Run results for: Pack array of bitmasks (numbers)

Test name	Executions per second
✓ UnPack	55,426,756 Ops/sec
UnPack (Optimized)	13,106,546 Ops/sec
Pack (Optimized)	2,914,746 Ops/sec
Pack	391,370 Ops/sec

Script Preparation code:

function generateRandomBitmasks(count = 100) {
    const bitmasks = new Array(count);
    for (let i = 0; i < count; i++) {
        let bitLength = Math.floor(Math.random() * (32 - 5 + 1)) + 5;
        bitmasks[i] = Math.floor(Math.random() * (1 << bitLength));
    }
    return bitmasks;
}

var bitmasks = generateRandomBitmasks();
var packed = packBitmasks(bitmasks);
var packedV8 = packBitmasksV8(bitmasks);

function packBitmasks(bitmasks) {
    let totalBits = bitmasks.length * 32;
    let packedSize = Math.ceil(totalBits / 8);
    let packed = new Uint8Array(packedSize);
    
    let bitIndex = 0;

    for (let i = 0; i < bitmasks.length; i++) {
        let value = bitmasks[i];

        for (let b = 0; b < 32; b++) {
            if (bitIndex >= totalBits) break;
            let bytePos = bitIndex >> 3;
            let bitPos = bitIndex % 8;
            if (value & (1 << b)) {
                packed[bytePos] |= (1 << bitPos);
            }
            bitIndex++;
        }
    }

    return packed;
}

function unpackBitmasks(packed, length) {
    let bitmasks = new Uint32Array(length);
    let bitIndex = 0;

    for (let i = 0; i < length; i++) {
        let value = 0;
        for (let b = 0; b < 32; b++) {
            if (bitIndex >= packed.length * 8) break;
            let bytePos = bitIndex >> 3;
            let bitPos = bitIndex % 8;
            if (packed[bytePos] & (1 << bitPos)) {
                value |= (1 << b);
            }
            bitIndex++;
        }
        bitmasks[i] = value;
    }

    return bitmasks;
}

function packBitmasksV8(bitmasks) {
    let packed = new Uint8Array(bitmasks.length * 4);
    let packedView = new Uint32Array(packed.buffer);

    for (let i = 0, len = bitmasks.length; i < len; i++) {
        packedView[i] = bitmasks[i];
    }

    return packed;
}

function unpackBitmasksV8(packed) {
    let packedView = new Uint32Array(packed.buffer);
    let bitmasks = new Array(packedView.length);

    for (let i = 0, len = packedView.length; i < len; i++) {
        bitmasks[i] = packedView[i];
    }

    return bitmasks;
}

Run results for: Pack array of bitmasks (numbers)

Pack

UnPack

Pack (Optimized)

UnPack (Optimized)