github.com/igggame/nebulas-go@v2.1.0+incompatible/nbre/3rd_party/SoftFloat-3e/source/s_subMagsF128.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  float128_t
    45   softfloat_subMagsF128(
    46       uint_fast64_t uiA64,
    47       uint_fast64_t uiA0,
    48       uint_fast64_t uiB64,
    49       uint_fast64_t uiB0,
    50       bool signZ
    51   )
    52  {
    53      int_fast32_t expA;
    54      struct uint128 sigA;
    55      int_fast32_t expB;
    56      struct uint128 sigB, sigZ;
    57      int_fast32_t expDiff, expZ;
    58      struct uint128 uiZ;
    59      union ui128_f128 uZ;
    60  
    61      expA = expF128UI64( uiA64 );
    62      sigA.v64 = fracF128UI64( uiA64 );
    63      sigA.v0  = uiA0;
    64      expB = expF128UI64( uiB64 );
    65      sigB.v64 = fracF128UI64( uiB64 );
    66      sigB.v0  = uiB0;
    67      sigA = softfloat_shortShiftLeft128( sigA.v64, sigA.v0, 4 );
    68      sigB = softfloat_shortShiftLeft128( sigB.v64, sigB.v0, 4 );
    69      expDiff = expA - expB;
    70      if ( 0 < expDiff ) goto expABigger;
    71      if ( expDiff < 0 ) goto expBBigger;
    72      if ( expA == 0x7FFF ) {
    73          if ( sigA.v64 | sigA.v0 | sigB.v64 | sigB.v0 ) goto propagateNaN;
    74          softfloat_raiseFlags( softfloat_flag_invalid );
    75          uiZ.v64 = defaultNaNF128UI64;
    76          uiZ.v0  = defaultNaNF128UI0;
    77          goto uiZ;
    78      }
    79      expZ = expA;
    80      if ( ! expZ ) expZ = 1;
    81      if ( sigB.v64 < sigA.v64 ) goto aBigger;
    82      if ( sigA.v64 < sigB.v64 ) goto bBigger;
    83      if ( sigB.v0 < sigA.v0 ) goto aBigger;
    84      if ( sigA.v0 < sigB.v0 ) goto bBigger;
    85      uiZ.v64 =
    86          packToF128UI64(
    87              (softfloat_roundingMode == softfloat_round_min), 0, 0 );
    88      uiZ.v0 = 0;
    89      goto uiZ;
    90   expBBigger:
    91      if ( expB == 0x7FFF ) {
    92          if ( sigB.v64 | sigB.v0 ) goto propagateNaN;
    93          uiZ.v64 = packToF128UI64( signZ ^ 1, 0x7FFF, 0 );
    94          uiZ.v0  = 0;
    95          goto uiZ;
    96      }
    97      if ( expA ) {
    98          sigA.v64 |= UINT64_C( 0x0010000000000000 );
    99      } else {
   100          ++expDiff;
   101          if ( ! expDiff ) goto newlyAlignedBBigger;
   102      }
   103      sigA = softfloat_shiftRightJam128( sigA.v64, sigA.v0, -expDiff );
   104   newlyAlignedBBigger:
   105      expZ = expB;
   106      sigB.v64 |= UINT64_C( 0x0010000000000000 );
   107   bBigger:
   108      signZ = ! signZ;
   109      sigZ = softfloat_sub128( sigB.v64, sigB.v0, sigA.v64, sigA.v0 );
   110      goto normRoundPack;
   111   expABigger:
   112      if ( expA == 0x7FFF ) {
   113          if ( sigA.v64 | sigA.v0 ) goto propagateNaN;
   114          uiZ.v64 = uiA64;
   115          uiZ.v0  = uiA0;
   116          goto uiZ;
   117      }
   118      if ( expB ) {
   119          sigB.v64 |= UINT64_C( 0x0010000000000000 );
   120      } else {
   121          --expDiff;
   122          if ( ! expDiff ) goto newlyAlignedABigger;
   123      }
   124      sigB = softfloat_shiftRightJam128( sigB.v64, sigB.v0, expDiff );
   125   newlyAlignedABigger:
   126      expZ = expA;
   127      sigA.v64 |= UINT64_C( 0x0010000000000000 );
   128   aBigger:
   129      sigZ = softfloat_sub128( sigA.v64, sigA.v0, sigB.v64, sigB.v0 );
   130   normRoundPack:
   131      return softfloat_normRoundPackToF128( signZ, expZ - 5, sigZ.v64, sigZ.v0 );
   132   propagateNaN:
   133      uiZ = softfloat_propagateNaNF128UI( uiA64, uiA0, uiB64, uiB0 );
   134   uiZ:
   135      uZ.ui = uiZ;
   136      return uZ.f;
   137  
   138  }
   139