fixsfsi.c revision 37b97d1cf4501b94347e0b4e880f4b25825a289f 
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
19#include "int_lib.h"
20
21ARM_EABI_FNALIAS(f2iz, fixsfsi);
22
23int __fixsfsi(fp_t a) {
24
25    // Break a into sign, exponent, significand
26    const rep_t aRep = toRep(a);
27    const rep_t aAbs = aRep & absMask;
28    const int sign = aRep & signBit ? -1 : 1;
29    const int exponent = (aAbs >> significandBits) - exponentBias;
30    const rep_t significand = (aAbs & significandMask) | implicitBit;
31
32    // If 0 < exponent < significandBits, right shift to get the result.
33    if ((unsigned int)exponent < significandBits) {
34        return sign * (significand >> (significandBits - exponent));
35    }
36
37    // If exponent is negative, the result is zero.
38    else if (exponent < 0) {
39        return 0;
40    }
41
42    // If significandBits < exponent, left shift to get the result.  This shift
43    // may end up being larger than the type width, which incurs undefined
44    // behavior, but the conversion itself is undefined in that case, so
45    // whatever the compiler decides to do is fine.
46    else {
47        return sign * (significand << (exponent - significandBits));
48    }
49}
50