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/* This file is distributed under the University of Illinois Open Source
* License. See LICENSE.TXT for details.
*/
/* long double __floatunditf(unsigned long long x); */
/* This file implements the PowerPC unsigned long long -> long double conversion */
#include "DD.h"
#include <stdint.h>
long double __floatunditf(uint64_t a) {
/* Begins with an exact copy of the code from __floatundidf */
static const double twop52 = 0x1.0p52;
static const double twop84 = 0x1.0p84;
static const double twop84_plus_twop52 = 0x1.00000001p84;
doublebits high = { .d = twop84 };
doublebits low = { .d = twop52 };
high.x |= a >> 32; /* 0x1.0p84 + high 32 bits of a */
low.x |= a & UINT64_C(0x00000000ffffffff); /* 0x1.0p52 + low 32 bits of a */
const double high_addend = high.d - twop84_plus_twop52;
/* At this point, we have two double precision numbers
* high_addend and low.d, and we wish to return their sum
* as a canonicalized long double:
*/
/* This implementation sets the inexact flag spuriously. */
/* This could be avoided, but at some substantial cost. */
DD result;
result.s.hi = high_addend + low.d;
result.s.lo = (high_addend - result.s.hi) + low.d;
return result.ld;
}
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