Run results for: unbiased ranged random integer generation functions

Test name	Executions per second
✓ Old rejection sampling	265,496 Ops/sec
Multiply shift random BigInt	226,335 Ops/sec
Multiply shift random int32	30,163 Ops/sec

Classic 16

if ((bound & -bound) === bound) {
    window.crypto.getRandomValues(ta16);
    return bound * ta16[0] >>> 16;
}
const limit = 65536 - 65536 % bound;
do {
    window.crypto.getRandomValues(ta16);
} while (ta16[0] >= limit);
return ta16[0] % bound;

Mul shf 16

if ((bound & -bound) === bound) {
    window.crypto.getRandomValues(ta16);
    return bound * ta16[0] >>> 16;
}
const limit = (-bound >>> 0) % bound;
let value;
do {
    window.crypto.getRandomValues(ta16);
    value = ta16[0] * bound;
} while ((value & 65535) < limit);
return value >>> 16;

Imul shf 16

if ((bound & -bound) === bound) {
    window.crypto.getRandomValues(ta16);
    return bound * ta16[0] >>> 16;
}
const limit = (-bound >>> 0) % bound;
let value;
do {
    window.crypto.getRandomValues(ta16);
    value = Math.imul(ta16[0], bound);
} while ((value & 65535) < limit);
return value >>> 16;

Classic int

if ((bound & -bound) === bound) {
    window.crypto.getRandomValues(ta32);
    return ta32[0] * bound / 4294967296 >>> 0;
}
const limit = 4294967296 - 4294967296 % bound;
do {
    window.crypto.getRandomValues(ta32);
} while (ta32[0] >= limit);
return ta32[0] % bound;

Mul shf bigint

if ((bound & -bound) === bound) {
    window.crypto.getRandomValues(ta32);
    return ta32[0] * bound / 4294967296 >>> 0;
}
const limit = (-bound >>> 0) % bound;
let bits, mLow;
  let mHigh;
  do {
    window.crypto.getRandomValues(ta32);
    bits = ta32[0] >>> 1;
    const m = BigInt(bits) * BigInt(bound);
    mLow  = Number(m & 2147483647n);
    mHigh = Number(m >> 31n);
  } while (mLow < limit);
return mHigh;

Mul shf 32

if ((bound & -bound) === bound) {
    window.crypto.getRandomValues(ta32);
    return ta32[0] * bound / 4294967296 >>> 0;
}
const limit = (-bound >>> 0) % bound;
let value;
do {
    window.crypto.getRandomValues(ta32);
    value = ta32[0] * bound;
} while ((value & 4294967295) % bound < limit);
return value / 4294967296 >>> 0;

java nextInt16(bound)

if ((bound & -bound) === bound) {
    crypto.getRandomValues(ta16);
    return bound * ta16[0] >>> 16;
}
let value;
do {
    crypto.getRandomValues(ta16);
    value = ta16[0] % bound;
} while (ta16[0] - value + (bound - 1) < 0);
return value;

java nextInt32(bound)

if ((bound & -bound) === bound) {
    window.crypto.getRandomValues(ta32);
    return ta32[0] * bound / 4294967296 >>> 0;
}
let bits, value;
do {
    window.crypto.getRandomValues(ta32);
    bits = ta32[0] >>> 1;
    value = bits % bound;
} while (bits - value + (bound - 1) < 0);
return value;