diff options
Diffstat (limited to '65c02.ts')
| -rw-r--r-- | 65c02.ts | 220 |
1 files changed, 218 insertions, 2 deletions
diff --git a/65c02.ts b/65c02.ts index a7660b4..96207a3 100644 --- a/65c02.ts +++ b/65c02.ts @@ -1,8 +1,13 @@ -class BitField { +import opcodeMatrix from "./opcode_matrix.json" with { type: "json" }; + +export class BitField { bits: boolean[]; flip(bit: number) { this.bits[bit] = !this.bits[bit]; } + bit(bit: number) { + return this.bits[bit] + } setBit(bit: number, value: boolean) { this.bits[bit] = value; } @@ -26,6 +31,217 @@ class BitField { } } +export class Register<T=number> extends BitField { + get value(): number { + return this.num() + } + set value(value: number) { + this.set(value) + } + increment(): number { + this.set(this.num() + 1); + return this.num() + } + decrement(): number { + this.set(this.num() - 1); + return this.num() + } + constructor(bits: number) { + super(bits); + } +} + +export class Pin { + high: boolean = false; + HI() { + this.high = true + } + LO() { + this.high = false + } + constructor(init = false) { + this.high = init + } +} + +export class IO { + data: BitField = new BitField(8); + address: BitField = new BitField(16); + busEnable: Pin = new Pin(); + NMI: Pin = new Pin(); + ready: Pin = new Pin(true); + reset: Pin = new Pin(true); + readWrite: Pin = new Pin(); + interruptRequest: Pin = new Pin(); +} + +/** + * the shittiest 65c02 emulator ever + * + * not clock cycle accurate because fuck you + */ export default class The65c02 { - data: BitField = new BitField(8) + io: IO = new IO(); + //SECTION - register + programCounter: Register<16> = new Register(16); + regA: Register<8> = new Register(8); + regX: Register<8> = new Register(8); + regY: Register<8> = new Register(8); + + stackPointer: Register<8> = new Register(8); + status: Register<8> = new Register(8); + //!SECTION + //SECTION - status reg bits + get carry(): boolean {return this.status.bit(0)} + set carry(value:boolean) {this.status.setBit(0, value)} + get zero(): boolean {return this.status.bit(1)} + set zero(value:boolean) {this.status.setBit(1, value)} + get IRQBDisable(): boolean {return this.status.bit(2)} + set IRQBDisable(value:boolean) {this.status.setBit(2, value)} + get decimalMode(): boolean {return this.status.bit(3)} + set decimalMode(value:boolean) {this.status.setBit(3, value)} + get BRK(): boolean {return this.status.bit(4)} + set BRK(value:boolean) {this.status.setBit(4, value)} + // ...1... // + get overflow(): boolean {return this.status.bit(6)} + set overflow(value:boolean) {this.status.setBit(6, value)} + get negative(): boolean {return this.status.bit(7)} + set negative(value:boolean) {this.status.setBit(7, value)} + //!SECTION + read: () => void; + write: () => void; + readPC(): BitField { + this.io.address = this.programCounter; + this.read() + return this.io.data; + } + flagZN(num: number) { + this.negative = (num & 0x80) != 0; + this.zero = num == 0; + } + flagZCN(num: number) { + this.carry = num > 0xFF + this.negative = (num & 0x80) != 0; + this.zero = num == 0; + } + instructions: Record<string, (mode: string) => void> = {}; + cycle() { + if(!this.io.reset.high) { + // reset register thingies + this.IRQBDisable = true; + this.decimalMode = false; + this.BRK = true; + // get reset vector + let resetVector = 0; + this.io.address.set(0xFFFC); + this.read() + resetVector |= this.io.data.num(); + this.io.address.set(0xFFFD); + this.read() + resetVector |= this.io.data.num() << 8; + // move PC to RV + this.programCounter.set(resetVector) + } + this.io.address.set(this.programCounter.num()); + this.read(); + const instruction = this.io.data + .num() + .toString(16) + .padStart(2, '0') + .toLowerCase(); + const opm: Record<string, { mnemonic: string, mode: string }> = opcodeMatrix; + if (!opm[instruction]) + throw `not found ${instruction}` + if (!this.instructions[opm[instruction].mnemonic]) + throw `not implement, sowwy (${opm[instruction].mnemonic}.ts not found)`; + console.debug(opm[instruction].mnemonic, opm[instruction].mode) + this.instructions[opm[instruction].mnemonic].call(this, opm[instruction].mode); + } + //SECTION - utils + getZPAddr(): number { + this.programCounter.increment() + const zp = this.readPC().num() + return zp + } + getZPXAddr(): number { + this.programCounter.increment() + const zp = this.readPC().num() + return (this.regX.num() + zp) & 0xFF + } + getAbsoluteAddr(): number { + this.programCounter.increment() + const lo_abit = this.readPC().num() + this.programCounter.increment() + const hi_abit = this.readPC().num() + return (hi_abit << 8) | lo_abit + } + getAbsoluteXAddr(): number { + this.programCounter.increment() + const lo_abit = this.readPC().num() + this.programCounter.increment() + const hi_abit = this.readPC().num() + return this.regX.num() + ((hi_abit << 8) | lo_abit) + } + getAbsoluteYAddr(): number { + this.programCounter.increment() + const lo_abit = this.readPC().num() + this.programCounter.increment() + const hi_abit = this.readPC().num() + return this.regX.num() + ((hi_abit << 8) | lo_abit) + } + getIndirectXAddr(): number { + this.programCounter.increment() + const addr = this.readPC().num() + this.io.address.set((this.regX.num() + addr) & 0xFF) + const lo_abit = this.readPC().num() + this.io.address.set((this.regX.num() + addr + 1) & 0xFF) + const hi_abit = this.readPC().num() + return ((hi_abit << 8) | lo_abit) + } + getIndirectYAddr(): number { + this.programCounter.increment() + const addr = this.readPC().num() + this.io.address.set((addr) & 0xFF) + const lo_abit = this.readPC().num() + this.io.address.set((addr + 1) & 0xFF) + const hi_abit = this.readPC().num() + return ((hi_abit << 8) | lo_abit) + this.regY.num(); + } + getAddr(mode: string): number { + switch (mode) { + case 'immediate': + this.programCounter.increment() + this.programCounter.increment() + return this.programCounter.num() - 1 + case 'zero-page': + return this.getZPAddr() + case 'zero-page, X-indexed': + return this.getZPXAddr() + case 'absolute': + return this.getAbsoluteAddr() + case 'absolute, X-indexed': + return this.getAbsoluteXAddr() + case 'absolute, Y-indexed': + return this.getAbsoluteYAddr() + case 'indirect, Y-indexed': + return this.getIndirectYAddr() + case 'X-indexed, indirect': + return this.getIndirectXAddr() + + default: + throw 'unknown mode '+mode + } + } + //!SECTION + constructor (read: () => void, write: () => void) { + this.read = read; + this.write = write; + } + async loadInstructions() { + const dir = Deno.readDirSync('instructions') + for (const entry of dir) { + this.instructions[entry.name.replace('.ts', '')] + = (await import(`./instructions/${entry.name}`)).default + } + } } \ No newline at end of file |