jump to label under gcc

biffle · 06-09-2007, 09:57 PM

gcc extends c to permit a computed goto. Supposedly you can jump to the address codeaddress a labelled code section

codelabel: (some code)

by declaring

void * codeaddress

and assigning

codeaddress = &&codelabel

This is used to write threaded-code interpreters or compilers, e.g. for SMALLTALK, but I cannot make the code in the references under "threaded code" on the Web work.

Does anyone have experience with this?

Thanks

traene · 06-10-2007, 02:26 PM

Hi, sorry i don't get quite what you're going to do. Do you want to jump to different places, depending on some state? I think what will work is somthing like:

Code:

int i=0;
label:
++i
if (i<3) goto label;

I you do want to write a parser / interpreter for some kind of programming language you may have look at the yacc / bison tools.

biffle · 07-02-2007, 11:19 PM

Quote:

Originally Posted by traene

Hi, sorry i don't get quite what you're going to do. Do you want to jump to different places, depending on some state? I think what will work is somthing like:

Code:

int i=0;
label:
++i
if (i<3) goto label;

I you do want to write a parser / interpreter for some kind of programming language you may have look at the yacc / bison tools.

- THANKS, WILL LOOK AT bISON. What I want to do is to create a compiler that generates a pointer array COMPILE[n] containing successive lavel addresses &&labeladdress. I succeeded in dong that, but the addresses are wrong. Maybe this works only for simple interpreters.

thanks again, Biffle