120 lines
2.7 KiB
Go
120 lines
2.7 KiB
Go
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package apple2
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import (
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"image"
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)
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const (
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loResPixelWidth = charWidth
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loResPixelHeight = charHeight / 2
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loResWidth = textColumns
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loResHeight = textLines * 2
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loResHeightMixed = (textLines - textLinesMix) * 2
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loRes
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loResPage1Address = textPage1Address
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loResPage2Address = textPage2Address
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)
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func snapshotLoResModeReferenceColor(a *Apple2, page int, mixedMode bool) *image.RGBA {
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// As defined on "Apple II Reference Manual"
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height := loResHeight
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if mixedMode {
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height = loResHeightMixed
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}
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size := image.Rect(0, 0, loResWidth, height)
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img := image.NewRGBA(size)
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// Lores colors correspond to the NTSC 4 bit patterns reversed
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colorMap := getNTSCColorMap()
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reversedNibble := []uint8{0, 8, 4, 12, 2, 10, 6, 14, 1, 9, 5, 13, 3, 11, 7, 15}
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for y := 0; y < height; y = y + 2 {
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for x := 0; x < loResWidth; x++ {
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// Each text mode char encodes two pixels
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char := getTextChar(a, x, y/2, page)
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bottom := char >> 4
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top := char & 0xf
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img.Set(x, y, colorMap[reversedNibble[top]])
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img.Set(x, y+1, colorMap[reversedNibble[bottom]])
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}
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}
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return img
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}
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/*
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func getLoResLine(a *Apple2, line int, page int) []uint8 {
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address := loResPage1Address
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if page == 1 {
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address = loResPage2Address
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}
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// Every text line encodes two lores lines
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address += getTextCharOffset(0, line/2)
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data := make([]uint8, 0, textColumns)
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lower := (line % 2) == 1
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for i := uint16(0); i < textColumns; i++ {
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// Two pixels are encoded on each text page char position
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v := a.mmu.internalPeek(address + i)
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if lower {
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// The four nost significant bits store the odd lines
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v >>= 4
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} else {
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// The four least significant bits store the even lines
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v &= 0xf
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}
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data = append(data)
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}
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return data
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}
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func snapshotLoResModeMonoShift(a *Apple2, page int, mixedMode bool, light color.Color) *image.RGBA {
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// As described in "Undertanding the Apple II", with half pixel shifts
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height := loResHeight
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if mixedMode {
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height = loResHeightMixed
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}
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size := image.Rect(0, 0, 2*loResWidth*loResPixelWidth, height*loResPixelHeight)
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img := image.NewRGBA(size)
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for y := 0; y < height; y++ {
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bytes := getLoResLine(a, y, page)
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x := 0
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for i, v := range bytes {
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// For each loRes 4bit pixel we have to complete 7*2 half mono pixels
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for j := 0; j < 14; i++ {
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}
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}
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x := 0
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var previousColour color.Color = color.Black
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for _, b := range bytes {
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shifted := b>>7 == 1
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for j := uint(0); j < 7; j++ {
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bit := (b >> j) & 1
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colour := light
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if bit == 0 {
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colour = color.Black
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}
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if shifted {
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img.Set(x, y, previousColour)
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} else {
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img.Set(x, y, colour)
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}
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img.Set(x+1, y, colour)
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previousColour = colour
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x += 2
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}
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}
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}
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return img
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}
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*/
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