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
5 // long double __gcc_qmul(long double x, long double y);
6 // This file implements the PowerPC 128-bit double-double multiply operation.
7 // This implementation is shamelessly cribbed from Apple's DDRT, circa 1993(!)
11 long double __gcc_qmul(long double x, long double y) {
12 static const uint32_t infinityHi = UINT32_C(0x7ff00000);
13 DD dst = {.ld = x}, src = {.ld = y};
15 register double A = dst.s.hi, a = dst.s.lo, B = src.s.hi, b = src.s.lo;
17 double aHi, aLo, bHi, bLo;
22 // Detect special cases
29 const doublebits abBits = {.d = ab};
30 if (((uint32_t)(abBits.x >> 32) & infinityHi) == infinityHi) {
36 // Generic cases handled here.
42 tmp = LOWORDER(ab, aHi, aLo, bHi, bLo);
43 tmp += (A * b + a * B);
46 dst.s.lo = (ab - tau) + tmp;