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// Probabilistic reachability set storage -*- c++ -*-
#ifdef __GNUC__
# pragma implementation
#endif // __GNUC__
#include "HashGraph.h"
#include "ByteBuffer.h"
#include <stdlib.h>
#include <assert.h>
#include <time.h>
/** @file HashGraph.C
* Transient, probabilistic reachability set storage
*/
/* Copyright 2001-2002 Marko Mkel (msmakela@tcs.hut.fi).
This file is part of MARIA, a reachability analyzer and model checker
for high-level Petri nets.
MARIA 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, or (at your option)
any later version.
MARIA 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.
The GNU General Public License is often shipped with GNU software, and
is generally kept in a file called COPYING or LICENSE. If you do not
have a copy of the license, write to the Free Software Foundation,
59 Temple Place, Suite 330, Boston, MA 02111 USA. */
/** Number of bits size_t holds */
#define SIZE_T_BIT (sizeof (size_t) * CHAR_BIT)
/** primes[x] == prime closest to 32 << x */
static unsigned
primes[] = {
0x1f,
0x3d,
0x7f,
0x101,
0x1fd,
0x3fd,
0x805,
0xffd,
0x1fff,
0x3ffd,
0x8003,
0xfff1,
0x1ffff,
0x3fffb,
0x7ffff,
0xffffd,
0x1ffff7,
0x3ffffd,
0x7ffff1,
0xfffffd,
0x2000023,
0x3fffffb,
0x800001d,
0x10000003,
0x1ffffffd,
0x40000003,
0x7fffffff,
0xfffffffb
};
HashGraph::~HashGraph ()
{
for (unsigned s = myNumTables; s--; ) {
free (myHashes[s]);
free (myHashers[s]);
}
free (myHashes);
free (myHashers);
}
bool
HashGraph::init (unsigned numTables,
unsigned& funcSize,
unsigned& hashSize)
{
assert (!myHashes && !myHashers && !myNumTables && !getNumStates ());
if (!openFile ())
return false;
unsigned s;
/* round the hash function size to the next power of 2 */
for (s = 2; s < funcSize && sizeof (size_t) * s << 1; s <<= 1);
funcSize = s;
/* round the hash table size to the closest prime in our table */
for (s = 0; s < ((sizeof primes) / sizeof *primes) - 1; s++)
if (primes[s] >= hashSize)
break;
hashSize = primes[s];
s = 1 + (hashSize - 1) / SIZE_T_BIT;
/* allocate the tables */
if (!(myHashers =
static_cast<size_t**>(calloc (numTables, sizeof *myHashers))) ||
!(myHashes =
static_cast<size_t**>(calloc (numTables, sizeof *myHashes)))) {
failure:
if (myHashers) free (myHashers), myHashers = 0;
if (myHashes) free (myHashes), myHashes = 0;
return false;
}
unsigned t;
for (t = numTables; t--; ) {
if (!(myHashers[t] =
static_cast<size_t*>(calloc (funcSize, sizeof *myHashers[t]))) ||
!(myHashes[t] =
static_cast<size_t*>(calloc (s, sizeof *myHashes[t])))) {
for (; t < numTables; t++)
free (myHashers[t]), free (myHashes[t]);
goto failure;
}
}
/* Initialize the tables for the hash functions */
srand (time (0));
for (t = numTables; t--; )
for (s = funcSize; s--; )
myHashers[t][s] = size_t ((hashSize + double (1)) * rand () /
(RAND_MAX + double (1)));
myNumTables = numTables;
myFuncSize = funcSize - 1;
myHashSize = hashSize;
return true;
}
bool
HashGraph::do_add (const void* buf,
size_t size)
{
/** flag: was the state found? */
bool found = true;
/** the encoded byte stream */
const char* state = reinterpret_cast<const char*>(buf);
for (unsigned t = myNumTables; t--; ) {
/* compute the hash value */
size_t h = 0;
const size_t* hasher = myHashers[t];
for (size_t s = size; s--; )
h += state[s] * hasher[s & myFuncSize];
/* test and set the corresponding bit in the hash table */
h %= myHashSize;
size_t& ht = myHashes[t][h / SIZE_T_BIT];
size_t mask = size_t (1) << (h % SIZE_T_BIT);
if (!(ht & mask))
ht |= mask, found = false;
}
if (found)
return false;
newState ();
assert (myPathFileLength == ftell (myPathFile));
assert (!myOffset || myOffset < myPathFileLength);
mySearch.push (buf, size, myPathFileLength);
class BytePacker p;
p.append (myOffset), p.append (size);
fwrite (p.getBuf (), 1, p.getLength (), myPathFile);
fwrite (buf, 1, size, myPathFile);
myPathFileLength += p.getLength () + size;
return true;
}
word_t*
HashGraph::getState (long pos, size_t* size) const
{
unsigned char rbuf[8];
class ByteUnpacker u (rbuf);
assert (pos < myPathFileLength);
fseek (myPathFile, pos, SEEK_SET);
fread (rbuf, sizeof rbuf, 1, myPathFile);
unsigned offset = u.extract ();
unsigned len = u.extract (); u.buf = rbuf;
word_t* state = new word_t[len + (sizeof (word_t) - 1) / sizeof (word_t)];
fseek (myPathFile,
pos + BytePacker::size (offset) + BytePacker::size (len), SEEK_SET);
fread (state, 1, len, myPathFile);
*size = len;
return state;
}
word_t*
HashGraph::pop (bool tail, size_t& size)
{
if (mySearch.empty ())
return 0;
return mySearch.pop (tail, myOffset, &size);
}
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