Re: [Amforth] Compiling Amforth 4.9 - forward labels in macros

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

Hi,

> Generated jump goes one word too far (it is "jump 5 words forward"
> and not "jump 4 words forward"). It can even be seen
> that the length of a macro expansion is wrongly estimated
> (it says the whole code is 7 words, while it is only 6).
> 
> avrasm2 generally does not allow using not-yet-defind
> labels in macros like this.

really? I doubt it.

> 
> So there are two workarounds for amforth:
> 
> 1) revert to amforth 4.4 hardcoded "rjmp" since we can
>    assume the distance is pretty small here.
> 
> 2) add a nop after "rjmp" in the "jmp_" macro to keep
>    sizes of the macro expansion constant.

That would contradict one of the 2 intentions of
the macro: size savings (the other one is speed).

> 
> 
> Solutions:
> 
> 1) AVRA may disallow forward refences in the macros.
> 
> 2) Detecting the impossibility to determine
>    the value.
> 
> 3) ...

3) get an smart jump instruction.

I vote for 3) ;)

Does the patch

diff --git a/core/dict_core.inc b/core/dict_core.inc
index b7ddeb1..d88f9f6 100644
--- a/core/dict_core.inc
+++ b/core/dict_core.inc
@@ -74,8 +74,8 @@
 .include "words/dodo.asm"
 .include "words/doqdo.asm"
 .include "words/i.asm"
-.include "words/doloop.asm"
 .include "words/doplusloop.asm"
+.include "words/doloop.asm"
 .include "words/unloop.asm"


help? Does the quick fix from workaround
1) give a working system?


Matthias