home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Languguage OS 2
/
Languguage OS II Version 10-94 (Knowledge Media)(1994).ISO
/
gnu
/
libg_261.zip
/
libg_261
/
libg++
/
src
/
Fix.cc
< prev
next >
Wrap
C/C++ Source or Header
|
1994-08-12
|
13KB
|
664 lines
// This may look like C code, but it is really -*- C++ -*-
/*
Copyright (C) 1989 Free Software Foundation
written by Doug Lea (dl@rocky.oswego.edu)
This file is part of the GNU C++ Library. This library is free
software; you can redistribute it and/or modify it under the terms of
the GNU Library General Public License as published by the Free
Software Foundation; either version 2 of the License, or (at your
option) any later version. This library 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 Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free Software
Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/
//
// Fix.cc : variable length fixed point data type class functions
//
#ifdef __GNUG__
#pragma implementation
#endif
#include <Fix.h>
#include <std.h>
#include <Obstack.h>
#include <AllocRing.h>
#include <strstream.h>
// member constants
const _G_uint16_t Fix::min_length;
const _G_uint16_t Fix::max_length;
const double Fix::min_value;
const double Fix::max_value;
// default parameters
_G_uint16_t Fix::default_length = 16;
int Fix::default_print_width = 8;
Fix::PEH Fix::overflow_handler = Fix::overflow_saturate;
Fix::Rep Fix::Rep_0 = { 16, 1, 1, { 0 } };
Fix::Rep Fix::Rep_m1 = { 16, 1, 1, { 0x8000 } };
Fix::Rep Fix::Rep_quotient_bump = { 16, 1, 1, { 0x4000 } };
// error handling
void
Fix::default_error_handler(const char* msg)
{
cerr << "Fix: " << msg << "\n";
abort();
}
void
Fix::default_range_error_handler(const char* msg)
{
cerr << "Fix: range error in " << msg << "\n";
//abort();
}
one_arg_error_handler_t
Fix::error_handler = Fix::default_error_handler,
Fix::range_error_handler = Fix::default_range_error_handler;
one_arg_error_handler_t
Fix::set_error_handler(one_arg_error_handler_t f)
{
one_arg_error_handler_t old = error_handler;
error_handler = f;
return old;
}
one_arg_error_handler_t
Fix::set_range_error_handler(one_arg_error_handler_t f)
{
one_arg_error_handler_t old = range_error_handler;
range_error_handler = f;
return old;
}
void
Fix::error(const char* msg)
{
error_handler(msg);
}
void
Fix::range_error(const char* msg)
{
range_error_handler(msg);
}
// Fix::Rep allocation and initialization functions
static inline Fix::Rep*
_new_Fix(_G_uint16_t len)
{
int siz = (((_G_uint32_t) len + 15) >> 4);
if (siz <= 0) siz = 1;
unsigned int allocsiz = (sizeof(Fix::Rep) + (siz - 1) * sizeof(_G_uint16_t));
Fix::Rep* z = (Fix::Rep*)(new char[allocsiz]);
memset(z, 0, allocsiz);
z->len = len;
z->siz = siz;
z->ref = 1;
return z;
}
Fix::Rep*
Fix::new_Fix(_G_uint16_t len)
{
return _new_Fix(len);
}
Fix::Rep*
Fix::new_Fix(_G_uint16_t len, const Rep* x)
{
Rep* z = _new_Fix(len);
return copy(x,z);
}
Fix::Rep*
Fix::new_Fix(_G_uint16_t len, double d)
{
Rep* z = _new_Fix(len);
if ( d == max_value )
{
z->s[0] = 0x7fff;
for ( int i=1; i < z->siz; i++ )
z->s[i] = 0xffff;
}
else if ( d < min_value || d > max_value )
range_error("declaration");
else
{
if (d < 0)
d += 2.0;
d *= 32768;
for ( int i=0; i < z->siz; i++ )
{
z->s[i] = (_G_uint16_t )d;
d -= z->s[i];
d *= 65536;
}
if ( d >= 32768 )
z->s[z->siz-1]++;
}
mask(z);
return z;
}
// convert to a double
double
value(const Fix& x)
{
double d = 0.0;
for ( int i=x.rep->siz-1; i >= 0; i-- )
{
d += x.rep->s[i];
d *= 1./65536.;
}
d *= 2.;
return d < 1. ? d : d - 2.;
}
// extract mantissa to Integer
Integer
mantissa(const Fix& x)
{
Integer a = 1, b=1;
for ( int i=0; i < x.rep->siz; i++ )
{
a <<= 16;
a += x.rep->s[i];
b <<= 16;
}
return a-b;
}
// comparison functions
inline static int
docmp(const _G_uint16_t* x, const _G_uint16_t* y, int siz)
{
int diff = (_G_int16_t )*x - (_G_int16_t )*y;
while ( --siz && !diff )
diff = (_G_int32_t )(_G_uint32_t )*++x - (_G_int32_t )(_G_uint32_t )*++y;
return diff;
}
inline static int
docmpz(const _G_uint16_t* x, int siz)
{
while ( siz-- )
if ( *x++ ) return 1;
return 0;
}
int
Fix::compare(const Rep* x, const Rep* y)
{
if ( x->siz == y->siz )
return docmp(x->s, y->s, x->siz);
else
{
int r;
const Rep* longer, *shorter;
if ( x->siz > y->siz )
{
longer = x;
shorter = y;
r = 1;
}
else
{
longer = y;
shorter = x;
r = -1;
}
int diff = docmp(x->s, y->s, shorter->siz);
if ( diff )
return diff;
else if ( docmpz(&longer->s[shorter->siz], longer->siz-shorter->siz) )
return r;
else
return 0;
}
}
// arithmetic functions
Fix::Rep*
Fix::add(const Rep* x, const Rep* y, Rep* r)
{
_G_uint16_t xsign = x->s[0], ysign = y->s[0];
const Rep* longer, *shorter;
if ( x->len >= y->len )
longer = x, shorter = y;
else
longer = y, shorter = x;
if ( r == NULL )
r = new_Fix(longer->len);
for ( int i=r->siz-1; i >= longer->siz; i-- )
r->s[i] = 0;
for ( ; i >= shorter->siz; i-- )
r->s[i] = longer->s[i];
_G_uint32_t sum = 0, carry = 0;
for ( ; i >= 0; i-- )
{
sum = carry + (_G_uint32_t )x->s[i] + (_G_uint32_t )y->s[i];
carry = sum >> 16;
r->s[i] = sum;
}
if ( (xsign ^ sum) & (ysign ^ sum) & 0x8000 )
overflow_handler(r);
return r;
}
Fix::Rep*
Fix::subtract(const Rep* x, const Rep* y, Rep* r)
{
_G_uint16_t xsign = x->s[0], ysign = y->s[0];
const Rep* longer, *shorter;
if ( x->len >= y->len )
longer = x, shorter = y;
else
longer = y, shorter = x;
if ( r == NULL )
r = new_Fix(longer->len);
for ( int i=r->siz-1; i >= longer->siz; i-- )
r->s[i] = 0;
for ( ; i >= shorter->siz; i-- )
r->s[i] = (longer == x ? x->s[i] : -y->s[i]);
_G_int16_t carry = 0;
_G_uint32_t sum = 0;
for ( ; i >= 0; i-- )
{
sum = (_G_int32_t )carry + (_G_uint32_t )x->s[i] - (_G_uint32_t )y->s[i];
carry = sum >> 16;
r->s[i] = sum;
}
if ( (xsign ^ sum) & (~ysign ^ sum) & 0x8000 )
overflow_handler(r);
return r;
}
Fix::Rep*
Fix::multiply(const Rep* x, const Rep* y, Rep* r)
{
if ( r == NULL )
r = new_Fix(x->len + y->len);
int xsign = x->s[0] & 0x8000,
ysign = y->s[0] & 0x8000;
Fix X(x->len), Y(y->len);
if ( xsign )
x = negate(x,X.rep);
if ( ysign )
y = negate(y,Y.rep);
for ( int i=0; i < r->siz; i++ )
r->s[i] = 0;
for ( i=x->siz-1; i >= 0; i-- )
{
_G_uint32_t carry = 0;
for ( int j=y->siz-1; j >= 0; j-- )
{
int k = i + j + 1;
_G_uint32_t a = (_G_uint32_t )x->s[i] * (_G_uint32_t )y->s[j];
_G_uint32_t b = ((a << 1) & 0xffff) + carry;
if ( k < r->siz )
{
b += r->s[k];
r->s[k] = b;
}
if ( k < (int)r->siz + 1 )
carry = (a >> 15) + (b >> 16);
}
r->s[i] = carry;
}
if ( xsign != ysign )
negate(r,r);
return r;
}
Fix::Rep*
Fix::multiply(const Rep* x, int y, Rep* r)
{
if ( y != (_G_int16_t )y )
range_error("multiply by int -- int too large");
if ( r == NULL )
r = new_Fix(x->len);
for ( int i=r->siz-1; i >= x->siz; i-- )
r->s[i] = 0;
_G_int32_t a, carry = 0;
for ( ; i > 0; i-- )
{
a = (_G_int32_t) (_G_uint32_t )x->s[i] * y + carry;
r->s[i] = a;
carry = a >> 16; // assumes arithmetic right shift
}
a = (_G_int32_t) (_G_int16_t )x->s[0] * y + carry;
r->s[0] = a;
a &= 0xffff8000L;
if ( a != (_G_int32_t)0xffff8000L && a != (_G_int32_t)0L ) {
r->s[0] = 0x8000 ^ x->s[0] ^ y;
overflow_handler(r);
}
return r;
}
Fix::Rep*
Fix::divide(const Rep* x, const Rep* y, Rep* q, Rep* r)
{
int xsign = x->s[0] & 0x8000,
ysign = y->s[0] & 0x8000;
if ( q == NULL )
q = new_Fix(x->len);
copy(&Rep_0,q);
if ( r == NULL )
r = new_Fix(x->len + y->len - 1);
if ( xsign )
negate(x,r);
else
copy(x,r);
Fix Y(y->len);
Rep* y2 = ( ysign ? negate(y,Y.rep) : copy(y,Y.rep) );
if ( !compare(y2) )
range_error("division -- division by zero");
else if ( compare(x,y2) >= 0 )
if ( compare(x,y2) == 0 && (xsign ^ ysign) != 0 )
{
copy(&Rep_m1,q);
copy(&Rep_0,r);
}
else
range_error("division");
else
{
Rep* t;
Fix S(r->len),
W(q->len,&Rep_quotient_bump);
for ( int i=1; i < q->len; i++ )
{
shift(y2,-1,y2);
subtract(r,y2,S.rep);
int s_status = compare(S.rep);
if ( s_status == 0 )
{
t = r, r = S.rep, S.rep = t;
break;
}
else if ( s_status > 0 )
{
t = r, r = S.rep, S.rep = t;
add(q,W.rep,q);
}
shift(W.rep,-1,W.rep);
}
if ( xsign ^ ysign )
negate(q,q);
}
return q;
}
Fix::Rep*
Fix::shift(const Rep* x, int y, Rep* r)
{
if ( r == NULL )
r = new_Fix(x->len);
if ( y == 0 )
{
copy (x, r);
return r;
}
int ay = abs((_G_int32_t) y),
ayh = ay >> 4,
ayl = ay & 0x0f;
int xl, u, ilow, ihigh;
_G_uint16_t *rs;
const _G_uint16_t *xsl, *xsr;
if ( y > 0 )
{
rs = r->s;
xsl = x->s + ayh;
xsr = xsl + 1;
xl = ayl;
u = 1;
ihigh = x->siz - ayh - 1;
ilow = 0;
}
else
{
rs = &r->s[r->siz - 1];
xsr = &x->s[r->siz - 1] - ayh;
xsl = xsr - 1;
xl = 16 - ayl;
u = -1;
ihigh = r->siz - ayh - 1;
ilow = ihigh - x->siz;
}
int xr = 16 - xl;
_G_uint16_t xrmask = 0xffffL >> xr;
for ( int i=0; i < ilow; i++, rs+=u, xsl+=u, xsr+=u )
*rs = 0;
for ( ; i < ihigh; i++, rs+=u, xsl+=u, xsr+=u )
*rs = (*xsl << xl) + ((*xsr >> xr) & xrmask);
*rs = (y > 0 ? (*xsl << xl) : ((*xsr >> xr) & xrmask));
rs += u;
for ( ; ++i < r->siz; rs+=u )
*rs = 0;
return r;
}
Fix::Rep*
Fix::negate(const Rep* x, Rep* r)
{
if ( r == NULL )
r = new_Fix(x->len);
_G_uint32_t carry = 1;
for ( int i=r->siz-1; i >= x->siz; i-- )
r->s[i] = 0;
for ( ; i >= 0; i-- )
{
_G_uint32_t a = (_G_uint16_t )~x->s[i] + carry; // bug work-around
r->s[i] = a;
carry = a >> 16;
}
return r;
}
// io functions
Fix
atoF(const char* a, int len)
{
return Fix(len,atof(a));
}
extern AllocRing _libgxx_fmtq;
void
Fix::printon(ostream& s, int width) const
{
double val = value(*this);
int old_precision = s.precision(width-3);
_G_int32_t old_flags = s.setf(ios::fixed, ios::fixed|ios::scientific);
if (val >= 0)
s << ' ';
s.width(width-2);
s << val;
s.precision(old_precision);
s.flags(old_flags);
}
char*
Ftoa(Fix& x, int width)
{
int wrksiz = width + 2;
char *fmtbase = (char *) _libgxx_fmtq.alloc(wrksiz);
ostrstream stream(fmtbase, wrksiz);
x.printon(stream, width);
stream << ends;
return fmtbase;
}
extern Obstack _libgxx_io_ob;
Fix
Fix::operator %= (int y)
{
Fix r((int )rep->len + y, *this); return *this = r;
}
istream&
operator >> (istream& s, Fix& y)
{
int got_one = 0;
if (!s.ipfx(0))
{
s.clear(ios::failbit|s.rdstate()); // Redundant if using GNU iostreams.
return s;
}
char sign = 0, point = 0;
char ch;
s >> ws;
if (!s.good())
{
s.clear(ios::failbit|s.rdstate());
return s;
}
while (s.get(ch))
{
if (ch == '-')
{
if (sign == 0)
{
sign = 1;
_libgxx_io_ob.grow(ch);
}
else
break;
}
if (ch == '.')
{
if (point == 0)
{
point = 1;
_libgxx_io_ob.grow(ch);
}
else
break;
}
else if (ch >= '0' && ch <= '9')
{
got_one = 1;
_libgxx_io_ob.grow(ch);
}
else
break;
}
char * p = (char*)(_libgxx_io_ob.finish(0));
if (s.good())
s.putback(ch);
if (!got_one)
s.clear(ios::failbit|s.rdstate());
else
y = atoF(p);
_libgxx_io_ob.free(p);
return s;
}
void
show(const Fix& x)
{
cout << "len = " << x.rep->len << "\n";
cout << "siz = " << x.rep->siz << "\n";
cout << "ref = " << x.rep->ref << "\n";
cout << "man = ";
#ifdef _OLD_STREAMS
cout << Itoa(mantissa(x),16,4*x.rep->siz);
#else
int old_flags = cout.setf(ios::hex, ios::hex|ios::dec|ios::oct);
cout.width(4*x.rep->siz);
cout << mantissa(x);
cout.setf(old_flags, ios::hex|ios::dec|ios::oct);
#endif
cout << "\n";
cout << "val = " << value(x) << "\n";
}
// parameter setting operations
Fix::PEH Fix::set_overflow_handler(PEH new_handler)
{
PEH old_handler = overflow_handler;
overflow_handler = new_handler;
return old_handler;
}
int
Fix::set_default_length(int newlen)
{
_G_uint16_t oldlen = default_length;
if ( newlen < min_length || newlen > max_length )
error("illegal length in Fix::set_default_length");
default_length = newlen;
return oldlen;
}
// overflow handlers
void
Fix::overflow_saturate(Rep* r)
{
if ( (_G_int16_t) r->s[0] > 0 )
{
r->s[0] = 0x8000;
for ( int i=1; i < r->siz; i++ )
r->s[i] = 0;
}
else
{
r->s[0] = 0x7fff;
for ( int i = 1; i < (int)r->siz; i++ )
r->s[i] = 0xffff;
mask(r);
}
}
void
Fix::overflow_wrap(Rep*)
{}
void
Fix::overflow_warning_saturate(Rep* r)
{
overflow_warning(r);
overflow_saturate(r);
}
void
Fix::overflow_warning(Rep*)
{
cerr << "Fix: overflow warning\n";
}
void
Fix::overflow_error(Rep*)
{
cerr << "Fix: overflow error\n";
abort();
}