export function nextAfterF64()

in src/webgpu/util/math.ts [118:165]

• 38 lines of code
• 13 McCabe index (conditional complexity)

export function nextAfterF64(val: number, dir: NextDirection, mode: FlushMode): number {
  if (Number.isNaN(val)) {
    return val;
  }

  if (val === Number.POSITIVE_INFINITY) {
    return kValue.f64.positive.infinity;
  }

  if (val === Number.NEGATIVE_INFINITY) {
    return kValue.f64.negative.infinity;
  }

  assert(
    val <= kValue.f64.positive.max && val >= kValue.f64.negative.min,
    `${val} is not in the range of f64`
  );

  val = mode === 'flush' ? flushSubnormalNumberF64(val) : val;

  // -/+0 === 0 returns true
  if (val === 0) {
    if (dir === 'positive') {
      return mode === 'flush' ? kValue.f64.positive.min : kValue.f64.positive.subnormal.min;
    } else {
      return mode === 'flush' ? kValue.f64.negative.max : kValue.f64.negative.subnormal.max;
    }
  }

  nextAfterF64Float[0] = val;
  const is_positive = (nextAfterF64Int[0] & 0x8000_0000_0000_0000n) === 0n;
  if (is_positive === (dir === 'positive')) {
    nextAfterF64Int[0] += 1n;
  } else {
    nextAfterF64Int[0] -= 1n;
  }

  // Checking for overflow
  if ((nextAfterF64Int[0] & 0x7ff0_0000_0000_0000n) === 0x7ff0_0000_0000_0000n) {
    if (dir === 'positive') {
      return kValue.f64.positive.infinity;
    } else {
      return kValue.f64.negative.infinity;
    }
  }

  return mode === 'flush' ? flushSubnormalNumberF64(nextAfterF64Float[0]) : nextAfterF64Float[0];
}