github.com/igggame/nebulas-go@v2.1.0+incompatible/nbre/3rd_party/SoftFloat-3e/source/extF80_roundToInt.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, 2017 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  extFloat80_t
    45   extF80_roundToInt( extFloat80_t a, uint_fast8_t roundingMode, bool exact )
    46  {
    47      union { struct extFloat80M s; extFloat80_t f; } uA;
    48      uint_fast16_t uiA64, signUI64;
    49      int_fast32_t exp;
    50      uint_fast64_t sigA;
    51      uint_fast16_t uiZ64;
    52      uint_fast64_t sigZ;
    53      struct exp32_sig64 normExpSig;
    54      struct uint128 uiZ;
    55      uint_fast64_t lastBitMask, roundBitsMask;
    56      union { struct extFloat80M s; extFloat80_t f; } uZ;
    57  
    58      /*------------------------------------------------------------------------
    59      *------------------------------------------------------------------------*/
    60      uA.f = a;
    61      uiA64 = uA.s.signExp;
    62      signUI64 = uiA64 & packToExtF80UI64( 1, 0 );
    63      exp = expExtF80UI64( uiA64 );
    64      sigA = uA.s.signif;
    65      /*------------------------------------------------------------------------
    66      *------------------------------------------------------------------------*/
    67      if ( !(sigA & UINT64_C( 0x8000000000000000 )) && (exp != 0x7FFF) ) {
    68          if ( !sigA ) {
    69              uiZ64 = signUI64;
    70              sigZ = 0;
    71              goto uiZ;
    72          }
    73          normExpSig = softfloat_normSubnormalExtF80Sig( sigA );
    74          exp += normExpSig.exp;
    75          sigA = normExpSig.sig;
    76      }
    77      /*------------------------------------------------------------------------
    78      *------------------------------------------------------------------------*/
    79      if ( 0x403E <= exp ) {
    80          if ( exp == 0x7FFF ) {
    81              if ( sigA & UINT64_C( 0x7FFFFFFFFFFFFFFF ) ) {
    82                  uiZ = softfloat_propagateNaNExtF80UI( uiA64, sigA, 0, 0 );
    83                  uiZ64 = uiZ.v64;
    84                  sigZ  = uiZ.v0;
    85                  goto uiZ;
    86              }
    87              sigZ = UINT64_C( 0x8000000000000000 );
    88          } else {
    89              sigZ = sigA;
    90          }
    91          uiZ64 = signUI64 | exp;
    92          goto uiZ;
    93      }
    94      if ( exp <= 0x3FFE ) {
    95          if ( exact ) softfloat_exceptionFlags |= softfloat_flag_inexact;
    96          switch ( roundingMode ) {
    97           case softfloat_round_near_even:
    98              if ( !(sigA & UINT64_C( 0x7FFFFFFFFFFFFFFF )) ) break;
    99           case softfloat_round_near_maxMag:
   100              if ( exp == 0x3FFE ) goto mag1;
   101              break;
   102           case softfloat_round_min:
   103              if ( signUI64 ) goto mag1;
   104              break;
   105           case softfloat_round_max:
   106              if ( !signUI64 ) goto mag1;
   107              break;
   108  #ifdef SOFTFLOAT_ROUND_ODD
   109           case softfloat_round_odd:
   110              goto mag1;
   111  #endif
   112          }
   113          uiZ64 = signUI64;
   114          sigZ  = 0;
   115          goto uiZ;
   116       mag1:
   117          uiZ64 = signUI64 | 0x3FFF;
   118          sigZ  = UINT64_C( 0x8000000000000000 );
   119          goto uiZ;
   120      }
   121      /*------------------------------------------------------------------------
   122      *------------------------------------------------------------------------*/
   123      uiZ64 = signUI64 | exp;
   124      lastBitMask = (uint_fast64_t) 1<<(0x403E - exp);
   125      roundBitsMask = lastBitMask - 1;
   126      sigZ = sigA;
   127      if ( roundingMode == softfloat_round_near_maxMag ) {
   128          sigZ += lastBitMask>>1;
   129      } else if ( roundingMode == softfloat_round_near_even ) {
   130          sigZ += lastBitMask>>1;
   131          if ( !(sigZ & roundBitsMask) ) sigZ &= ~lastBitMask;
   132      } else if (
   133          roundingMode == (signUI64 ? softfloat_round_min : softfloat_round_max)
   134      ) {
   135          sigZ += roundBitsMask;
   136      }
   137      sigZ &= ~roundBitsMask;
   138      if ( !sigZ ) {
   139          ++uiZ64;
   140          sigZ = UINT64_C( 0x8000000000000000 );
   141      }
   142      if ( sigZ != sigA ) {
   143  #ifdef SOFTFLOAT_ROUND_ODD
   144          if ( roundingMode == softfloat_round_odd ) sigZ |= lastBitMask;
   145  #endif
   146          if ( exact ) softfloat_exceptionFlags |= softfloat_flag_inexact;
   147      }
   148   uiZ:
   149      uZ.s.signExp = uiZ64;
   150      uZ.s.signif = sigZ;
   151      return uZ.f;
   152  
   153  }
   154