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 __floatunditf(unsigned long long x); 6 // This file implements the PowerPC unsigned long long -> long double conversion 7 8 #include "DD.h" 9 10 long double __floatunditf(uint64_t a) { 11 12 // Begins with an exact copy of the code from __floatundidf 13 14 static const double twop52 = 0x1.0p52; 15 static const double twop84 = 0x1.0p84; 16 static const double twop84_plus_twop52 = 0x1.00000001p84; 17 18 doublebits high = {.d = twop84}; 19 doublebits low = {.d = twop52}; 20 21 high.x |= a >> 32; // 0x1.0p84 + high 32 bits of a 22 low.x |= a & UINT64_C(0x00000000ffffffff); // 0x1.0p52 + low 32 bits of a 23 24 const double high_addend = high.d - twop84_plus_twop52; 25 26 // At this point, we have two double precision numbers 27 // high_addend and low.d, and we wish to return their sum 28 // as a canonicalized long double: 29 30 // This implementation sets the inexact flag spuriously. 31 // This could be avoided, but at some substantial cost. 32 33 DD result; 34 35 result.s.hi = high_addend + low.d; 36 result.s.lo = (high_addend - result.s.hi) + low.d; 37 38 return result.ld; 39 } 40