izapple2/screenText.go

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package apple2
import (
"fmt"
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"image"
"image/color"
"strings"
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"time"
)
const (
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charWidth = 7
charHeight = 8
textColumns = 40
textLines = 24
textLinesMix = 4
textPage1Address = uint16(0x0400)
textPage2Address = uint16(0x0800)
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)
func getTextCharOffset(col int, line int) uint16 {
// See "Understanding 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)
return a.mmu.physicalMainRAM.subRange(address, address+1)[0]
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}
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func snapshotTextMode(a *Apple2, page int, mixMode bool, light color.Color) *image.RGBA {
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// Flash mode is 2Hz
isFlashedFrame := time.Now().Nanosecond() > (1 * 1000 * 1000 * 1000 / 2)
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lineStart := 0
if mixMode {
lineStart = textLines - textLinesMix
}
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width := textColumns * charWidth
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height := (textLines - lineStart) * charHeight
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size := image.Rect(0, 0, width, height)
img := image.NewRGBA(size)
for x := 0; x < width; x++ {
for y := 0; y < height; y++ {
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line := y/charHeight + lineStart
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col := x / charWidth
rowInChar := y % charHeight
colInChar := x % charWidth
char := getTextChar(a, col, line, page)
topBits := char >> 6
isInverse := topBits == 0
isFlash := topBits == 1
pixel := a.cg.getPixel(char, rowInChar, colInChar)
pixel = pixel != (isInverse || (isFlash && isFlashedFrame))
var colour color.Color
if pixel {
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colour = light
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} else {
colour = color.Black
}
img.Set(x, y, colour)
}
}
return img
}
// DumpTextModeAnsi returns the text mode contents using ANSI escape codes
// for reverse and flash
func DumpTextModeAnsi(a *Apple2) string {
content := "\n"
content += fmt.Sprintln(strings.Repeat("#", textColumns+4))
pageIndex := 0
if a.io.isSoftSwitchActive(ioFlagSecondPage) {
pageIndex = 1
}
isAltText := a.isApple2e && a.io.isSoftSwitchActive(ioFlagAltChar)
for l := 0; l < textLines; l++ {
line := ""
for c := 0; c < textColumns; c++ {
char := getTextChar(a, c, l, pageIndex)
line += textMemoryByteToString(char, isAltText)
}
content += fmt.Sprintf("# %v #\n", line)
}
content += fmt.Sprintln(strings.Repeat("#", textColumns+4))
return content
}
func textMemoryByteToString(value uint8, isAltCharSet bool) string {
// See https://en.wikipedia.org/wiki/Apple_II_character_set
// Supports the new lowercase characters in the Apple2e
// Only ascii from 0x20 to 0x5F is visible
topBits := value >> 6
isInverse := topBits == 0
isFlash := topBits == 1
if isFlash && isAltCharSet {
// On the Apple2e with lowercase chars there is not flash mode.
isFlash = false
isInverse = true
}
if isAltCharSet {
value = value & 0x7F
} else {
value = value & 0x3F
}
if value < 0x20 {
value += 0x40
}
if value == 0x7f {
// DEL is full box
value = '_'
}
if isFlash {
if value == ' ' {
// Flashing space in Apple is the full box. It can't be done with ANSI codes
value = '_'
}
return fmt.Sprintf("\033[5m%v\033[0m", string(value))
} else if isInverse {
return fmt.Sprintf("\033[7m%v\033[0m", string(value))
} else {
return string(value)
}
}