StdLib/LibC/Main/Arm/floatunsidf.c

   1 /**
   2 University of Illinois/NCSA
   3 Open Source License
   4
   5 Copyright (c) 2009-2014 by the contributors listed in CREDITS.TXT
   6
   7 All rights reserved.
   8
   9 Developed by:
  10
  11     LLVM Team
  12
  13     University of Illinois at Urbana-Champaign
  14
  15     http://llvm.org
  16
  17 Permission is hereby granted, free of charge, to any person obtaining a copy of
  18 this software and associated documentation files (the "Software"), to deal with
  19 the Software without restriction, including without limitation the rights to
  20 use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
  21 of the Software, and to permit persons to whom the Software is furnished to do
  22 so, subject to the following conditions:
  23
  24     * Redistributions of source code must retain the above copyright notice,
  25       this list of conditions and the following disclaimers.
  26
  27     * Redistributions in binary form must reproduce the above copyright notice,
  28       this list of conditions and the following disclaimers in the
  29       documentation and/or other materials provided with the distribution.
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  31     * Neither the names of the LLVM Team, University of Illinois at
  32       Urbana-Champaign, nor the names of its contributors may be used to
  33       endorse or promote products derived from this Software without specific
  34       prior written permission.
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  36 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  37 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
  38 FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
  39 CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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  42 SOFTWARE.
  43 **/
  44
  45 #define DOUBLE_PRECISION
  46 #include "fp_lib.h"
  47
  48 #include "int_lib.h"
  49
  50 ARM_EABI_FNALIAS(ui2d, floatunsidf)
  51
  52 COMPILER_RT_ABI fp_t
  53 __floatunsidf(unsigned int a) {
  54
  55     const int aWidth = sizeof a * CHAR_BIT;
  56
  57     // Handle zero as a special case to protect clz
  58     if (a == 0) return fromRep(0);
  59
  60     // Exponent of (fp_t)a is the width of abs(a).
  61     const int exponent = (aWidth - 1) - __builtin_clz(a);
  62     rep_t result;
  63
  64     // Shift a into the significand field and clear the implicit bit.
  65     const int shift = significandBits - exponent;
  66     result = (rep_t)a << shift ^ implicitBit;
  67
  68     // Insert the exponent
  69     result += (rep_t)(exponent + exponentBias) << significandBits;
  70     return fromRep(result);
  71 }