1353358Sdim// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 2353358Sdim// See https://llvm.org/LICENSE.txt for license information. 3353358Sdim// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 4276789Sdim 5353358Sdim// long double __gcc_qmul(long double x, long double y); 6353358Sdim// This file implements the PowerPC 128-bit double-double multiply operation. 7353358Sdim// This implementation is shamelessly cribbed from Apple's DDRT, circa 1993(!) 8276789Sdim 9276789Sdim#include "DD.h" 10276789Sdim 11353358Sdimlong double __gcc_qmul(long double x, long double y) { 12353358Sdim static const uint32_t infinityHi = UINT32_C(0x7ff00000); 13353358Sdim DD dst = {.ld = x}, src = {.ld = y}; 14353358Sdim 15353358Sdim register double A = dst.s.hi, a = dst.s.lo, B = src.s.hi, b = src.s.lo; 16353358Sdim 17353358Sdim double aHi, aLo, bHi, bLo; 18353358Sdim double ab, tmp, tau; 19353358Sdim 20353358Sdim ab = A * B; 21353358Sdim 22353358Sdim // Detect special cases 23353358Sdim if (ab == 0.0) { 24353358Sdim dst.s.hi = ab; 25353358Sdim dst.s.lo = 0.0; 26276789Sdim return dst.ld; 27353358Sdim } 28353358Sdim 29353358Sdim const doublebits abBits = {.d = ab}; 30353358Sdim if (((uint32_t)(abBits.x >> 32) & infinityHi) == infinityHi) { 31353358Sdim dst.s.hi = ab; 32353358Sdim dst.s.lo = 0.0; 33353358Sdim return dst.ld; 34353358Sdim } 35353358Sdim 36353358Sdim // Generic cases handled here. 37353358Sdim aHi = high26bits(A); 38353358Sdim bHi = high26bits(B); 39353358Sdim aLo = A - aHi; 40353358Sdim bLo = B - bHi; 41353358Sdim 42353358Sdim tmp = LOWORDER(ab, aHi, aLo, bHi, bLo); 43353358Sdim tmp += (A * b + a * B); 44353358Sdim tau = ab + tmp; 45353358Sdim 46353358Sdim dst.s.lo = (ab - tau) + tmp; 47353358Sdim dst.s.hi = tau; 48353358Sdim 49353358Sdim return dst.ld; 50276789Sdim} 51