Support double width high resolution

README.md

@@ -12,6 +12,7 @@ Portable emulator of an Apple II+. Written in Go.
     - Apple //e enhanced with 128Kb of RAM
     - Base64A clone with 48Kb of base RAM and paginated ROM
 - Sound
+- Storage
     - 16 Sector diskettes in DSK format
     - ProDos hard disk
 - Emulated extension cards:
@@ -27,6 +28,7 @@ Portable emulator of an Apple II+. Written in Go.
     - Low-Resolution graphics
     - Double-Width Low-Resolution graphics (Apple //e only)
     - High-Resolution graphics
+    - Double-Width High-Resolution graphics (Apple //e only)
     - Mixed mode
 - Displays:
     - Green monochrome monitor with half width pixel support

screen.go

@@ -22,14 +22,9 @@ func Snapshot(a *Apple2) *image.RGBA {
 	isHiResMode := a.io.isSoftSwitchActive(ioFlagHiRes)
 	isMixMode := a.io.isSoftSwitchActive(ioFlagMixed)
 	is80Columns := a.io.isSoftSwitchActive(ioFlag80Col)
-	isDoubleResMode := !isTextMode && is80Columns && a.io.isSoftSwitchActive(ioFlagAnnunciator3)
+	isDoubleResMode := !isTextMode && is80Columns && !a.io.isSoftSwitchActive(ioFlagAnnunciator3)
 	isSecondPage := a.io.isSoftSwitchActive(ioFlagSecondPage) && !a.mmu.store80Active
 
-	pageIndex := 0
-	if isSecondPage {
-		pageIndex = 1
-	}
-
 	var lightColor color.Color
 	if isColor {
 		lightColor = color.White
@@ -45,7 +40,11 @@ func Snapshot(a *Apple2) *image.RGBA {
 		snap = snapshotTextMode(a, is80Columns, isSecondPage, false /*isMixMode*/, lightColor)
 	} else {
 		if isHiResMode {
-			snap = snapshotHiResModeMonoShift(a, pageIndex, isMixMode, lightColor)
+			if isDoubleResMode {
+				snap = snapshotDoubleHiResModeMono(a, isSecondPage, isMixMode, lightColor)
+			} else {
+				snap = snapshotHiResModeMono(a, isSecondPage, isMixMode, lightColor)
+			}
 		} else {
 			snap = snapshotLoResModeMono(a, isDoubleResMode, isSecondPage, isMixMode, lightColor)
 		}

screenHiRes.go

@@ -7,6 +7,8 @@ import (
 
 const (
 	hiResWidth        = 280
+	hiResLineBytes    = hiResWidth / 7
+	doubleHiResWidth  = 2 * hiResWidth
 	hiResHeight       = 192
 	hiResHeightMixed  = 160
 	hiResPage1Address = uint16(0x2000)
@@ -23,17 +25,17 @@ func getHiResLineOffset(line int) uint16 {
 	return uint16(section*40 + outerEigth*0x80 + innerEigth*0x400)
 }
 
-func getHiResLine(a *Apple2, line int, page int) []uint8 {
+func getHiResLine(a *Apple2, line int, isSecondPage bool, auxMem bool) []uint8 {
 	address := hiResPage1Address
-	if page == 1 {
+	if isSecondPage {
 		address = hiResPage2Address
 	}
 
 	address += getHiResLineOffset(line)
-	return a.mmu.physicalMainRAM.subRange(address, address+40)
+	return a.mmu.getPhysicalMainRAM(auxMem).subRange(address, address+hiResLineBytes)
 }
 
-func snapshotHiResModeMonoShift(a *Apple2, page int, mixedMode bool, light color.Color) *image.RGBA {
+func snapshotHiResModeMono(a *Apple2, isSecondPage bool, mixedMode bool, light color.Color) *image.RGBA {
 	// As described in "Undertanding the Apple II", with half pixel shifts
 
 	height := hiResHeight
@@ -45,7 +47,7 @@ func snapshotHiResModeMonoShift(a *Apple2, page int, mixedMode bool, light color
 	img := image.NewRGBA(size)
 
 	for y := 0; y < height; y++ {
-		bytes := getHiResLine(a, y, page)
+		bytes := getHiResLine(a, y, isSecondPage, false /*auxMem*/)
 		x := 0
 		var previousColour color.Color = color.Black
 		for _, b := range bytes {
@@ -71,116 +73,39 @@ func snapshotHiResModeMonoShift(a *Apple2, page int, mixedMode bool, light color
 	return img
 }
 
-func snapshotHiResModeReferenceColor(a *Apple2, page int, mixedMode bool) *image.RGBA {
+func snapshotDoubleHiResModeMono(a *Apple2, isSecondPage bool, mixedMode bool, light color.Color) *image.RGBA {
-	// As defined on "Apple II Reference Manual", page 19
+	// As described in "Inside the Apple IIe"
 
 	height := hiResHeight
 	if mixedMode {
 		height = hiResHeightMixed
 	}
 
-	size := image.Rect(0, 0, hiResWidth, height)
+	size := image.Rect(0, 0, doubleHiResWidth, height)
 	img := image.NewRGBA(size)
-
-	// RGB values from https://mrob.com/pub/xapple2/colors.html
-	black := color.RGBA{0, 0, 0, 255}
-	violet := color.RGBA{255, 68, 253, 255}
-	red := color.RGBA{255, 106, 60, 255}
-	green := color.RGBA{20, 246, 60, 255}
-	blue := color.RGBA{20, 207, 253, 255}
-	white := color.RGBA{255, 255, 255, 255}
-	colorMap := [][][]color.Color{
-		{
-			/* 00 */ {black, black},
-			/* 01 */ {black, green},
-			/* 10 */ {violet, black},
-			/* 11 */ {white, white},
-		},
-		{
-			/* 00 */ {black, black},
-			/* 01 */ {black, red},
-			/* 10 */ {blue, black},
-			/* 11 */ {white, white},
-		},
-	}
-
 	for y := 0; y < height; y++ {
-		bytes := getHiResLine(a, y, page)
+		lineParts := [][]uint8{
+			getHiResLine(a, y, isSecondPage, true),
+			getHiResLine(a, y, isSecondPage, false),
+		}
 		x := 0
-		previous := uint8(0)
+		// For the NTSC filter to work we have to insert an initial black pixel and skip the last one
-		for _, b := range bytes {
+		img.Set(x, y, color.Black)
-			shift := b >> 7
+		x++
+		for iByte := 0; iByte < hiResLineBytes-1; iByte++ {
+			for iPart := 0; iPart < 2; iPart++ {
+				b := lineParts[iPart][iByte]
 				for j := uint(0); j < 7; j++ {
 					bit := (b >> j) & 1
-				even := x%2 == 0
+					colour := light
-				if even {
+					if bit == 0 {
-					previous = bit
+						colour = color.Black
-				} else {
-					pair := colorMap[shift][(previous<<1)+bit]
-					img.Set(x-1, y, pair[0])
-					img.Set(x, y, pair[1])
 					}
+					img.Set(x, y, colour)
 					x++
 				}
 			}
 		}
-
+	}
-	return img
-}
-
-func snapshotHiResModeReferenceColorSolid(a *Apple2, page int, mixedMode bool) *image.RGBA {
-	// As defined on "Apple II Reference Manual", page 19
-	// but with more solid colors and half the resolution
-
-	height := hiResHeight
-	if mixedMode {
-		height = hiResHeightMixed
-	}
-
-	size := image.Rect(0, 0, hiResWidth/2, height)
-	img := image.NewRGBA(size)
-
-	// RGB values from https://mrob.com/pub/xapple2/colors.html
-	black := color.RGBA{0, 0, 0, 255}
-	violet := color.RGBA{255, 68, 253, 255}
-	red := color.RGBA{255, 106, 60, 255}
-	green := color.RGBA{20, 246, 60, 255}
-	blue := color.RGBA{20, 207, 253, 255}
-	white := color.RGBA{255, 255, 255, 255}
-	colorMap := [][]color.Color{
-		{
-			/* 00 */ black,
-			/* 01 */ green,
-			/* 10 */ violet,
-			/* 11 */ white,
-		},
-		{
-			/* 00 */ black,
-			/* 01 */ red,
-			/* 10 */ blue,
-			/* 11 */ white,
-		},
-	}
-
-	for y := 0; y < height; y++ {
-		bytes := getHiResLine(a, y, page)
-		x := 0
-		previous := uint8(0)
-		for _, b := range bytes {
-			shift := b >> 7
-			for j := uint(0); j < 7; j++ {
-				bit := (b >> j) & 1
-				even := x%2 == 0
-				if even {
-					previous = bit
-				} else {
-					colour := colorMap[shift][(previous<<1)+bit]
-					img.Set(x/2, y, colour)
-				}
-				x++
-			}
-		}
-	}
-
 	return img
 }

screenNtscFilter.go

@@ -62,7 +62,7 @@ func filterNTSCColor(blacker bool, in *image.RGBA) *image.RGBA {
 	out := image.NewRGBA(size)
 
 	for y := b.Min.Y; y < b.Max.Y; y++ {
-		// We store the last four bits. We start will 0000
+		// We store the last four bits. We start with 0000
 		v := 0
 		for x := b.Min.X; x < b.Dx(); x++ {
 			cIn := in.At(x, y)