softfloat/f128_mul.c

   1
   2 /*============================================================================
   3
   4 This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
   5 Package, Release 3d, 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 float128_t f128_mul( float128_t a, float128_t b )
  45 {
  46     union ui128_f128 uA;
  47     uint_fast64_t uiA64, uiA0;
  48     bool signA;
  49     int_fast32_t expA;
  50     struct uint128 sigA;
  51     union ui128_f128 uB;
  52     uint_fast64_t uiB64, uiB0;
  53     bool signB;
  54     int_fast32_t expB;
  55     struct uint128 sigB;
  56     bool signZ;
  57     uint_fast64_t magBits;
  58     struct exp32_sig128 normExpSig;
  59     int_fast32_t expZ;
  60     uint64_t sig256Z[4];
  61     uint_fast64_t sigZExtra;
  62     struct uint128 sigZ;
  63     struct uint128_extra sig128Extra;
  64     struct uint128 uiZ;
  65     union ui128_f128 uZ;
  66
  67     /*------------------------------------------------------------------------
  68     *------------------------------------------------------------------------*/
  69     uA.f = a;
  70     uiA64 = uA.ui.v64;
  71     uiA0  = uA.ui.v0;
  72     signA = signF128UI64( uiA64 );
  73     expA  = expF128UI64( uiA64 );
  74     sigA.v64 = fracF128UI64( uiA64 );
  75     sigA.v0  = uiA0;
  76     uB.f = b;
  77     uiB64 = uB.ui.v64;
  78     uiB0  = uB.ui.v0;
  79     signB = signF128UI64( uiB64 );
  80     expB  = expF128UI64( uiB64 );
  81     sigB.v64 = fracF128UI64( uiB64 );
  82     sigB.v0  = uiB0;
  83     signZ = signA ^ signB;
  84     /*------------------------------------------------------------------------
  85     *------------------------------------------------------------------------*/
  86     if ( expA == 0x7FFF ) {
  87         if (
  88             (sigA.v64 | sigA.v0) || ((expB == 0x7FFF) && (sigB.v64 | sigB.v0))
  89         ) {
  90             goto propagateNaN;
  91         }
  92         magBits = expB | sigB.v64 | sigB.v0;
  93         goto infArg;
  94     }
  95     if ( expB == 0x7FFF ) {
  96         if ( sigB.v64 | sigB.v0 ) goto propagateNaN;
  97         magBits = expA | sigA.v64 | sigA.v0;
  98         goto infArg;
  99     }
 100     /*------------------------------------------------------------------------
 101     *------------------------------------------------------------------------*/
 102     if ( ! expA ) {
 103         if ( ! (sigA.v64 | sigA.v0) ) goto zero;
 104         normExpSig = softfloat_normSubnormalF128Sig( sigA.v64, sigA.v0 );
 105         expA = normExpSig.exp;
 106         sigA = normExpSig.sig;
 107     }
 108     if ( ! expB ) {
 109         if ( ! (sigB.v64 | sigB.v0) ) goto zero;
 110         normExpSig = softfloat_normSubnormalF128Sig( sigB.v64, sigB.v0 );
 111         expB = normExpSig.exp;
 112         sigB = normExpSig.sig;
 113     }
 114     /*------------------------------------------------------------------------
 115     *------------------------------------------------------------------------*/
 116     expZ = expA + expB - 0x4000;
 117     sigA.v64 |= UINT64_C( 0x0001000000000000 );
 118     sigB = softfloat_shortShiftLeft128( sigB.v64, sigB.v0, 16 );
 119     softfloat_mul128To256M( sigA.v64, sigA.v0, sigB.v64, sigB.v0, sig256Z );
 120     sigZExtra = sig256Z[indexWord( 4, 1 )] | (sig256Z[indexWord( 4, 0 )] != 0);
 121     sigZ =
 122         softfloat_add128(
 123             sig256Z[indexWord( 4, 3 )], sig256Z[indexWord( 4, 2 )],
 124             sigA.v64, sigA.v0
 125         );
 126     if ( UINT64_C( 0x0002000000000000 ) <= sigZ.v64 ) {
 127         ++expZ;
 128         sig128Extra =
 129             softfloat_shortShiftRightJam128Extra(
 130                 sigZ.v64, sigZ.v0, sigZExtra, 1 );
 131         sigZ = sig128Extra.v;
 132         sigZExtra = sig128Extra.extra;
 133     }
 134     return
 135         softfloat_roundPackToF128( signZ, expZ, sigZ.v64, sigZ.v0, sigZExtra );
 136     /*------------------------------------------------------------------------
 137     *------------------------------------------------------------------------*/
 138  propagateNaN:
 139     uiZ = softfloat_propagateNaNF128UI( uiA64, uiA0, uiB64, uiB0 );
 140     goto uiZ;
 141     /*------------------------------------------------------------------------
 142     *------------------------------------------------------------------------*/
 143  infArg:
 144     if ( ! magBits ) {
 145         softfloat_raiseFlags( softfloat_flag_invalid );
 146         uiZ.v64 = defaultNaNF128UI64;
 147         uiZ.v0  = defaultNaNF128UI0;
 148         goto uiZ;
 149     }
 150     uiZ.v64 = packToF128UI64( signZ, 0x7FFF, 0 );
 151     goto uiZ0;
 152     /*------------------------------------------------------------------------
 153     *------------------------------------------------------------------------*/
 154  zero:
 155     uiZ.v64 = packToF128UI64( signZ, 0, 0 );
 156  uiZ0:
 157     uiZ.v0 = 0;
 158  uiZ:
 159     uZ.ui = uiZ;
 160     return uZ.f;
 161
 162 }
 163