src/libcompiler_builtins/compiler-rt/lib/builtins/fp_fixuint_impl.inc

   1 //===-- lib/fixdfsi.c - Double-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 float to unsigned integer conversion for the
  11 // compiler-rt library.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "fp_lib.h"
  16
  17 static __inline fixuint_t __fixuint(fp_t a) {
  18     // Break a into sign, exponent, significand
  19     const rep_t aRep = toRep(a);
  20     const rep_t aAbs = aRep & absMask;
  21     const int sign = aRep & signBit ? -1 : 1;
  22     const int exponent = (aAbs >> significandBits) - exponentBias;
  23     const rep_t significand = (aAbs & significandMask) | implicitBit;
  24
  25     // If either the value or the exponent is negative, the result is zero.
  26     if (sign == -1 || exponent < 0)
  27         return 0;
  28
  29     // If the value is too large for the integer type, saturate.
  30     if ((unsigned)exponent >= sizeof(fixuint_t) * CHAR_BIT)
  31         return ~(fixuint_t)0;
  32
  33     // If 0 <= exponent < significandBits, right shift to get the result.
  34     // Otherwise, shift left.
  35     if (exponent < significandBits)
  36         return significand >> (significandBits - exponent);
  37     else
  38         return (fixuint_t)significand << (exponent - significandBits);
  39 }