Re: ISA and copyright/patent/trademark

On Wed, 15 Apr 2009 18:57:01 -0400, CBFalconer wrote:

zwsdotcom@xxxxxxxxx wrote:
rickman <gnu...@xxxxxxxxx> wrote:

As to the ISA, it seems clear by example that the instruction set is
not copyrightable, only the opcode names. As to patents, I

ARM and Microchip have pursued people implementing architecture- clones
quite aggressively. Of course, why anyone would want to copy the PIC is
an unholy mystery.

Actually, if you stick to assembly code, they are quite useful. Just
don't try to use anything approaching a higher level language. Maybe
Forth works.

I've got a project using a 32K device that has over 8000 lines of 'c' and
about 1000 lines of asm. I use the free compiler from Microchip.
Even without the optimizing compiler I have some room left over. There
are some rules to follow with the c compiler
like:
if (a) return 1 else return 2

instead of
if (a) r = 1 else r = 2;
return r;

Also use bit fields any time you can. Switch statements can be better
than if/else if/else. Compound logical expressions in if statements
can produce some nasty code. If you look at the assembly listing and
play with some code constructs you can many times find a better way to
code for the compiler.

--
Joe Chisolm
Marble Falls, TX
.

Relevant Pages

  • Re: What micros do you actually like to work with?
    ... I really like ARM chips. ... I also like the 68K architecture which IMHO ... The MSP430 on the other hand has a GNU compiler collection compiler ... makes for easy and readable assembly code. ...
    (comp.arch.embedded)
  • Re: Poor performance of implied-DO loop with Intel Fortran
    ... Obviously v8.0 of the Intel compiler scales fine, ... makes me think I will continue to use this idiom with an eye to any ... > way to fill large arrays. ... > the generated assembly code, ...
    (comp.lang.fortran)
  • Re: Assembling Visual Studio generated listing files
    ... assembly code) internally. ... the Bliss-11 compiler we did at CMU (because there were so many PDP-11 object ... on all machines) and the original PDP-11 C compiler from Bell Labs. ... Not just a little bit stupid; ...
    (microsoft.public.vc.mfc)
  • Re: PIC Assembler.
    ... MPLAB easier to get started, or would I seriously disadvantage ... Microchip makes a C compiler available on a 90-day trial basis. ...
    (sci.electronics.basics)
  • Re: Question about function call in a microprocessor?
    ... > or subroutine call in a assembly code. ... > about the stack here. ... > foo uses lets says 5 local varaibles. ... compiler and look at the output listing. ...
    (sci.electronics.design)
Loading