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