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README
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README
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GETTING STARTED:
The script 'example1.py' shows how to create a BDD manager, various BDD variables
and how to find the truth set of a small function. Look at the comments and code in
this script to see how it is done. This script is executable from the command line.
Alternativley, Python may be started and individual commands may be entered at the
Python prompt.
Refer to the excellent documentation in the doc directory of the CUDD distribution for
details on CUDD functions. The various .i files show what CUDD functions are available
in PyCUDD. For example, from ddmanager.i:
DdNode * zddIthVar( int i) { DdNode* result = Cudd_zddIthVar(self, i); Cudd_Ref(result); return result; }
indicates that the CUDD function 'Cudd_zddIthVar' is available as the DdManager method
'zddIthVar' in Python. It would be called as:
x = mgr.zddIthVar(i)
from Python. x is a returned Python DdNode object, mgr is an existing Python DdManager object, i is an integer.
As a general rule, drop the 'Cudd' or 'Cudd_bdd' from the prefix of the CUDD function to
arrive at the Python method. If a CUDD function requires a DdNode argument, it will
typically be a method of the Python DdNode class. The first DdNode in the argument list is
the 'self' or 'this' pointer. For example,
DdNode* Cudd_bddAndAbstract(DdManager *manager, DdNode *f, DdNode *g, DdNode *cube)
is callable from python as
x = f.AndAbstract(g,cube)
ZBDDs and ADDs are available in PyCUDD as well. The CUDD package treats a BDD,
ZBDD or ADD as a DdNode. For ease of implementation, this version of PyCUDD also
has only one DdNode object. This means that many methods are unprotected. If you
call a method that expects BDDs but you pass ZBDDs, then pycudd will probably
crash. This also means that operator overloading applies only to BDDs.
(See pycudd.i for operator overloading details.) For example, if you want the union
of two ZBDDs, you must use
x = y.zddUnion(z)
where y and z are Python DdNode objects and x is a returned Python DdNode object.
In this case, all DdNode objects are ZBDDs. Calling
x = y + z
where y and z are ZBDD Python DdNode objects will crash as the + operator is
overloaded only for DdNode objects which are BDDs. Future versions of PyCUDD will
deal with this situation in a better way.
CUDD sometimes requires arguments or returns values that are DdNode, int or double
arrays. Use the helper objects DdArray, IntArray or DoubleArray when this is required.
For example, the CUDD function
int Cudd_SetVarMap(DdManager *manager, DdNode **x, DdNode **y, int n)
is called from Python as
mgr.SetVarMap(x,y,n)
where x and y are existing DdArray objects and n is an integer. Refer
to the .i files and pycudd.cpp to see how helper objects are created.
The CUDD package has been extended in pycudd. Extended features are indicated in
the .i files by the comments 'Added to DdManager' and 'Added to DdNode'. The helper
class DdArray also has some extended features. For example, given a DdArray object ddarray,
f = ddarray.Constraint(low, high)
will return a DdNode object f where terms of f are all possible combinations of
subterms in the DdArray. All terms in f will contain no less than low and no more than
high subterms from the DdArray.
USING BREL (beta)
The BREL interface is still in testing -- it currently has just the basic functionality.
Refer to example3.py for usage.
PyCUDD is distributed with the BSD V.3 license below. CUDD is distributed and maintained by the University of Colorado, under its own license, no claims or guarantees are made for the use of CUDD.
Copyright (c) 2014, The Regents of the University of California
All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.