compiler-rt/lib/fixunsxfdi.c

//===-- fixunsxfdi.c - Implement __fixunsxfdi -----------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements __fixunsxfdi for the compiler_rt library.
//
//===----------------------------------------------------------------------===//

#if !_ARCH_PPC

#include "int_lib.h"

// Returns: convert a to a unsigned long long, rounding toward zero.
//          Negative values all become zero.

// Assumption: long double is an intel 80 bit floating point type padded with 6 bytes
//             du_int is a 64 bit integral type
//             value in long double is representable in du_int or is negative 
//                 (no range checking performed)

// gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee eeee |
// 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm

du_int
__fixunsxfdi(long double a)
{
    long_double_bits fb;
    fb.f = a;
    int e = (fb.u.high.low & 0x00007FFF) - 16383;
    if (e < 0 || (fb.u.high.low & 0x00008000))
        return 0;
    return fb.u.low.all >> (63 - e);
}

#endif