github.com/igggame/nebulas-go@v2.1.0+incompatible/nbre/3rd_party/SoftFloat-3e/source/f64_mul.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 The Regents of the University of California.
     8  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  float64_t f64_mul( float64_t a, float64_t b )
    45  {
    46      union ui64_f64 uA;
    47      uint_fast64_t uiA;
    48      bool signA;
    49      int_fast16_t expA;
    50      uint_fast64_t sigA;
    51      union ui64_f64 uB;
    52      uint_fast64_t uiB;
    53      bool signB;
    54      int_fast16_t expB;
    55      uint_fast64_t sigB;
    56      bool signZ;
    57      uint_fast64_t magBits;
    58      struct exp16_sig64 normExpSig;
    59      int_fast16_t expZ;
    60  #ifdef SOFTFLOAT_FAST_INT64
    61      struct uint128 sig128Z;
    62  #else
    63      uint32_t sig128Z[4];
    64  #endif
    65      uint_fast64_t sigZ, uiZ;
    66      union ui64_f64 uZ;
    67  
    68      /*------------------------------------------------------------------------
    69      *------------------------------------------------------------------------*/
    70      uA.f = a;
    71      uiA = uA.ui;
    72      signA = signF64UI( uiA );
    73      expA  = expF64UI( uiA );
    74      sigA  = fracF64UI( uiA );
    75      uB.f = b;
    76      uiB = uB.ui;
    77      signB = signF64UI( uiB );
    78      expB  = expF64UI( uiB );
    79      sigB  = fracF64UI( uiB );
    80      signZ = signA ^ signB;
    81      /*------------------------------------------------------------------------
    82      *------------------------------------------------------------------------*/
    83      if ( expA == 0x7FF ) {
    84          if ( sigA || ((expB == 0x7FF) && sigB) ) goto propagateNaN;
    85          magBits = expB | sigB;
    86          goto infArg;
    87      }
    88      if ( expB == 0x7FF ) {
    89          if ( sigB ) goto propagateNaN;
    90          magBits = expA | sigA;
    91          goto infArg;
    92      }
    93      /*------------------------------------------------------------------------
    94      *------------------------------------------------------------------------*/
    95      if ( ! expA ) {
    96          if ( ! sigA ) goto zero;
    97          normExpSig = softfloat_normSubnormalF64Sig( sigA );
    98          expA = normExpSig.exp;
    99          sigA = normExpSig.sig;
   100      }
   101      if ( ! expB ) {
   102          if ( ! sigB ) goto zero;
   103          normExpSig = softfloat_normSubnormalF64Sig( sigB );
   104          expB = normExpSig.exp;
   105          sigB = normExpSig.sig;
   106      }
   107      /*------------------------------------------------------------------------
   108      *------------------------------------------------------------------------*/
   109      expZ = expA + expB - 0x3FF;
   110      sigA = (sigA | UINT64_C( 0x0010000000000000 ))<<10;
   111      sigB = (sigB | UINT64_C( 0x0010000000000000 ))<<11;
   112  #ifdef SOFTFLOAT_FAST_INT64
   113      sig128Z = softfloat_mul64To128( sigA, sigB );
   114      sigZ = sig128Z.v64 | (sig128Z.v0 != 0);
   115  #else
   116      softfloat_mul64To128M( sigA, sigB, sig128Z );
   117      sigZ =
   118          (uint64_t) sig128Z[indexWord( 4, 3 )]<<32 | sig128Z[indexWord( 4, 2 )];
   119      if ( sig128Z[indexWord( 4, 1 )] || sig128Z[indexWord( 4, 0 )] ) sigZ |= 1;
   120  #endif
   121      if ( sigZ < UINT64_C( 0x4000000000000000 ) ) {
   122          --expZ;
   123          sigZ <<= 1;
   124      }
   125      return softfloat_roundPackToF64( signZ, expZ, sigZ );
   126      /*------------------------------------------------------------------------
   127      *------------------------------------------------------------------------*/
   128   propagateNaN:
   129      uiZ = softfloat_propagateNaNF64UI( uiA, uiB );
   130      goto uiZ;
   131      /*------------------------------------------------------------------------
   132      *------------------------------------------------------------------------*/
   133   infArg:
   134      if ( ! magBits ) {
   135          softfloat_raiseFlags( softfloat_flag_invalid );
   136          uiZ = defaultNaNF64UI;
   137      } else {
   138          uiZ = packToF64UI( signZ, 0x7FF, 0 );
   139      }
   140      goto uiZ;
   141      /*------------------------------------------------------------------------
   142      *------------------------------------------------------------------------*/
   143   zero:
   144      uiZ = packToF64UI( signZ, 0, 0 );
   145   uiZ:
   146      uZ.ui = uiZ;
   147      return uZ.f;
   148  
   149  }
   150