Syntax of auto declarations

[slorquet]

Hello,

After having some discussion about the B language with unix experts on the TUHS mailing list it appears that the constant values in auto declarations are not initial values but vector dimensions.

The reference for this is Ken Thompson's language specification here:

https://www.bell-labs.com/usr/dmr/www/kbman.html

Later on, the B language was ported to the H6070 computer, and the spec was evolved to include brackets as described in this document, while changing the meaning of the constant to an unusual one :

https://www.bell-labs.com/usr/dmr/www/bref.pdf

So in your fibonacci example, the initial values of variables should be defined by assignment expressions at the beginning of the code. The syntax you have used here:

auto a, b 1, c, i 0;

is in fact incorrect and means in normal C:

int a, b[1], c, i[0];

which makes no sense, but the actual required syntax is:

auto a, b, c, i;
b=1;
i=0;

Best regards

[Spydr06]

Thank you! This wasn't quite clear to me from the kbman alone, I'll definitely fix it in the compiler

Just out of curiosity, has this compiler been useful for you? You seem to be somewhat connected in that area.

[Spydr06]

Commit da85e36 implements the auto a [N]; syntax and fixes auto a N; to behave correctly.
There are still some issues with the stack offset though, will fix that soon!

[slorquet]

Hi,
I did a review of other compiler projects to find code examples to test my compiler on.
So I had a look at your compiler, which confimed that a recursive descent parser was the right way to go, but I avoided looking at it in too many details, not to be influenced by it :)

My own compiler (not on github) has a goal of generating code for retro 8-bit targets. Apart that it has nothing special. Recursive descent written in C.

[Spydr06]

Oh nice, sounds like a fun project!

[Spydr06]

Stack alignment issues (hopefully) fixed with adf8d94