zx-generation/src/utils/debugger.js

A high-fidelity ZX Spectrum emulator in JavaScript — fully generated by a large language model (LLM) to explore the boundaries of AI in systems programming.

/**
 * Z80 Debugger
 * Simple debugging utilities for the emulator
 */
class Z80Debugger {
    constructor(cpu) {
        this.cpu = cpu;
        this.breakpoints = new Set();
        this.history = [];
        this.historySize = 100;
    }

    /**
     * Add a breakpoint at the specified address
     */
    addBreakpoint(address) {
        this.breakpoints.add(address & 0xffff);
    }

    /**
     * Remove a breakpoint
     */
    removeBreakpoint(address) {
        this.breakpoints.delete(address & 0xffff);
    }

    /**
     * Execute one instruction with debugging
     */
    step() {
        const pc = this.cpu.registers.getPC();

        // Check breakpoint
        if (this.breakpoints.has(pc)) {
            console.log(`Breakpoint hit at ${pc.toString(16).padStart(4, '0').toUpperCase()}H`);
            return false;
        }

        // Save state to history
        this.saveState();

        // Execute instruction
        this.cpu.execute();

        return true;
    }

    /**
     * Save current CPU state to history
     */
    saveState() {
        const state = {
            pc: this.cpu.registers.getPC(),
            registers: { ...this.cpu.registers.data },
            flags: this.cpu.registers.get('F'),
            cycles: this.cpu.cycles,
        };

        this.history.push(state);
        if (this.history.length > this.historySize) {
            this.history.shift();
        }
    }

    /**
     * Print current CPU state
     */
    printState() {
        const regs = this.cpu.registers;
        const flags = this.cpu.flags;
        const f = regs.get('F');

        console.log('\n--- CPU State ---');
        console.log(
            `PC: ${regs.getPC().toString(16).padStart(4, '0').toUpperCase()}H  SP: ${regs.get16('SP').toString(16).padStart(4, '0').toUpperCase()}H`
        );
        console.log(
            `AF: ${regs.getAF().toString(16).padStart(4, '0').toUpperCase()}H  BC: ${regs.getBC().toString(16).padStart(4, '0').toUpperCase()}H  DE: ${regs.getDE().toString(16).padStart(4, '0').toUpperCase()}H  HL: ${regs.getHL().toString(16).padStart(4, '0').toUpperCase()}H`
        );
        console.log(
            `IX: ${regs.get16('IX').toString(16).padStart(4, '0').toUpperCase()}H  IY: ${regs.get16('IY').toString(16).padStart(4, '0').toUpperCase()}H  I: ${regs.get('I').toString(16).padStart(2, '0').toUpperCase()}H  R: ${regs.get('R').toString(16).padStart(2, '0').toUpperCase()}H`
        );

        const flagStr = [
            flags.getFlag(f, flags.masks.S) ? 'S' : '-',
            flags.getFlag(f, flags.masks.Z) ? 'Z' : '-',
            flags.getFlag(f, flags.masks.F5) ? '5' : '-',
            flags.getFlag(f, flags.masks.H) ? 'H' : '-',
            flags.getFlag(f, flags.masks.F3) ? '3' : '-',
            flags.getFlag(f, flags.masks.PV) ? 'P' : '-',
            flags.getFlag(f, flags.masks.N) ? 'N' : '-',
            flags.getFlag(f, flags.masks.C) ? 'C' : '-',
        ].join('');

        console.log(`Flags: ${flagStr}  Cycles: ${this.cpu.cycles}`);
    }

    /**
     * Show memory dump
     */
    memoryDump(address, lines = 8) {
        console.log(
            `\n--- Memory Dump from ${address.toString(16).padStart(4, '0').toUpperCase()}H ---`
        );

        for (let i = 0; i < lines; i++) {
            const addr = (address + i * 16) & 0xffff;
            const bytes = [];
            const chars = [];

            for (let j = 0; j < 16; j++) {
                const byte = this.cpu.memory.readByte(addr + j);
                bytes.push(byte.toString(16).padStart(2, '0').toUpperCase());
                chars.push(byte >= 32 && byte <= 126 ? String.fromCharCode(byte) : '.');
            }

            console.log(
                `${addr.toString(16).padStart(4, '0').toUpperCase()}H: ${bytes.join(' ')}  ${chars.join('')}`
            );
        }
    }
}

export { Z80Debugger };