// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // long double __gcc_qmul(long double x, long double y); // This file implements the PowerPC 128-bit double-double multiply operation. // This implementation is shamelessly cribbed from Apple's DDRT, circa 1993(!) #include "DD.h" long double __gcc_qmul(long double x, long double y) { static const uint32_t infinityHi = UINT32_C(0x7ff00000); DD dst = {.ld = x}, src = {.ld = y}; register double A = dst.s.hi, a = dst.s.lo, B = src.s.hi, b = src.s.lo; double aHi, aLo, bHi, bLo; double ab, tmp, tau; ab = A * B; // Detect special cases if (ab == 0.0) { dst.s.hi = ab; dst.s.lo = 0.0; return dst.ld; } const doublebits abBits = {.d = ab}; if (((uint32_t)(abBits.x >> 32) & infinityHi) == infinityHi) { dst.s.hi = ab; dst.s.lo = 0.0; return dst.ld; } // Generic cases handled here. aHi = high26bits(A); bHi = high26bits(B); aLo = A - aHi; bLo = B - bHi; tmp = LOWORDER(ab, aHi, aLo, bHi, bLo); tmp += (A * b + a * B); tau = ab + tmp; dst.s.lo = (ab - tau) + tmp; dst.s.hi = tau; return dst.ld; } |