softfloat/f32_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, 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 float32_t f32_mul( 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     uint_fast32_t magBits;
  58     struct exp16_sig32 normExpSig;
  59     int_fast16_t expZ;
  60     uint_fast32_t sigZ, uiZ;
  61     union ui32_f32 uZ;
  62
  63     /*------------------------------------------------------------------------
  64     *------------------------------------------------------------------------*/
  65     uA.f = a;
  66     uiA = uA.ui;
  67     signA = signF32UI( uiA );
  68     expA  = expF32UI( uiA );
  69     sigA  = fracF32UI( uiA );
  70     uB.f = b;
  71     uiB = uB.ui;
  72     signB = signF32UI( uiB );
  73     expB  = expF32UI( uiB );
  74     sigB  = fracF32UI( uiB );
  75     signZ = signA ^ signB;
  76     /*------------------------------------------------------------------------
  77     *------------------------------------------------------------------------*/
  78     if ( expA == 0xFF ) {
  79         if ( sigA || ((expB == 0xFF) && sigB) ) goto propagateNaN;
  80         magBits = expB | sigB;
  81         goto infArg;
  82     }
  83     if ( expB == 0xFF ) {
  84         if ( sigB ) goto propagateNaN;
  85         magBits = expA | sigA;
  86         goto infArg;
  87     }
  88     /*------------------------------------------------------------------------
  89     *------------------------------------------------------------------------*/
  90     if ( ! expA ) {
  91         if ( ! sigA ) goto zero;
  92         normExpSig = softfloat_normSubnormalF32Sig( sigA );
  93         expA = normExpSig.exp;
  94         sigA = normExpSig.sig;
  95     }
  96     if ( ! expB ) {
  97         if ( ! sigB ) goto zero;
  98         normExpSig = softfloat_normSubnormalF32Sig( sigB );
  99         expB = normExpSig.exp;
 100         sigB = normExpSig.sig;
 101     }
 102     /*------------------------------------------------------------------------
 103     *------------------------------------------------------------------------*/
 104     expZ = expA + expB - 0x7F;
 105     sigA = (sigA | 0x00800000)<<7;
 106     sigB = (sigB | 0x00800000)<<8;
 107     sigZ = softfloat_shortShiftRightJam64( (uint_fast64_t) sigA * sigB, 32 );
 108     if ( sigZ < 0x40000000 ) {
 109         --expZ;
 110         sigZ <<= 1;
 111     }
 112     return softfloat_roundPackToF32( signZ, expZ, sigZ );
 113     /*------------------------------------------------------------------------
 114     *------------------------------------------------------------------------*/
 115  propagateNaN:
 116     uiZ = softfloat_propagateNaNF32UI( uiA, uiB );
 117     goto uiZ;
 118     /*------------------------------------------------------------------------
 119     *------------------------------------------------------------------------*/
 120  infArg:
 121     if ( ! magBits ) {
 122         softfloat_raiseFlags( softfloat_flag_invalid );
 123         uiZ = defaultNaNF32UI;
 124     } else {
 125         uiZ = packToF32UI( signZ, 0xFF, 0 );
 126     }
 127     goto uiZ;
 128     /*------------------------------------------------------------------------
 129     *------------------------------------------------------------------------*/
 130  zero:
 131     uiZ = packToF32UI( signZ, 0, 0 );
 132  uiZ:
 133     uZ.ui = uiZ;
 134     return uZ.f;
 135
 136 }
 137