Re: [Amforth-devel] HOW TO - Assembler in anmforth

[Matthias T. <mt...@we...>]

Pito,

I'll start here, the upper "half" will take more time.
But make yourself clear, what do you want to achieve:
add an assembly word to the initial hex file or implement
it on a running system. The assemblers only look similiar,
they are not inter-changeable.

> Interrupts:

The interrupt support in amforth is weak. It lakes some
features one may urgently need.

> 1. it is understood you handle intrpts forth's way - the
> generic-isr.asm is an interface to forth only, which sets Tflag and
> translates vector to forth. What is the worst case latency?

1ms (if the interrupt occures at the beginning of the word 1ms.)
I believe, that division is faster, but did not test it yet. Generally
speaking: interrupts are handled by the inner interpreter. Any
primitive word is atomar wrt to (forth-level) interrupts.

> 2. how to work with several interrupts enabled (priority handling in
> forth?), e.g. as we register ['] tick_isr TIMER2_OVFAddr int!, what
> happens when I register for example 15 interrupts sources that way?

The last registered code gets called. A problem arises, if interrupt
x has fired and interrupt y comes before the x has been handled. In
that case x will be completly unhandled (the curint variable is
overwritten).

Matthias