78 lines
1.5 KiB
Go
78 lines
1.5 KiB
Go
package goapple2
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import (
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"github.com/zellyn/go6502/cpu"
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"github.com/zellyn/goapple2/videoscan"
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)
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// Memory for the tests. Satisfies the cpu.Memory interface.
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type Apple2 struct {
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mem [65536]byte
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cpu cpu.Cpu
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key byte // BUG(zellyn): make reads/writes atomic
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keys chan byte
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plotter videoscan.Plotter
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scanner *videoscan.Scanner
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}
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// Cycle counter. Satisfies the cpu.Ticker interface.
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type CycleCount uint64
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func (c *CycleCount) Tick() {
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*c += 1
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}
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func NewApple2(p videoscan.Plotter, rom []byte) *Apple2 {
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var cc CycleCount
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a2 := Apple2{
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keys: make(chan byte, 16),
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}
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copy(a2.mem[len(a2.mem)-len(rom):len(a2.mem)], rom)
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a2.scanner = videoscan.NewScanner(&a2, p, [2048]byte{})
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a2.cpu = cpu.NewCPU(&a2, &cc, cpu.VERSION_6502)
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a2.cpu.Reset()
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return &a2
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}
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func (a2 *Apple2) Read(address uint16) byte {
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// Keyboard read
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if address == 0xC000 {
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if a2.key&0x80 == 0 {
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select {
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case key := <-a2.keys:
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a2.key = key
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default:
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}
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}
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return a2.key
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}
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if address == 0xC010 {
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a2.key &= 0x7F
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return 0 // BUG(zellyn): return proper value (keydown on IIe, not sure on II+)
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}
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return a2.mem[address]
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}
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func (a2 *Apple2) Write(address uint16, value byte) {
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if address >= 0xD000 {
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return
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}
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if address == 0xC010 {
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// Clear keyboard strobe
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a2.key &= 0x7F
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}
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a2.mem[address] = value
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}
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func (a2 *Apple2) Keypress(key byte) {
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a2.keys <- key
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}
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func (a2 *Apple2) Step() error {
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if err := a2.cpu.Step(); err != nil {
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return err
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}
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a2.scanner.Scan1()
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return nil
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}
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