/*
**
** BITWISE.C Bit-wise operations on floating point numbers.
**
** Written 11-15-92 in ANSI C
**
** Eval is a floating point expression evaluator.
** This file last updated in version 1.10
** For the version number, see eval.h
** Copyright (C) 1993 Will Menninger
**
** This program is free software; you can redistribute it and/or modify it
** under the terms of the GNU General Public License as published by the
** Free Software Foundation; either version 2 of the License, or any
** later version.
**
** This program is distributed in the hope that it will be useful, but
** WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
** General Public License for more details.
**
** You should have received a copy of the GNU General Public License along
** with this program; if not, write to the Free Software Foundation, Inc.,
** 675 Mass Ave, Cambridge, MA 02139, USA.
**
** The author until 9/93 can be contacted at:
** e-mail: willus@ilm.pfc.mit.edu
** U.S. mail: Will Menninger, 45 River St., #2, Boston, MA 02108-1124
**
**
*/
#include "eval.h"
#define DATASIZE ((DBL_MANT_DIG>>3)+2)
typedef unsigned char uchar;
typedef struct {
uchar data[DATASIZE];
int sign;
int mask;
int numbits;
int exponent;
int mi;
} BITARRAY, *BITARRAYPTR;
static void dbl_to_ba(double val,BITARRAYPTR ba);
static double ba_to_dbl(BITARRAYPTR ba);
static void change_exp(BITARRAYPTR ba,int newexp);
static void shift_right(BITARRAYPTR ba,int count);
static void shift_left(BITARRAYPTR ba,int count);
static void ba_negate(BITARRAYPTR ba);
static void ba_not(BITARRAYPTR ba);
#ifdef DEBUG
static void print_ba(BITARRAYPTR ba);
#endif
double not(double val)
{
BITARRAY ba;
dbl_to_ba(val,&ba);
ba_not(&ba);
ba_negate(&ba);
ba.sign=!ba.sign;
return(ba_to_dbl(&ba));
}
double or(double val1,double val2)
{
BITARRAY ba1,ba2;
int i;
dbl_to_ba(val1,&ba1);
dbl_to_ba(val2,&ba2);
if (ba1.exponent>ba2.exponent)
change_exp(&ba2,ba1.exponent);
else
change_exp(&ba1,ba2.exponent);
if (!ba1.sign)
ba_negate(&ba1);
if (!ba2.sign)
ba_negate(&ba2);
for (i=0;i<=ba1.mi;i++)
ba1.data[i]|=ba2.data[i];
ba1.data[ba1.mi]&=ba1.mask;
if (!ba1.sign || !ba2.sign)
{
ba_negate(&ba1);
ba1.sign=0;
}
else
ba1.sign=1;
return(ba_to_dbl(&ba1));
}
double and(double val1,double val2)
{
BITARRAY ba1,ba2;
int i;
dbl_to_ba(val1,&ba1);
dbl_to_ba(val2,&ba2);
if (ba1.exponent>ba2.exponent)
change_exp(&ba2,ba1.exponent);
else
change_exp(&ba1,ba2.exponent);
if (!ba1.sign)
ba_negate(&ba1);
if (!ba2.sign)
ba_negate(&ba2);
for (i=0;i<=ba1.mi;i++)
ba1.data[i]&=ba2.data[i];
ba1.data[ba1.mi]&=ba1.mask;
if (!ba1.sign && !ba2.sign)
{
ba_negate(&ba1);
ba1.sign=0;
}
else
ba1.sign=1;
return(ba_to_dbl(&ba1));
}
double xor(double val1,double val2)
{
BITARRAY ba1,ba2;
int i;
dbl_to_ba(val1,&ba1);
dbl_to_ba(val2,&ba2);
if (ba1.exponent>ba2.exponent)
change_exp(&ba2,ba1.exponent);
else
change_exp(&ba1,ba2.exponent);
if (!ba1.sign)
ba_negate(&ba1);
if (!ba2.sign)
ba_negate(&ba2);
for (i=0;i<=ba1.mi;i++)
ba1.data[i]^=ba2.data[i];
ba1.data[ba1.mi]&=ba1.mask;
if ((!ba1.sign && ba2.sign)||(ba1.sign && !ba2.sign))
{
ba_negate(&ba1);
ba1.sign=0;
}
else
ba1.sign=1;
return(ba_to_dbl(&ba1));
}
static void dbl_to_ba(double val,BITARRAYPTR ba)
{
int i,j,k,m;
double f;
ba->numbits=DBL_MANT_DIG-3;
ba->mask=0;
ba->mi=0;
ba->exponent=0;
ba->sign=(val>=0.);
val=fabs(val);
if (val>0.)
{
f=log(val)/log(2.);
f=floor(f)+1.;
ba->exponent=f;
f=val/pow(2.,f);
f=f+pow(2.,(double)-ba->numbits-1.);
if (f>=1.)
{
ba->exponent++;
f/=2.;
}
}
else
f=0.;
for (i=0;i<DATASIZE;i++)
ba->data[i]=0;
for (i=0,j=0,k=128;i<ba->numbits;i++)
{
f=f*2.;
if (f>=1.)
{
ba->data[j]|=k;
f-=1.;
}
k>>=1;
if (!k)
{
j++;
k=128;
}
}
if (k==128)
{
ba->mask=255;
ba->mi=j-1;
}
else
{
for (k<<=1,m=k;k<128;k<<=1,m|=k);
ba->mask=m;
ba->mi=j;
}
}
static double ba_to_dbl(BITARRAYPTR ba)
{
int i,j,k;
double val;
val=0.;
for (i=0,j=0,k=128;i<ba->numbits;i++,k>>=1)
{
if (!k)
{
k=128;
j++;
}
val=val*2.;
if (ba->data[j]&k)
val=val+1.;
}
val=val*pow(2.,(double)ba->exponent-ba->numbits);
return(ba->sign ? val : -val);
}
static void change_exp(BITARRAYPTR ba,int newexp)
{
if (newexp>ba->exponent)
shift_right(ba,newexp-ba->exponent);
else
shift_left(ba,ba->exponent-newexp);
ba->exponent=newexp;
}
static void shift_right(BITARRAYPTR ba,int count)
{
int i,j,k,m;
int smallshift;
int byteshift;
if (!count)
return;
if (count>=ba->numbits)
{
for (i=0;i<DATASIZE;i++)
ba->data[i]=0;
return;
}
smallshift=count&7;
if (smallshift)
{
m=1;
for (i=1;i<smallshift;i++)
m=(m<<1)|1;
k=0;
for (i=0;i<=ba->mi;i++)
{
j=ba->data[i];
if (i>0)
ba->data[i]=k|(j>>smallshift);
else
ba->data[i]=j>>smallshift;
k=(j&m)<<(8-smallshift);
}
}
byteshift=(count>>3);
if (byteshift)
{
for (i=ba->mi;i>=byteshift;i--)
ba->data[i]=ba->data[i-byteshift];
for (i=byteshift-1;i>=0;i--)
ba->data[i]=0;
}
ba->data[ba->mi]&=ba->mask;
}
static void shift_left(BITARRAYPTR ba,int count)
{
int i,j,k,m;
int smallshift;
int byteshift;
if (!count)
return;
if (count>=ba->numbits)
{
for (i=0;i<DATASIZE;i++)
ba->data[i]=0;
return;
}
smallshift=count&7;
if (smallshift)
{
m=128;
for (i=1;i<smallshift;i++)
m=(m>>1)|128;
k=0;
ba->data[ba->mi]&=ba->mask;
for (i=ba->mi;i>=0;i--)
{
j=ba->data[i];
if (i<ba->mi)
ba->data[i]=k|(j<<smallshift);
else
ba->data[i]=j<<smallshift;
k=(j&m)>>(8-smallshift);
}
}
byteshift=(count>>3);
if (byteshift)
{
for (i=0;i<=ba->mi-byteshift;i++)
ba->data[i]=ba->data[i+byteshift];
for (i=ba->mi-byteshift+1;i<=ba->mi;i++)
ba->data[i]=0;
}
ba->data[ba->mi]&=ba->mask;
}
static void ba_negate(BITARRAYPTR ba)
{
int i,j,k,one;
i=ba->numbits&7;
if (!i)
i=8;
k=128;
for (j=1;j<i;j++,k>>=1);
j=ba->mi;
one=0;
for (i=ba->numbits-1;i>=0;i--,k<<=1)
{
if (k>128)
{
k=1;
j--;
if (one)
break;
}
if (one)
ba->data[j]^=k;
else
if (ba->data[j]&k)
{
one=1;
if (i==ba->numbits-1)
ba->data[j]^=k;
}
}
if (i>0)
for (;j>=0;j--)
ba->data[j]=~ba->data[j];
}
static void ba_not(BITARRAYPTR ba)
{
int i;
for (i=0;i<=ba->mi;i++)
ba->data[i]=~ba->data[i];
ba->data[ba->mi]&=ba->mask;
}
#ifdef DEBUG
static void print_ba(BITARRAYPTR ba)
{
int i;
printf(ba->sign ? "+" : "-");
for (i=0;i<ba->mi;i++)
printf("%02X",(unsigned)ba->data[i]);
printf("%02X %d\n",(unsigned)ba->data[ba->mi]&ba->mask,
ba->exponent);
}
#endif
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