTextMode(a *Apple2, page int) *image.RGBA {
+	// TODO: Missing inverse and flash modes
+
 	width := textColumns * charWidth
 	height := textLines * charHeight
 	size := image.Rect(0, 0, width, height)
@@ -90,3 +111,51 @@ func snapshotTextMode(a *Apple2, page int) *image.RGBA {
 
 	return img
 }
+
+func getGraphLineOffset(line int) uint16 {
+
+	// See "Understand the Apple II", page 5-14
+	// http://www.applelogic.org/files/UNDERSTANDINGTHEAII.pdf
+	section := line >> 6 // Top, middle and bottom
+	outerEigth := (line >> 3) & 0x07
+	innerEigth := line & 0x07
+	return uint16(section*40 + outerEigth*0x80 + innerEigth*0x400)
+}
+
+func getGraphLine(a *Apple2, line int, page int) []uint8 {
+	address := graphPage1Address
+	if page == 1 {
+		address = graphPage2Address
+	}
+
+	address += getGraphLineOffset(line)
+	hi := uint8(address >> 8)
+	lo := uint8(address)
+
+	memPage := a.mmu.internalPage(hi)
+	//fmt.Printf("line: %v, lo: %x\n", line, lo)
+	return memPage[lo : lo+40]
+}
+
+func snapshotGraphMode(a *Apple2, page int) *image.RGBA {
+	size := image.Rect(0, 0, graphWidth, graphHeight)
+	img := image.NewRGBA(size)
+
+	for y := 0; y < graphHeight; y++ {
+		bytes := getGraphLine(a, y, page)
+		x := 0
+		for _, b := range bytes {
+			for j := uint(0); j < 7; j++ {
+				bit := (b >> j) & 1
+				colour := color.Black
+				if bit == 1 {
+					colour = color.White
+				}
+				img.Set(x, y, colour)
+				x++
+			}
+		}
+	}
+
+	return img
+}

apple2/screen_test.go

@@ -0,0 +1,24 @@
+package apple2
+
+import (
+	"testing"
+)
+
+func TestGetGraphLineOffest(t *testing.T) {
+	scenarios := map[int]uint16{
+		0:   0x2000,
+		1:   0x2400,
+		8:   0x2080,
+		63:  0x3f80,
+		64:  0x2028,
+		128: 0x2050,
+		191: 0x3fd0,
+	}
+
+	for in, want := range scenarios {
+		got := 0x2000 + getGraphLineOffset(in)
+		if want != got {
+			t.Errorf("expected %x but got %x for line %v", want, got, in)
+		}
+	}
+}

apple2/softSwitches2.go

@@ -3,7 +3,7 @@ package apple2
 const (
 	ioDataKeyboard uint8 = 0x10
 
-	ioFlagGraphics     uint8 = 0x50
+	ioFlagText         uint8 = 0x50
 	ioFlagMixed        uint8 = 0x52
 	ioFlagSecondPage   uint8 = 0x54
 	ioFlagHiRes        uint8 = 0x56
@@ -33,8 +33,8 @@ func addApple2SoftSwitches(io *ioC0Page) {
 	// for read and write. But the Apple2e take over some of them, with
 	// the prevention on acting only on writes.
 
-	io.addSoftSwitchRW(0x50, getSoftSwitch(ioFlagGraphics, false))
+	io.addSoftSwitchRW(0x50, getSoftSwitch(ioFlagText, false))
-	io.addSoftSwitchRW(0x51, getSoftSwitch(ioFlagGraphics, true))
+	io.addSoftSwitchRW(0x51, getSoftSwitch(ioFlagText, true))
 	io.addSoftSwitchRW(0x52, getSoftSwitch(ioFlagMixed, false))
 	io.addSoftSwitchRW(0x53, getSoftSwitch(ioFlagMixed, true))
 	io.addSoftSwitchRW(0x54, getSoftSwitch(ioFlagSecondPage, false))

apple2/unassignedPage.go

@@ -14,6 +14,10 @@ func (p *unassignedPage) internalPeek(address uint8) uint8 {
 	return 0xdd
 }
 
+func (p *unassignedPage) all() []uint8 {
+	return nil
+}
+
 func (p *unassignedPage) Poke(address uint8, value uint8) {
 	//fmt.Printf("Write on address 0x%02x%02x\n", p.page, address)
 	//panic(address)

apple2sdl/run.go

@@ -42,7 +42,8 @@ func SDLRun(a *apple2.Apple2) {
 			}
 		}
 
-		img := *apple2.Snapshot(a)
+		img := apple2.Snapshot(a)
+		if img != nil {
 			surface, err := sdl.CreateRGBSurfaceFrom(unsafe.Pointer(&img.Pix[0]), 40*7, 24*8, 32, 40*7*4,
 				0xff000000, 0x00ff0000, 0x0000ff00, 0x000000ff)
 			if err != nil {
@@ -61,7 +62,7 @@ func SDLRun(a *apple2.Apple2) {
 
 			surface.Free()
 			texture.Destroy()
-
+		}
 		sdl.Delay(1000 / 60)
 	}