github.com/igggame/nebulas-go@v2.1.0+incompatible/nbre/3rd_party/SoftFloat-3e/source/f16_to_ui64.c (about)

     1  
     2  /*============================================================================
     3  
     4  This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
     5  Package, Release 3e, by John R. Hauser.
     6  
     7  Copyright 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018 The Regents of the
     8  University of California.  All rights reserved.
     9  
    10  Redistribution and use in source and binary forms, with or without
    11  modification, are permitted provided that the following conditions are met:
    12  
    13   1. Redistributions of source code must retain the above copyright notice,
    14      this list of conditions, and the following disclaimer.
    15  
    16   2. Redistributions in binary form must reproduce the above copyright notice,
    17      this list of conditions, and the following disclaimer in the documentation
    18      and/or other materials provided with the distribution.
    19  
    20   3. Neither the name of the University nor the names of its contributors may
    21      be used to endorse or promote products derived from this software without
    22      specific prior written permission.
    23  
    24  THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY
    25  EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
    26  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE
    27  DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
    28  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
    29  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
    30  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
    31  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    32  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
    33  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    34  
    35  =============================================================================*/
    36  
    37  #include <stdbool.h>
    38  #include <stdint.h>
    39  #include "platform.h"
    40  #include "internals.h"
    41  #include "specialize.h"
    42  #include "softfloat.h"
    43  
    44  uint_fast64_t f16_to_ui64( float16_t a, uint_fast8_t roundingMode, bool exact )
    45  {
    46      union ui16_f16 uA;
    47      uint_fast16_t uiA;
    48      bool sign;
    49      int_fast8_t exp;
    50      uint_fast16_t frac;
    51      uint_fast32_t sig32;
    52      int_fast8_t shiftDist;
    53  #ifndef SOFTFLOAT_FAST_INT64
    54      uint32_t extSig[3];
    55  #endif
    56  
    57      /*------------------------------------------------------------------------
    58      *------------------------------------------------------------------------*/
    59      uA.f = a;
    60      uiA = uA.ui;
    61      sign = signF16UI( uiA );
    62      exp  = expF16UI( uiA );
    63      frac = fracF16UI( uiA );
    64      /*------------------------------------------------------------------------
    65      *------------------------------------------------------------------------*/
    66      if ( exp == 0x1F ) {
    67          softfloat_raiseFlags( softfloat_flag_invalid );
    68          return
    69              frac ? ui64_fromNaN
    70                  : sign ? ui64_fromNegOverflow : ui64_fromPosOverflow;
    71      }
    72      /*------------------------------------------------------------------------
    73      *------------------------------------------------------------------------*/
    74      sig32 = frac;
    75      if ( exp ) {
    76          sig32 |= 0x0400;
    77          shiftDist = exp - 0x19;
    78          if ( (0 <= shiftDist) && ! sign ) {
    79              return sig32<<shiftDist;
    80          }
    81          shiftDist = exp - 0x0D;
    82          if ( 0 < shiftDist ) sig32 <<= shiftDist;
    83      }
    84  #ifdef SOFTFLOAT_FAST_INT64
    85      return
    86          softfloat_roundToUI64(
    87              sign, sig32>>12, (uint_fast64_t) sig32<<52, roundingMode, exact );
    88  #else
    89      extSig[indexWord( 3, 2 )] = 0;
    90      extSig[indexWord( 3, 1 )] = sig32>>12;
    91      extSig[indexWord( 3, 0 )] = sig32<<20;
    92      return softfloat_roundMToUI64( sign, extSig, roundingMode, exact );
    93  #endif
    94  
    95  }
    96