github.com/igggame/nebulas-go@v2.1.0+incompatible/nbre/3rd_party/SoftFloat-3e/source/f128M_to_f64.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 The Regents of the University of
     8  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  #ifdef SOFTFLOAT_FAST_INT64
    45  
    46  float64_t f128M_to_f64( const float128_t *aPtr )
    47  {
    48  
    49      return f128_to_f64( *aPtr );
    50  
    51  }
    52  
    53  #else
    54  
    55  float64_t f128M_to_f64( const float128_t *aPtr )
    56  {
    57      const uint32_t *aWPtr;
    58      uint32_t uiA96;
    59      bool sign;
    60      int32_t exp;
    61      uint64_t frac64;
    62      struct commonNaN commonNaN;
    63      uint64_t uiZ;
    64      uint32_t frac32;
    65      union ui64_f64 uZ;
    66  
    67      /*------------------------------------------------------------------------
    68      *------------------------------------------------------------------------*/
    69      aWPtr = (const uint32_t *) aPtr;
    70      uiA96 = aWPtr[indexWordHi( 4 )];
    71      sign = signF128UI96( uiA96 );
    72      exp  = expF128UI96( uiA96 );
    73      frac64 = (uint64_t) fracF128UI96( uiA96 )<<32 | aWPtr[indexWord( 4, 2 )];
    74      /*------------------------------------------------------------------------
    75      *------------------------------------------------------------------------*/
    76      if ( exp == 0x7FFF ) {
    77          if ( frac64 || aWPtr[indexWord( 4, 1 )] | aWPtr[indexWord( 4, 0 )] ) {
    78              softfloat_f128MToCommonNaN( aWPtr, &commonNaN );
    79              uiZ = softfloat_commonNaNToF64UI( &commonNaN );
    80          } else {
    81              uiZ = packToF64UI( sign, 0x7FF, 0 );
    82          }
    83          goto uiZ;
    84      }
    85      /*------------------------------------------------------------------------
    86      *------------------------------------------------------------------------*/
    87      frac32 = aWPtr[indexWord( 4, 1 )];
    88      frac64 = frac64<<14 | frac32>>18;
    89      if ( (frac32 & 0x0003FFFF) || aWPtr[indexWord( 4, 0 )] ) frac64 |= 1;
    90      if ( ! (exp | frac64) ) {
    91          uiZ = packToF64UI( sign, 0, 0 );
    92          goto uiZ;
    93      }
    94      /*------------------------------------------------------------------------
    95      *------------------------------------------------------------------------*/
    96      exp -= 0x3C01;
    97      if ( sizeof (int_fast16_t) < sizeof (int32_t) ) {
    98          if ( exp < -0x1000 ) exp = -0x1000;
    99      }
   100      return
   101          softfloat_roundPackToF64(
   102              sign, exp, frac64 | UINT64_C( 0x4000000000000000 ) );
   103      /*------------------------------------------------------------------------
   104      *------------------------------------------------------------------------*/
   105   uiZ:
   106      uZ.ui = uiZ;
   107      return uZ.f;
   108  
   109  }
   110  
   111  #endif
   112