1 /* This file is distributed under the University of Illinois Open Source 2 * License. See LICENSE.TXT for details. 3 */ 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 31 /* This implementation sets the inexact flag spuriously. */ 32 /* This could be avoided, but at some substantial cost. */ 33 34 DD result; 35 36 result.s.hi = high_addend + low.d; 37 result.s.lo = (high_addend - result.s.hi) + low.d; 38 39 return result.ld; 40 41 } 42
