llvm-project/compiler-rt/lib/fixsfsi.c

46 lines
1.7 KiB
C

//===-- lib/fixsfsi.c - Single-precision -> integer conversion ----*- C -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements single-precision to integer conversion for the
// compiler-rt library. No range checking is performed; the behavior of this
// conversion is undefined for out of range values in the C standard.
//
//===----------------------------------------------------------------------===//
#define SINGLE_PRECISION
#include "fp_lib.h"
int __fixsfsi(fp_t a) {
// Break a into sign, exponent, significand
const rep_t aRep = toRep(a);
const rep_t aAbs = aRep & absMask;
const int sign = aRep & signBit ? -1 : 1;
const int exponent = (aAbs >> significandBits) - exponentBias;
const rep_t significand = (aAbs & significandMask) | implicitBit;
// If 0 < exponent < significandBits, right shift to get the result.
if ((unsigned int)exponent < significandBits) {
return sign * (significand >> (significandBits - exponent));
}
// If exponent is negative, the result is zero.
else if (exponent < 0) {
return 0;
}
// If significandBits < exponent, left shift to get the result. This shift
// may end up being larger than the type width, which incurs undefined
// behavior, but the conversion itself is undefined in that case, so
// whatever the compiler decides to do is fine.
else {
return sign * (significand << (exponent - significandBits));
}
}