xref: /freebsd-11.0-release/contrib/compiler-rt/lib/builtins/fp_fixuint_impl.inc

//===-- lib/fixdfsi.c - Double-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 float to unsigned integer conversion for the
// compiler-rt library.
//
//===----------------------------------------------------------------------===//

#include "fp_lib.h"

static inline fixuint_t __fixuint(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 either the value or the exponent is negative, the result is zero.
    if (sign == -1 || exponent < 0)
        return 0;

    // If the value is too large for the integer type, saturate.
    if ((unsigned)exponent > sizeof(fixuint_t) * CHAR_BIT)
        return ~(fixuint_t)0;

    // If 0 <= exponent < significandBits, right shift to get the result.
    // Otherwise, shift left.
    if (exponent < significandBits)
        return significand >> (significandBits - exponent);
    else
        return (fixuint_t)significand << (exponent - significandBits);
}