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
__gcc_qdiv(long double a,long double b)11 long 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