Category : OS/2 Files
Archive   : GPPDEV8F.ZIP
Filename : VHMAP.CCP

 
Output of file : VHMAP.CCP contained in archive : GPPDEV8F.ZIP
// This may look like C code, but it is really -*- C++ -*-
/*
Copyright (C) 1988 Free Software Foundation
written by Doug Lea ([email protected])

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.
*/

#ifdef __GNUG__
#pragma implementation
#endif
#include "..VHMap.h"

/* codes for status fields */

#define EMPTYCELL 0
#define VALIDCELL 1
#define DELETEDCELL 2


VHMap::VHMap( dflt, unsigned int sz)
:Map(dflt)
{
tab = new [size = sz];
cont = new [size];
status = new char[size];
for (unsigned int i = 0; i < size; ++i) status[i] = EMPTYCELL;
}

VHMap::VHMap(VHMap& a) : Map(a.def)
{
tab = new [size = a.size];
cont = new [size];
status = new char[size];
for (unsigned int i = 0; i < size; ++i) status[i] = EMPTYCELL;
count = 0;
for (Pix p = a.first(); p; a.next(p)) (*this)[a.key(p)] = a.contents(p);
}


/*
* hashing method: double hash based on high bits of hash fct,
* followed by linear probe. Can't do too much better if table
* sizes not constrained to be prime.
*/


static inline unsigned int doublehashinc(unsigned int h, unsigned int s)
{
unsigned int dh = ((h / s) % s);
return (dh > 1)? dh : 1;
}

Pix VHMap::seek( key)
{
unsigned int hashval = HASH(key);
unsigned int h = hashval % size;
for (unsigned int i = 0; i <= size; ++i)
{
if (status[h] == EMPTYCELL)
return 0;
else if (status[h] == VALIDCELL && EQ(key, tab[h]))
return Pix(&tab[h]);
if (i == 0)
h = (h + doublehashinc(hashval, size)) % size;
else if (++h >= size)
h -= size;
}
return 0;
}


& VHMap::operator []( item)
{
if (size <= count + 1)
resize();

unsigned int bestspot = size;
unsigned int hashval = HASH(item);
unsigned int h = hashval % size;
for (unsigned int i = 0; i <= size; ++i)
{
if (status[h] == EMPTYCELL)
{
++count;
if (bestspot >= size) bestspot = h;
tab[bestspot] = item;
status[bestspot] = VALIDCELL;
cont[bestspot] = def;
return cont[bestspot];
}
else if (status[h] == DELETEDCELL)
{
if (bestspot >= size) bestspot = h;
}
else if (EQ(tab[h],item))
return cont[h];

if (i == 0)
h = (h + doublehashinc(hashval, size)) % size;
else if (++h >= size)
h -= size;
}

++count;
status[bestspot] = VALIDCELL;
tab[bestspot] = item;
cont[bestspot] = def;
return cont[bestspot];
}


void VHMap::del( key)
{
unsigned int hashval = HASH(key);
unsigned int h = hashval % size;
for (unsigned int i = 0; i <= size; ++i)
{
if (status[h] == EMPTYCELL)
return;
else if (status[h] == VALIDCELL && EQ(key, tab[h]))
{
status[h] = DELETEDCELL;
--count;
return;
}
if (i == 0)
h = (h + doublehashinc(hashval, size)) % size;
else if (++h >= size)
h -= size;
}
}


void VHMap::clear()
{
for (unsigned int i = 0; i < size; ++i) status[i] = EMPTYCELL;
count = 0;
}

void VHMap::resize(unsigned int newsize)
{
if (newsize <= count)
{
newsize = DEFAULT_INITIAL_CAPACITY;
while (newsize <= count) newsize <<= 1;
}
* oldtab = tab;
* oldcont = cont;
char* oldstatus = status;
unsigned int oldsize = size;
tab = new [size = newsize];
cont = new [size];
status = new char[size];
for (unsigned int i = 0; i < size; ++i) status[i] = EMPTYCELL;
count = 0;
for (i = 0; i < oldsize; ++i)
if (oldstatus[i] == VALIDCELL)
(*this)[oldtab[i]] = oldcont[i];
delete [] oldtab;
delete [] oldcont;
delete oldstatus;
}

Pix VHMap::first()
{
for (unsigned int pos = 0; pos < size; ++pos)
if (status[pos] == VALIDCELL) return Pix(&tab[pos]);
return 0;
}

void VHMap::next(Pix& i)
{
if (i == 0) return;
unsigned int pos = ((unsigned)i - (unsigned)tab) / sizeof() + 1;
for (; pos < size; ++pos)
if (status[pos] == VALIDCELL)
{
i = Pix(&tab[pos]);
return;
}
i = 0;
}


int VHMap::OK()
{
int v = tab != 0;
v &= status != 0;
int n = 0;
for (unsigned int i = 0; i < size; ++i)
{
if (status[i] == VALIDCELL) ++n;
else if (status[i] != DELETEDCELL && status[i] != EMPTYCELL)
v = 0;
}
v &= n == count;
if (!v) error("invariant failure");
return v;
}


  3 Responses to “Category : OS/2 Files
Archive   : GPPDEV8F.ZIP
Filename : VHMAP.CCP

  1. Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!

  2. This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.

  3. But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/