Subclassing Application Class

Grzegorz Kraszewski

Introduction

Every MUI application is (or at least should be) an event driven one. It means the application provides a set of actions, which may be triggered with user activity (like using mouse and keyboard). The straightforward way of implementing this set of actions is to implement it as a set of metods added to some MUI object. For simple programs, the best candidate for adding such methods is the master Application object. More complex programs (for example ones using multi-document interface) may add actions to other classes, for example Window one.

Why methods? Implementing actions as methods has many advantages:

• Methods may be used directly as notification actions. It saves a programmer from using hook tricks or cluttering the main loop with teens of ReturnID values.
• Methods may be coupled directly with scripting language interface (formerly known as ARexx interface) commands.
• Methods used in notifications are executed immediately in response of user actions. No delay is introduced by the main loop (especially if it is not empty).
• A notification triggering attribute value may be passed directly to method, as its parameter.
• Using methods improves code modularity.

The Application

Many programming tutorials tend to bore readers with some useless examples. In this one a "real world" application will be ported to MorphOS and "MUI-fied". The application is SciMark 2. SciMark is an another CPU/memory benchmark. It performs some typical scientific calculations like Fast Fourier Transform, matrix LU decomposition, sparse matrix multiplication and so on. The benchmark measures mainly CPU speed at floating point calculations, cache efficiency and memory speed. Being written in Java initially, it has been rewritten in C (and in fact in many other languages). The C source is available on the project homepage.

The source uses only pure ANSI C standard, so it is easily compilable on MorphOS using provided Makefile. One has just replace $CC = cc line to $CC = gcc, to match the name of the MorphOS compiler. As a result, a typical shell-based application is obtained. Here are example results for a Pegasos 2 machine with G4 processor:

Not very impressive in fact. This is because no optimizaton flags are passed to the compiler in the makefile. They can be added by inserting a line $CFLAGS = -O3 below the $CC = gcc one. Let's also link with libnix (a statically linked unix environment emulation, see Standard C and C++ Libraries) by adding -noixemul to CFLAGS and LDFLAGS. After rebuilding the program and running it again the results are significantly improved (the program has been compiled with GCC 4.4.4 from the official SDK).

This shows how important is optimization of the code, especially computationally intensive one. Optimized code is more than 4 times faster!