Available No. of Registers

[marty]

Some more insights on coding style using register variables for
effiency.

I've done a lot of real-time coding with Manx Aztec C for 8085 machines.
Manx allows one register variable (stored in the BC pair).

When the code can be non-reentrant, I've found it effective to pick one
good variable (often a pointer to structure) to be register and the rest
static.  Stack operations are expensive on 8080 architectures and
real-time performance is important.

Any additional register declarations beyond the first Manx treats as
auto (which means stack, which is undesirable).  There is a compile time
option to convert autos to statics.  

I've usually been pretty happy with the assembly language this compiler
generates.  I feel if at all possible it is better to stay away from
assembly language for any meaningful algorithms.  Significant
optimization can be performed on small machines by "fiddling" with the C
source and understanding the compiler output.  Of course, oddball
implementations with the idea the intent of increased speed should
thoroughly commented.

marty
leisner.henr at xerox.com