fixsfsi.c revision 2d1fdb26e458c4ddc04155c1d421bced3ba90cd0 
1//===-- lib/fixsfsi.c - Single-precision -> integer conversion ----*- C -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is dual licensed under the MIT and the University of Illinois Open
6// Source Licenses. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements single-precision to integer conversion for the
11// compiler-rt library.  No range checking is performed; the behavior of this
12// conversion is undefined for out of range values in the C standard.
13//
14//===----------------------------------------------------------------------===//
15
16#define SINGLE_PRECISION
17#include "fp_lib.h"
18
19ARM_EABI_FNALIAS(f2iz, fixsfsi)
20
21COMPILER_RT_ABI int
22__fixsfsi(fp_t a) {
23    // Break a into sign, exponent, significand
24    const rep_t aRep = toRep(a);
25    const rep_t aAbs = aRep & absMask;
26    const int sign = aRep & signBit ? -1 : 1;
27    const int exponent = (aAbs >> significandBits) - exponentBias;
28    const rep_t significand = (aAbs & significandMask) | implicitBit;
29
30    // If 0 < exponent < significandBits, right shift to get the result.
31    if ((unsigned int)exponent < significandBits) {
32        return sign * (significand >> (significandBits - exponent));
33    }
34
35    // If exponent is negative, the result is zero.
36    else if (exponent < 0) {
37        return 0;
38    }
39
40    // If significandBits < exponent, left shift to get the result.  This shift
41    // may end up being larger than the type width, which incurs undefined
42    // behavior, but the conversion itself is undefined in that case, so
43    // whatever the compiler decides to do is fine.
44    else {
45        return sign * (significand << (exponent - significandBits));
46    }
47}
48