logic-gates/js/gates.js

// Gate evaluation and port geometry
import { GATE_W, GATE_H, PORT_R, gateInputCount, gateOutputCount } from './constants.js';
import { state } from './state.js';
import { recordSample } from './waveform.js';

export function getInputPorts(gate) {
    const count = gateInputCount(gate.type);
    const ports = [];
    for (let i = 0; i < count; i++) {
        const spacing = GATE_H / (count + 1);
        ports.push({ x: gate.x, y: gate.y + spacing * (i + 1), index: i, type: 'input' });
    }
    return ports;
}

export function getOutputPorts(gate) {
    const count = gateOutputCount(gate.type);
    const ports = [];
    for (let i = 0; i < count; i++) {
        ports.push({ x: gate.x + GATE_W, y: gate.y + GATE_H / 2, index: i, type: 'output' });
    }
    return ports;
}

export function evaluate(gate, visited = new Set()) {
    if (visited.has(gate.id)) return gate.value || 0;
    visited.add(gate.id);
    if (gate.type === 'INPUT' || gate.type === 'CLOCK') return gate.value;

    const inputCount = gateInputCount(gate.type);
    const inputs = [];
    for (let i = 0; i < inputCount; i++) {
        const conn = state.connections.find(c => c.to === gate.id && c.toPort === i);
        if (conn) {
            const srcGate = state.gates.find(g => g.id === conn.from);
            inputs.push(srcGate ? evaluate(srcGate, visited) : 0);
        } else {
            inputs.push(0);
        }
    }

    let result = 0;
    switch (gate.type) {
        case 'AND':    result = (inputs[0] && inputs[1]) ? 1 : 0; break;
        case 'OR':     result = (inputs[0] || inputs[1]) ? 1 : 0; break;
        case 'NOT':    result = inputs[0] ? 0 : 1; break;
        case 'NAND':   result = (inputs[0] && inputs[1]) ? 0 : 1; break;
        case 'NOR':    result = (inputs[0] || inputs[1]) ? 0 : 1; break;
        case 'XOR':    result = (inputs[0] !== inputs[1]) ? 1 : 0; break;
        case 'OUTPUT': result = inputs[0] || 0; break;
    }
    gate.value = result;
    return result;
}

export function evaluateAll() {
    state.gates.forEach(g => {
        if (g.type !== 'INPUT' && g.type !== 'CLOCK') g.value = 0;
    });
    state.gates.forEach(g => evaluate(g));
    if (state.recording && state.waveformVisible) recordSample();
}

export function findGateAt(x, y) {
    return state.gates.find(g => x >= g.x && x <= g.x + GATE_W && y >= g.y && y <= g.y + GATE_H);
}

export function findPortAt(x, y) {
    for (const gate of state.gates) {
        for (const p of getInputPorts(gate)) {
            if (Math.hypot(x - p.x, y - p.y) < PORT_R + 4) return { gate, index: p.index, type: 'input' };
        }
        for (const p of getOutputPorts(gate)) {
            if (Math.hypot(x - p.x, y - p.y) < PORT_R + 4) return { gate, index: p.index, type: 'output' };
        }
    }
    return null;
}