1// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
2// See https://llvm.org/LICENSE.txt for license information.
3// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
4
5// long double __gcc_qdiv(long double x, long double y);
6// This file implements the PowerPC 128-bit double-double division operation.
7// This implementation is shamelessly cribbed from Apple's DDRT, circa 1993(!)
8
9#include "DD.h"
10
11long double __gcc_qdiv(long double a, long double b) {
12  static const uint32_t infinityHi = UINT32_C(0x7ff00000);
13  DD dst = {.ld = a}, src = {.ld = b};
14
15  register double x = dst.s.hi, x1 = dst.s.lo, y = src.s.hi, y1 = src.s.lo;
16
17  double yHi, yLo, qHi, qLo;
18  double yq, tmp, q;
19
20  q = x / y;
21
22  // Detect special cases
23  if (q == 0.0) {
24    dst.s.hi = q;
25    dst.s.lo = 0.0;
26    return dst.ld;
27  }
28
29  const doublebits qBits = {.d = q};
30  if (((uint32_t)(qBits.x >> 32) & infinityHi) == infinityHi) {
31    dst.s.hi = q;
32    dst.s.lo = 0.0;
33    return dst.ld;
34  }
35
36  yHi = high26bits(y);
37  qHi = high26bits(q);
38
39  yq = y * q;
40  yLo = y - yHi;
41  qLo = q - qHi;
42
43  tmp = LOWORDER(yq, yHi, yLo, qHi, qLo);
44  tmp = (x - yq) - tmp;
45  tmp = ((tmp + x1) - y1 * q) / y;
46  x = q + tmp;
47
48  dst.s.lo = (q - x) + tmp;
49  dst.s.hi = x;
50
51  return dst.ld;
52}
53