github.com/igggame/nebulas-go@v2.1.0+incompatible/nbre/3rd_party/SoftFloat-3e/source/f32_div.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  float32_t f32_div( float32_t a, float32_t b )
    45  {
    46      union ui32_f32 uA;
    47      uint_fast32_t uiA;
    48      bool signA;
    49      int_fast16_t expA;
    50      uint_fast32_t sigA;
    51      union ui32_f32 uB;
    52      uint_fast32_t uiB;
    53      bool signB;
    54      int_fast16_t expB;
    55      uint_fast32_t sigB;
    56      bool signZ;
    57      struct exp16_sig32 normExpSig;
    58      int_fast16_t expZ;
    59  #ifdef SOFTFLOAT_FAST_DIV64TO32
    60      uint_fast64_t sig64A;
    61      uint_fast32_t sigZ;
    62  #else
    63      uint_fast32_t sigZ;
    64      uint_fast64_t rem;
    65  #endif
    66      uint_fast32_t uiZ;
    67      union ui32_f32 uZ;
    68  
    69      /*------------------------------------------------------------------------
    70      *------------------------------------------------------------------------*/
    71      uA.f = a;
    72      uiA = uA.ui;
    73      signA = signF32UI( uiA );
    74      expA  = expF32UI( uiA );
    75      sigA  = fracF32UI( uiA );
    76      uB.f = b;
    77      uiB = uB.ui;
    78      signB = signF32UI( uiB );
    79      expB  = expF32UI( uiB );
    80      sigB  = fracF32UI( uiB );
    81      signZ = signA ^ signB;
    82      /*------------------------------------------------------------------------
    83      *------------------------------------------------------------------------*/
    84      if ( expA == 0xFF ) {
    85          if ( sigA ) goto propagateNaN;
    86          if ( expB == 0xFF ) {
    87              if ( sigB ) goto propagateNaN;
    88              goto invalid;
    89          }
    90          goto infinity;
    91      }
    92      if ( expB == 0xFF ) {
    93          if ( sigB ) goto propagateNaN;
    94          goto zero;
    95      }
    96      /*------------------------------------------------------------------------
    97      *------------------------------------------------------------------------*/
    98      if ( ! expB ) {
    99          if ( ! sigB ) {
   100              if ( ! (expA | sigA) ) goto invalid;
   101              softfloat_raiseFlags( softfloat_flag_infinite );
   102              goto infinity;
   103          }
   104          normExpSig = softfloat_normSubnormalF32Sig( sigB );
   105          expB = normExpSig.exp;
   106          sigB = normExpSig.sig;
   107      }
   108      if ( ! expA ) {
   109          if ( ! sigA ) goto zero;
   110          normExpSig = softfloat_normSubnormalF32Sig( sigA );
   111          expA = normExpSig.exp;
   112          sigA = normExpSig.sig;
   113      }
   114      /*------------------------------------------------------------------------
   115      *------------------------------------------------------------------------*/
   116      expZ = expA - expB + 0x7E;
   117      sigA |= 0x00800000;
   118      sigB |= 0x00800000;
   119  #ifdef SOFTFLOAT_FAST_DIV64TO32
   120      if ( sigA < sigB ) {
   121          --expZ;
   122          sig64A = (uint_fast64_t) sigA<<31;
   123      } else {
   124          sig64A = (uint_fast64_t) sigA<<30;
   125      }
   126      sigZ = sig64A / sigB;
   127      if ( ! (sigZ & 0x3F) ) sigZ |= ((uint_fast64_t) sigB * sigZ != sig64A);
   128  #else
   129      if ( sigA < sigB ) {
   130          --expZ;
   131          sigA <<= 8;
   132      } else {
   133          sigA <<= 7;
   134      }
   135      sigB <<= 8;
   136      sigZ = ((uint_fast64_t) sigA * softfloat_approxRecip32_1( sigB ))>>32;
   137      /*------------------------------------------------------------------------
   138      *------------------------------------------------------------------------*/
   139      sigZ += 2;
   140      if ( (sigZ & 0x3F) < 2 ) {
   141          sigZ &= ~3;
   142  #ifdef SOFTFLOAT_FAST_INT64
   143          rem = ((uint_fast64_t) sigA<<31) - (uint_fast64_t) sigZ * sigB;
   144  #else
   145          rem = ((uint_fast64_t) sigA<<32) - (uint_fast64_t) (sigZ<<1) * sigB;
   146  #endif
   147          if ( rem & UINT64_C( 0x8000000000000000 ) ) {
   148              sigZ -= 4;
   149          } else {
   150              if ( rem ) sigZ |= 1;
   151          }
   152      }
   153  #endif
   154      return softfloat_roundPackToF32( signZ, expZ, sigZ );
   155      /*------------------------------------------------------------------------
   156      *------------------------------------------------------------------------*/
   157   propagateNaN:
   158      uiZ = softfloat_propagateNaNF32UI( uiA, uiB );
   159      goto uiZ;
   160      /*------------------------------------------------------------------------
   161      *------------------------------------------------------------------------*/
   162   invalid:
   163      softfloat_raiseFlags( softfloat_flag_invalid );
   164      uiZ = defaultNaNF32UI;
   165      goto uiZ;
   166      /*------------------------------------------------------------------------
   167      *------------------------------------------------------------------------*/
   168   infinity:
   169      uiZ = packToF32UI( signZ, 0xFF, 0 );
   170      goto uiZ;
   171      /*------------------------------------------------------------------------
   172      *------------------------------------------------------------------------*/
   173   zero:
   174      uiZ = packToF32UI( signZ, 0, 0 );
   175   uiZ:
   176      uZ.ui = uiZ;
   177      return uZ.f;
   178  
   179  }
   180