Some updates to pcecd.c

[sukibaby]

pcecd.c: Define macros for CD control codes

This file is full of hard-coded control values without comments to describe what they do. This makes it very difficult to parse the code when read.

This commit introduces a macro to correspond to each control code used.

pcecd.c: Add some helper macros

Making macros to substitute a few frequently used commands. They perform important functions, and are called multiple times within the code, but the actual function has not been described in the code.

I felt a macro was the ideal way to handle this, since adding comments to each instance of these commands would increase clutter.

This will make the code easier to read, and also easier to maintain by reducing code duplication.

[rofl0r]

thanks. are you familiar enough with git to reword the commit messages so they're aligned to 80 chars
length for terminal use? otherwise one has to scroll right for every line exceeding it...