Patcher.pm is a perl module that simplifies creation of binary patches for executables. Individual patches are specified in config-like .pl files as binary, assembly or C code, the patcher takes care of compiling, linking and storing them inside the target executable. It should work on any recent Linux system and bin/patcher.exe is a Windows version made with perl packer. It is primarily targeted at older DOS executables where you may not have an option of using dynamic library and have to fit the patch into original file.
This program is free software, you can redistribute and/or modify it under the terms of GPLv3 license. It directly includes parts of GCC, as binaries shipped with MinGW and Strawberry Perl projects. The source code for those projects can be found on their respective websites.
Written by Alexey Svirchevsky.