adc.js

"use strict";

export class Adc {
    constructor(sysvia, scheduler) {
        this.sysvia = sysvia;
        this.task = scheduler.newTask(this.onComplete.bind(this));
        this.status = 0x40;
        this.low = 0x00;
        this.high = 0x00;
    }

    read(addr) {
        switch (addr & 3) {
            case 0:
                return this.status;
            case 1:
                return this.high;
            case 2:
                return this.low;
            default:
                break;
        }
        return 0x40;
    }

    write(addr, val) {
        if ((addr & 3) !== 0) return;
        // 8 bit conversion takes 4ms whereas 10 bit conversions take 10ms, according to AUG
        this.task.cancel();
        this.task.schedule(val & 0x08 ? 20000 : 8000);
        this.status = (val & 0x0f) | 0x80;
        this.sysvia.setcb1(true);
    }

    onComplete() {
        let val = 0x8000;

        const pads = this.sysvia.getGamepads();
        if (pads && pads[0]) {
            const pad = pads[0];
            const pad2 = pads[1];

            let rawValue = 0;

            const stick = Math.floor(this.status & 0x03);

            switch (stick) {
                default:
                case 0:
                    rawValue = pad.axes[0];
                    break;
                case 1:
                    rawValue = pad.axes[1];
                    break;
                case 2:
                    if (pad2) {
                        rawValue = pad2.axes[0];
                    } else {
                        rawValue = pad.axes[2];
                    }
                    break;
                case 3:
                    if (pad2) {
                        rawValue = pad2.axes[1];
                    } else {
                        rawValue = pad.axes[3];
                    }
                    break;
            }

            // scale from [1,-1] to [0,0xffff]
            val = Math.floor(((1 - rawValue) / 2) * 0xffff);
        }
        this.status = (this.status & 0x0f) | 0x40 | ((val >>> 10) & 0x03);
        this.low = val & 0xff;
        this.high = (val >>> 8) & 0xff;
        this.sysvia.setcb1(false);
    }
}