1*156cd587Sjoerg /* This file is distributed under the University of Illinois Open Source 2*156cd587Sjoerg * License. See LICENSE.TXT for details. 3*156cd587Sjoerg */ 4*156cd587Sjoerg 5*156cd587Sjoerg /* long double __floatunditf(unsigned long long x); */ 6*156cd587Sjoerg /* This file implements the PowerPC unsigned long long -> long double conversion */ 7*156cd587Sjoerg 8*156cd587Sjoerg #include "DD.h" 9*156cd587Sjoerg __floatunditf(uint64_t a)10*156cd587Sjoerglong double __floatunditf(uint64_t a) { 11*156cd587Sjoerg 12*156cd587Sjoerg /* Begins with an exact copy of the code from __floatundidf */ 13*156cd587Sjoerg 14*156cd587Sjoerg static const double twop52 = 0x1.0p52; 15*156cd587Sjoerg static const double twop84 = 0x1.0p84; 16*156cd587Sjoerg static const double twop84_plus_twop52 = 0x1.00000001p84; 17*156cd587Sjoerg 18*156cd587Sjoerg doublebits high = { .d = twop84 }; 19*156cd587Sjoerg doublebits low = { .d = twop52 }; 20*156cd587Sjoerg 21*156cd587Sjoerg high.x |= a >> 32; /* 0x1.0p84 + high 32 bits of a */ 22*156cd587Sjoerg low.x |= a & UINT64_C(0x00000000ffffffff); /* 0x1.0p52 + low 32 bits of a */ 23*156cd587Sjoerg 24*156cd587Sjoerg const double high_addend = high.d - twop84_plus_twop52; 25*156cd587Sjoerg 26*156cd587Sjoerg /* At this point, we have two double precision numbers 27*156cd587Sjoerg * high_addend and low.d, and we wish to return their sum 28*156cd587Sjoerg * as a canonicalized long double: 29*156cd587Sjoerg */ 30*156cd587Sjoerg 31*156cd587Sjoerg /* This implementation sets the inexact flag spuriously. */ 32*156cd587Sjoerg /* This could be avoided, but at some substantial cost. */ 33*156cd587Sjoerg 34*156cd587Sjoerg DD result; 35*156cd587Sjoerg 36*156cd587Sjoerg result.s.hi = high_addend + low.d; 37*156cd587Sjoerg result.s.lo = (high_addend - result.s.hi) + low.d; 38*156cd587Sjoerg 39*156cd587Sjoerg return result.ld; 40*156cd587Sjoerg 41*156cd587Sjoerg } 42