RXTX is a native lib providing serial and parallel communication for the Java Development Toolkit (JDK). All deliverables are under the gnu LGPL license. The native part is developed in C.

If you are using the parallel port functions of this project for version rxtx-2.1-7r2 or older, you may be interested in this code optimization, it is a small change but it may improve the resource usage in certain cases.

Let’s take a look to readArray function in ParallelImp.c, this is a summary of the current implementation:

buffer = (unsigned char *)malloc( sizeof( unsigned char ) * length );
bytes = read_byte_array( fd, buffer, length, threshold, timeout );
for( i = 0; i < bytes; i++ ) body[ i + offset ] = buffer[ i ];
free( buffer );

In C we can increment the output buffer pointer to the position we want to start to write (offset) directly, avoiding the necessity of allocating a new buffer and copying the contents, for example:

//buffer = (unsigned char *)malloc( sizeof( unsigned char ) * length );
buffer = body+offset
bytes = read_byte_array( fd, buffer, length, threshold, timeout );
//for( i = 0; i < bytes; i++ ) body[ i + offset ] = buffer[ i ];
//free( buffer );

This kind optimization can be also applied to the writeArray function in the same source file.

I’m going to send this information to the RXTX project mailing list, hopefully it will be available in next version!

picture source

This script is similar to my previous post Sln2Make but instead of generating Makefiles it creates SCons scripts. The class Sln2SCons does all the work, parses the sln and vcproj files and generates a main SConstruct and one SConscript for every project in the solution. To use it, just instantiate the class with the following parameters:

Sln2SCons(slnpath, exlist, dirrepl, librepl, outdir)

where:

• slnpath is the path to the solution file
• exlist an optional list of files to exclude, optionally you can pass an alternative script name to be included from the main SConstruct: [[script_to_exclude, alt_script], …]
• dirrepl a list of directory replacement rules
• librepl library name replacement rules (when win library name doesn’t match OS’s library name)
• outdir is the output directory for the SConstruct

example:

# custom scripts
exlist = [('../extsrc/apr/SConscript', 'extsrc/apr/SConscript.py')]
# special directory replacement rules
dirrepl = []
# special library name replacement rules (when win library name doesn't match OS's library name)
librepl = []
Sln2SCons("../winnt/test.sln", exlist, dirrepl, librepl, "../")

To correct the path case, I’ve used a script published by Moshe Zadka here.
Use this code at your own risk, it is released under BSD license.

The source is in Google Code now, here is the link.