softfloat/source/extF80M_roundToInt.c

   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 #ifdef SOFTFLOAT_FAST_INT64
  45
  46 void
  47  extF80M_roundToInt(
  48      const extFloat80_t *aPtr,
  49      uint_fast8_t roundingMode,
  50      bool exact,
  51      extFloat80_t *zPtr
  52  )
  53 {
  54
  55     *zPtr = extF80_roundToInt( *aPtr, roundingMode, exact );
  56
  57 }
  58
  59 #else
  60
  61 void
  62  extF80M_roundToInt(
  63      const extFloat80_t *aPtr,
  64      uint_fast8_t roundingMode,
  65      bool exact,
  66      extFloat80_t *zPtr
  67  )
  68 {
  69     const struct extFloat80M *aSPtr;
  70     struct extFloat80M *zSPtr;
  71     uint_fast16_t uiA64, signUI64;
  72     int32_t exp;
  73     uint64_t sigA;
  74     uint_fast16_t uiZ64;
  75     uint64_t sigZ, lastBitMask, roundBitsMask;
  76
  77     /*------------------------------------------------------------------------
  78     *------------------------------------------------------------------------*/
  79     aSPtr = (const struct extFloat80M *) aPtr;
  80     zSPtr = (struct extFloat80M *) zPtr;
  81     /*------------------------------------------------------------------------
  82     *------------------------------------------------------------------------*/
  83     uiA64 = aSPtr->signExp;
  84     signUI64 = uiA64 & packToExtF80UI64( 1, 0 );
  85     exp = expExtF80UI64( uiA64 );
  86     sigA = aSPtr->signif;
  87     /*------------------------------------------------------------------------
  88     *------------------------------------------------------------------------*/
  89     if ( !(sigA & UINT64_C( 0x8000000000000000 )) && (exp != 0x7FFF) ) {
  90         if ( !sigA ) {
  91             uiZ64 = signUI64;
  92             sigZ = 0;
  93             goto uiZ;
  94         }
  95         exp += softfloat_normExtF80SigM( &sigA );
  96     }
  97     /*------------------------------------------------------------------------
  98     *------------------------------------------------------------------------*/
  99     if ( exp <= 0x3FFE ) {
 100         if ( exact ) softfloat_exceptionFlags |= softfloat_flag_inexact;
 101         switch ( roundingMode ) {
 102          case softfloat_round_near_even:
 103             if ( !(sigA & UINT64_C( 0x7FFFFFFFFFFFFFFF )) ) break;
 104          case softfloat_round_near_maxMag:
 105             if ( exp == 0x3FFE ) goto mag1;
 106             break;
 107          case softfloat_round_min:
 108             if ( signUI64 ) goto mag1;
 109             break;
 110          case softfloat_round_max:
 111             if ( !signUI64 ) goto mag1;
 112             break;
 113 #ifdef SOFTFLOAT_ROUND_ODD
 114          case softfloat_round_odd:
 115             goto mag1;
 116 #endif
 117         }
 118         uiZ64 = signUI64;
 119         sigZ = 0;
 120         goto uiZ;
 121      mag1:
 122         uiZ64 = signUI64 | 0x3FFF;
 123         sigZ = UINT64_C( 0x8000000000000000 );
 124         goto uiZ;
 125     }
 126     /*------------------------------------------------------------------------
 127     *------------------------------------------------------------------------*/
 128     if ( 0x403E <= exp ) {
 129         if ( exp == 0x7FFF ) {
 130             if ( sigA & UINT64_C( 0x7FFFFFFFFFFFFFFF ) ) {
 131                 softfloat_propagateNaNExtF80M( aSPtr, 0, zSPtr );
 132                 return;
 133             }
 134             sigZ = UINT64_C( 0x8000000000000000 );
 135         } else {
 136             sigZ = sigA;
 137         }
 138         uiZ64 = signUI64 | exp;
 139         goto uiZ;
 140     }
 141     /*------------------------------------------------------------------------
 142     *------------------------------------------------------------------------*/
 143     uiZ64 = signUI64 | exp;
 144     lastBitMask = (uint64_t) 1<<(0x403E - exp);
 145     roundBitsMask = lastBitMask - 1;
 146     sigZ = sigA;
 147     if ( roundingMode == softfloat_round_near_maxMag ) {
 148         sigZ += lastBitMask>>1;
 149     } else if ( roundingMode == softfloat_round_near_even ) {
 150         sigZ += lastBitMask>>1;
 151         if ( !(sigZ & roundBitsMask) ) sigZ &= ~lastBitMask;
 152     } else if (
 153         roundingMode == (signUI64 ? softfloat_round_min : softfloat_round_max)
 154     ) {
 155         sigZ += roundBitsMask;
 156     }
 157     sigZ &= ~roundBitsMask;
 158     if ( !sigZ ) {
 159         ++uiZ64;
 160         sigZ = UINT64_C( 0x8000000000000000 );
 161     }
 162     if ( sigZ != sigA ) {
 163 #ifdef SOFTFLOAT_ROUND_ODD
 164         if ( roundingMode == softfloat_round_odd ) sigZ |= lastBitMask;
 165 #endif
 166         if ( exact ) softfloat_exceptionFlags |= softfloat_flag_inexact;
 167     }
 168  uiZ:
 169     zSPtr->signExp = uiZ64;
 170     zSPtr->signif = sigZ;
 171     return;
 172
 173 }
 174
 175 #endif
 176