99 lines
2.0 KiB
Go
99 lines
2.0 KiB
Go
package apple2
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import "fmt"
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type textPages struct {
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pages [4]textPage
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}
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type textPage struct {
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dirty bool
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data [256]uint8
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}
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func (p *textPage) Peek(address uint8) uint8 {
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return p.data[address]
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}
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func (p *textPage) Poke(address uint8, value uint8) {
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p.data[address] = value
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// Note: we could avoid setting dirty on the 16 blocks of 8 hidden bytes
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p.dirty = true
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}
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func textMemoryByteToString(value uint8) string {
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value = value & 0x7F
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if value < ' ' {
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return "@"
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}
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return string(value)
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}
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func textMemoryByteToStringHex(value uint8) string {
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return fmt.Sprintf("%02x ", value)
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}
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func (tp *textPages) prepare() {
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fmt.Printf("\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n")
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}
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func (tp *textPages) dump() {
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// See "Understand the Apple II", page 5-10
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// http://www.applelogic.org/files/UNDERSTANDINGTHEAII.pdf
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fmt.Print("\033[26A")
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fmt.Println("------------------------------------------")
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var i, j, h uint8
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// Top, middle and botton screen
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for i = 0; i < 120; i = i + 40 {
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// Memory pages
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for _, p := range tp.pages {
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// The two half pages
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for _, h = range []uint8{0, 128} {
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line := ""
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for j = i + h; j < i+h+40; j++ {
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line += textMemoryByteToString(p.Peek(j))
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}
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fmt.Printf("| %v |\n", line)
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}
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}
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}
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fmt.Println("------------------------------------------")
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}
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func (tp *textPages) dumpIfDirty() {
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dirty := false
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for i := 0; i < 4; i++ {
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if tp.pages[i].dirty {
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dirty = true
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tp.pages[i].dirty = false
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}
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}
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if !dirty {
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return
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}
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tp.dump()
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}
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func (tp *textPages) charAddress(column uint8, line uint8) (page uint8, address uint8) {
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page = (line % 8) / 2
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address = column + (line/8)*40 + (line%2)*128
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return
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}
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func (tp *textPages) read(column uint8, line uint8) uint8 {
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page, address := tp.charAddress(column, line)
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return tp.pages[page].Peek(address)
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}
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func (tp *textPages) write(column uint8, line uint8, value uint8) {
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page, address := tp.charAddress(column, line)
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tp.pages[page].Poke(address, value)
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}
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