forked from OSchip/llvm-project
46 lines
1.7 KiB
C
46 lines
1.7 KiB
C
//===-- lib/fixdfsi.c - Double-precision -> integer conversion ----*- C -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// 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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//===----------------------------------------------------------------------===//
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//
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// This file implements double-precision to integer conversion for the
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// compiler-rt library. No range checking is performed; the behavior of this
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// conversion is undefined for out of range values in the C standard.
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//
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//===----------------------------------------------------------------------===//
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#define DOUBLE_PRECISION
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#include "fp_lib.h"
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int __fixdfsi(fp_t a) {
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// Break a into sign, exponent, significand
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const rep_t aRep = toRep(a);
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const rep_t aAbs = aRep & absMask;
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const int sign = aRep & signBit ? -1 : 1;
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const int exponent = (aAbs >> significandBits) - exponentBias;
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const rep_t significand = (aAbs & significandMask) | implicitBit;
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// If 0 < exponent < significandBits, right shift to get the result.
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if ((unsigned int)exponent < significandBits) {
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return sign * (significand >> (significandBits - exponent));
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}
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// If exponent is negative, the result is zero.
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else if (exponent < 0) {
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return 0;
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}
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// If significandBits < exponent, left shift to get the result. This shift
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// may end up being larger than the type width, which incurs undefined
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// behavior, but the conversion itself is undefined in that case, so
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// whatever the compiler decides to do is fine.
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else {
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return sign * (significand << (exponent - significandBits));
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}
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}
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