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https://github.com/bradford-hamilton/apple-1.git
synced 2024-06-11 08:29:35 +00:00
cdca8f735d
Still a little iffy on the code design, although this seems like it could be a desirable pattern. This way I would have to write an opcode handler for all the cases and register it to the “op”. That way step calls are super simple from Appleone’s point of view -> get the operation and that operation has everything needed to execute on the vm.
61 lines
1.2 KiB
Go
61 lines
1.2 KiB
Go
package vm
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import (
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"fmt"
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)
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// Appleone represents the virtual Apple 1 computer
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type Appleone struct {
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cpu *Mos6502 // virtual mos6502 cpu
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mem block // available memory (64kiB)
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}
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// New returns a pointer to an initialized Appleone with a brand spankin new CPU
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func New() *Appleone {
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return &Appleone{
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cpu: newCPU(),
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mem: newBlock(),
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}
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}
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func (a *Appleone) load(addr uint16, data []uint8) {
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a.mem.load(addr, data)
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a.cpu.pc = addr
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}
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func (a *Appleone) step() {
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op, err := opByCode(a.mem[a.cpu.pc])
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if err != nil {
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fmt.Println("TODO")
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}
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a.cpu.pc += uint16(op.size)
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if err := op.exec(a, op); err != nil {
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fmt.Println("TODO")
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}
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}
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func (a *Appleone) pushWordToStack(data byte) {
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a.mem[StackBottom+uint16(a.cpu.sp)] = data
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a.cpu.sp = uint8((uint16(a.cpu.sp) - 1) & 0xFF)
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}
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func (a *Appleone) pushDWordToStack(data uint16) {
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h := uint8((data >> 8) & 0xFF)
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l := uint8(data & 0xFF)
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a.pushWordToStack(h)
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a.pushWordToStack(l)
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}
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func (a *Appleone) popStackWord() uint8 {
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a.cpu.sp = uint8((uint16(a.cpu.sp) + 1) & 0xFF)
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return a.mem[StackBottom+uint16(a.cpu.sp)]
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}
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func (a *Appleone) popStackDWord() uint16 {
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l := a.popStackWord()
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h := a.popStackWord()
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return (uint16(h) << 8) | uint16(l)
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}
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