jsHelper64.js

jsHelper64.js

const uint64 = new BigUint64Array(1);
const uint32 = new Uint32Array(uint64.buffer);
function clz64(bigint) {
  uint64[0] = bigint;
  let x = Math.clz32(uint32[1]);
  let y = Math.clz32(uint32[0]);
  return x + (x === 32 ? y : 0);
}

function jsHelper64($x, $xlo, $y, $ylo) {
  let x = BigInt.asUintN(64, $x);
  let xlo = BigInt.asUintN(64, $xlo);
  let y = BigInt.asUintN(64, $y);
  let ylo = BigInt.asUintN(64, $ylo);
  let A = BigInt.asIntN(64, 1n);
  let B = BigInt.asIntN(64, 0n);
  let C = BigInt.asIntN(64, 0n);
  let D = BigInt.asIntN(64, 1n);
  let i = 7;
  let q = BigInt.asUintN(64, 1n);
  let y1 = BigInt.asUintN(64, 1n);
  let A1 = BigInt.asIntN(64, 1n);
  let B1 = BigInt.asIntN(64, 0n);
  let C1 = BigInt.asIntN(64, 0n);
  let D1 = BigInt.asIntN(64, 1n);
  let sameQuotient = 0;
  let bits = BigInt.asUintN(64, 0n);
  let xlo1 = BigInt.asIntN(64, 0n);
  let ylo1 = BigInt.asIntN(64, 0n);
  let lobits = BigInt.asUintN(64, 64n);
  const zero = BigInt.asIntN(64, 0n);
  do {
    A1 = A;
    B1 = B;
    C1 = C;
    D1 = D;
    y1 = y;
    y = x;
    do {
      x = y;
      y = y1;
      A = A1;
      B = B1;
      C = C1;
      D = D1;
      q = BigInt.asUintN(64, x / y);
      y1 = BigInt.asUintN(64, x - BigInt.asUintN(64, q * y));
      A1 = C;
      B1 = D;
      C1 = BigInt.asIntN(64, A - BigInt.asIntN(64, q * C));
      D1 = BigInt.asIntN(64, B - BigInt.asIntN(64, q * D));
      sameQuotient = (clz64(BigInt.asIntN(64, -D)) + clz64(D) + clz64(q) > 64) &
                     (
                       C1 < zero & BigInt.asUintN(64, -C1) < y1 & BigInt.asUintN(64, D1 - D) <= BigInt.asUintN(64, y - y1)
                       |
                       D1 < zero & BigInt.asUintN(64, -D1) < y1 & BigInt.asUintN(64, C1 - C) <= BigInt.asUintN(64, y - y1)
                     )
    } while (sameQuotient !== 0);
    bits = x < 0n ? 0n : BigInt(clz64(BigInt.asUintN(64, x + (B < A ? A : B))));
    if (bits !== 0n) {
      bits = lobits < bits ? lobits : bits;
      lobits = BigInt.asUintN(64, lobits - bits);
      xlo1 = BigInt.asUintN(64, xlo >> lobits);
      ylo1 = BigInt.asUintN(64, ylo >> lobits);
      xlo = BigInt.asUintN(64, xlo - BigInt.asUintN(64, xlo1 << lobits));
      ylo = BigInt.asUintN(64, ylo - BigInt.asUintN(64, ylo1 << lobits));
      x = BigInt.asUintN(64, BigInt.asUintN(64, BigInt.asUintN(64, A * xlo1) + BigInt.asUintN(64, B * ylo1)) + BigInt.asUintN(64, x << bits));
      y = BigInt.asUintN(64, BigInt.asUintN(64, BigInt.asUintN(64, C * xlo1) + BigInt.asUintN(64, D * ylo1)) + BigInt.asUintN(64, y << bits));
      i -= 1;
    }
  } while (i !== 0 && bits !== 0n);
  return [A, B, C, D];
}