github.com/igggame/nebulas-go@v2.1.0+incompatible/nbre/3rd_party/SoftFloat-3e/source/s_subMagsF32.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 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  float32_t softfloat_subMagsF32( uint_fast32_t uiA, uint_fast32_t uiB )
    45  {
    46      int_fast16_t expA;
    47      uint_fast32_t sigA;
    48      int_fast16_t expB;
    49      uint_fast32_t sigB;
    50      int_fast16_t expDiff;
    51      uint_fast32_t uiZ;
    52      int_fast32_t sigDiff;
    53      bool signZ;
    54      int_fast8_t shiftDist;
    55      int_fast16_t expZ;
    56      uint_fast32_t sigX, sigY;
    57      union ui32_f32 uZ;
    58  
    59      /*------------------------------------------------------------------------
    60      *------------------------------------------------------------------------*/
    61      expA = expF32UI( uiA );
    62      sigA = fracF32UI( uiA );
    63      expB = expF32UI( uiB );
    64      sigB = fracF32UI( uiB );
    65      /*------------------------------------------------------------------------
    66      *------------------------------------------------------------------------*/
    67      expDiff = expA - expB;
    68      if ( ! expDiff ) {
    69          /*--------------------------------------------------------------------
    70          *--------------------------------------------------------------------*/
    71          if ( expA == 0xFF ) {
    72              if ( sigA | sigB ) goto propagateNaN;
    73              softfloat_raiseFlags( softfloat_flag_invalid );
    74              uiZ = defaultNaNF32UI;
    75              goto uiZ;
    76          }
    77          sigDiff = sigA - sigB;
    78          if ( ! sigDiff ) {
    79              uiZ =
    80                  packToF32UI(
    81                      (softfloat_roundingMode == softfloat_round_min), 0, 0 );
    82              goto uiZ;
    83          }
    84          if ( expA ) --expA;
    85          signZ = signF32UI( uiA );
    86          if ( sigDiff < 0 ) {
    87              signZ = ! signZ;
    88              sigDiff = -sigDiff;
    89          }
    90          shiftDist = softfloat_countLeadingZeros32( sigDiff ) - 8;
    91          expZ = expA - shiftDist;
    92          if ( expZ < 0 ) {
    93              shiftDist = expA;
    94              expZ = 0;
    95          }
    96          uiZ = packToF32UI( signZ, expZ, sigDiff<<shiftDist );
    97          goto uiZ;
    98      } else {
    99          /*--------------------------------------------------------------------
   100          *--------------------------------------------------------------------*/
   101          signZ = signF32UI( uiA );
   102          sigA <<= 7;
   103          sigB <<= 7;
   104          if ( expDiff < 0 ) {
   105              /*----------------------------------------------------------------
   106              *----------------------------------------------------------------*/
   107              signZ = ! signZ;
   108              if ( expB == 0xFF ) {
   109                  if ( sigB ) goto propagateNaN;
   110                  uiZ = packToF32UI( signZ, 0xFF, 0 );
   111                  goto uiZ;
   112              }
   113              expZ = expB - 1;
   114              sigX = sigB | 0x40000000;
   115              sigY = sigA + (expA ? 0x40000000 : sigA);
   116              expDiff = -expDiff;
   117          } else {
   118              /*----------------------------------------------------------------
   119              *----------------------------------------------------------------*/
   120              if ( expA == 0xFF ) {
   121                  if ( sigA ) goto propagateNaN;
   122                  uiZ = uiA;
   123                  goto uiZ;
   124              }
   125              expZ = expA - 1;
   126              sigX = sigA | 0x40000000;
   127              sigY = sigB + (expB ? 0x40000000 : sigB);
   128          }
   129          return
   130              softfloat_normRoundPackToF32(
   131                  signZ, expZ, sigX - softfloat_shiftRightJam32( sigY, expDiff )
   132              );
   133      }
   134      /*------------------------------------------------------------------------
   135      *------------------------------------------------------------------------*/
   136   propagateNaN:
   137      uiZ = softfloat_propagateNaNF32UI( uiA, uiB );
   138   uiZ:
   139      uZ.ui = uiZ;
   140      return uZ.f;
   141  
   142  }
   143