| 1 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 2 | // See https://llvm.org/LICENSE.txt for license information. |
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| 3 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 4 | |
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| 5 | // long double __floatunditf(unsigned long long x); |
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| 6 | // This file implements the PowerPC unsigned long long -> long double conversion |
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| 7 | |
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| 8 | #include "DD.h" |
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| 9 | |
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| 10 | long double __floatunditf(uint64_t a) { |
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| 11 | |
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| 12 | // Begins with an exact copy of the code from __floatundidf |
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| 13 | |
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| 14 | static const double twop52 = 0x1.0p52; |
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| 15 | static const double twop84 = 0x1.0p84; |
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| 16 | static const double twop84_plus_twop52 = 0x1.00000001p84; |
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| 17 | |
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| 18 | doublebits high = {.d = twop84}; |
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| 19 | doublebits low = {.d = twop52}; |
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| 20 | |
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| 21 | high.x |= a >> 32; // 0x1.0p84 + high 32 bits of a |
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| 22 | low.x |= a & UINT64_C(0x00000000ffffffff); // 0x1.0p52 + low 32 bits of a |
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| 23 | |
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| 24 | const double high_addend = high.d - twop84_plus_twop52; |
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| 25 | |
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| 26 | // At this point, we have two double precision numbers |
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| 27 | // high_addend and low.d, and we wish to return their sum |
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| 28 | // as a canonicalized long double: |
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| 29 | |
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| 30 | // This implementation sets the inexact flag spuriously. |
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| 31 | // This could be avoided, but at some substantial cost. |
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| 32 | |
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| 33 | DD result; |
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| 34 | |
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| 35 | result.s.hi = high_addend + low.d; |
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| 36 | result.s.lo = (high_addend - result.s.hi) + low.d; |
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| 37 | |
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| 38 | return result.ld; |
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| 39 | } |
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| 40 | |
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