softfloat/f64_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 float64_t f64_mul( float64_t a, float64_t b )
  45 {
  46     union ui64_f64 uA;
  47     uint_fast64_t uiA;
  48     bool signA;
  49     int_fast16_t expA;
  50     uint_fast64_t sigA;
  51     union ui64_f64 uB;
  52     uint_fast64_t uiB;
  53     bool signB;
  54     int_fast16_t expB;
  55     uint_fast64_t sigB;
  56     bool signZ;
  57     uint_fast64_t magBits;
  58     struct exp16_sig64 normExpSig;
  59     int_fast16_t expZ;
  60 #ifdef SOFTFLOAT_FAST_INT64
  61     struct uint128 sig128Z;
  62 #else
  63     uint32_t sig128Z[4];
  64 #endif
  65     uint_fast64_t sigZ, uiZ;
  66     union ui64_f64 uZ;
  67
  68     /*------------------------------------------------------------------------
  69     *------------------------------------------------------------------------*/
  70     uA.f = a;
  71     uiA = uA.ui;
  72     signA = signF64UI( uiA );
  73     expA  = expF64UI( uiA );
  74     sigA  = fracF64UI( uiA );
  75     uB.f = b;
  76     uiB = uB.ui;
  77     signB = signF64UI( uiB );
  78     expB  = expF64UI( uiB );
  79     sigB  = fracF64UI( uiB );
  80     signZ = signA ^ signB;
  81     /*------------------------------------------------------------------------
  82     *------------------------------------------------------------------------*/
  83     if ( expA == 0x7FF ) {
  84         if ( sigA || ((expB == 0x7FF) && sigB) ) goto propagateNaN;
  85         magBits = expB | sigB;
  86         goto infArg;
  87     }
  88     if ( expB == 0x7FF ) {
  89         if ( sigB ) goto propagateNaN;
  90         magBits = expA | sigA;
  91         goto infArg;
  92     }
  93     /*------------------------------------------------------------------------
  94     *------------------------------------------------------------------------*/
  95     if ( ! expA ) {
  96         if ( ! sigA ) goto zero;
  97         normExpSig = softfloat_normSubnormalF64Sig( sigA );
  98         expA = normExpSig.exp;
  99         sigA = normExpSig.sig;
 100     }
 101     if ( ! expB ) {
 102         if ( ! sigB ) goto zero;
 103         normExpSig = softfloat_normSubnormalF64Sig( sigB );
 104         expB = normExpSig.exp;
 105         sigB = normExpSig.sig;
 106     }
 107     /*------------------------------------------------------------------------
 108     *------------------------------------------------------------------------*/
 109     expZ = expA + expB - 0x3FF;
 110     sigA = (sigA | UINT64_C( 0x0010000000000000 ))<<10;
 111     sigB = (sigB | UINT64_C( 0x0010000000000000 ))<<11;
 112 #ifdef SOFTFLOAT_FAST_INT64
 113     sig128Z = softfloat_mul64To128( sigA, sigB );
 114     sigZ = sig128Z.v64 | (sig128Z.v0 != 0);
 115 #else
 116     softfloat_mul64To128M( sigA, sigB, sig128Z );
 117     sigZ =
 118         (uint64_t) sig128Z[indexWord( 4, 3 )]<<32 | sig128Z[indexWord( 4, 2 )];
 119     if ( sig128Z[indexWord( 4, 1 )] || sig128Z[indexWord( 4, 0 )] ) sigZ |= 1;
 120 #endif
 121     if ( sigZ < UINT64_C( 0x4000000000000000 ) ) {
 122         --expZ;
 123         sigZ <<= 1;
 124     }
 125     return softfloat_roundPackToF64( signZ, expZ, sigZ );
 126     /*------------------------------------------------------------------------
 127     *------------------------------------------------------------------------*/
 128  propagateNaN:
 129     uiZ = softfloat_propagateNaNF64UI( uiA, uiB );
 130     goto uiZ;
 131     /*------------------------------------------------------------------------
 132     *------------------------------------------------------------------------*/
 133  infArg:
 134     if ( ! magBits ) {
 135         softfloat_raiseFlags( softfloat_flag_invalid );
 136         uiZ = defaultNaNF64UI;
 137     } else {
 138         uiZ = packToF64UI( signZ, 0x7FF, 0 );
 139     }
 140     goto uiZ;
 141     /*------------------------------------------------------------------------
 142     *------------------------------------------------------------------------*/
 143  zero:
 144     uiZ = packToF64UI( signZ, 0, 0 );
 145  uiZ:
 146     uZ.ui = uiZ;
 147     return uZ.f;
 148
 149 }
 150