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