Next: , Previous: Library bases, Up: Top


10 Writing small programs

Writing very small programs is a trivial thing - if you know how to do it. Here are some basic tips and tricks:

Do not use printf:
printf’ is the most high-level function of usual ANSI C libraries and builds on almost everything else. Often this function can be replaced by simpler routines like e.g. ‘puts’. The same is true for the other formatted I/O functions.

If you write amiga-only programs you can use the ‘sprintf’ routine of libamiga.a by linking with ‘-lamiga’.

Try to avoid using buffered I/O:
A lot of programs can be written using the low-level I/O-functions ‘read’ and ‘write’. This saves the code responsible for buffered I/O.
Avoid -O3:
-O3’ activates all those optimizations that sacrifice code size for speed. An exception is ‘-fstrength-reduce’ which costs compile time but not code size. ‘-O2 -fstrength-reduce’ will give small programs.
Strip your executables:
gcc doesn't strip executables by default. Setting ‘-s’ will give worse debugable but small programs.
Use small code and data model:
-msmall-code -fbaserel’ do this. Be aware that this won't work for larger programs.
Don't use libgcc.a:
libgcc.a’ which calls global C++ constructors and destructors builds on ‘atexit’ which builds on ‘malloc’, ... If your program doesn't use them you can save some memory by linking by hand (‘-nostdlib’).
Set __nocommandline:
If you use ‘ReadArgs’ instead of ‘argc, argv’ you can save some memory by setting a global variable named ‘__nocommandline’ to drop parsing of commandline arguments.