Process Lasso CODEC Plug-ins

Overview:

A CODEC plug-in is created as a CODEC Host Module. This is simply the DLL that exposes any number of CODEC(s) to PECompact2. Users of PECompact2 may select any number of Codec Host Module DLL(s) they wish to use to encode their modules. Each CODEC Host Module (CODEC plug-in) may internally contain any number of encoding and decoding functions referenced by index. These are not selectable by the user, only the CODEC Host Module itself is selectable by the user. When the CODEC Host Module is chosen, all the CODEC(s) included in it are invoked in order. In summary, the user may select any number of CODEC Host Modules, each of which may contain any number of actual CODECs.

Example:

The following CODEC Host Module would invoke a CRC32 algorithm, the FFCE compression algorithm, then another CRC32 algorithm. The user would simply select 'pec2codec_ffce_with_crc32.dll', not seeing that there are actually three CODECs within the Host Module.

*The above configuration isn't optimal since two CRC32 checks will be fairly slow. It is for demonstrative purposes only.

The CODECs contained within a CODEC Host Module are identified by a zero based index number. Each CODEC exposes a number of entry points (APIs) listed in the CODEC Functions topic. To retrieve these entry-points, a call is made to the host module API CodecGetProcAddress, passing the the index of the desired codec and the name of the API to retrieve the address of.

Ordering (CODEC indices) is very important. Codecs are invoked during encoding in ascending order, starting with index 0. During decoding, the inverse order is used.

Sample code:

Your PECompact installation includes source codes for a CODEC template (C++/asm) and a CODEC that converts code endianness of code (C++ only).

A CODEC Host Module exposes these APIs:

FARPROC WINAPI CodecGetProcAddress(DWORD dwIndex, LPCSTR pszApiName);
DWORD WINAPI GetNumberOfCodecs();