Messages in this thread | | | From | <> | Subject | Q: console_macros.h | Date | Wed, 8 Jun 2005 12:49:22 -0400 |
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#define vc_state ....
This particular macro happens to be the SAME NAME as the vconsole data structure member it references.
This seems quite unhandy if you try to reference the vc_state member using a pointer to a vconsole data structure like so:
struct vc_data *vcdp = vc_cons[currcons].d;
vcdp->vc_state = whatever...;
The macro will expand (because of course it has the same name and the preprocessor doesn't know the difference) when what you really wanted was the structure member. Cryptic syntax errors result.
So... HERE IS THE QUESTION: was there some compelling reason this particular macro should be this way, (rather than #define state ...) or was it just some ages old typo that was never noticed?
Of course, if all you use is the macros to reference vconsole data, the issue never surfaces - but the resultant code quality suffers when some function has several macros in it that could benefit from caching a pointer to the current vcon structure and using that.
Caching console data pointers rather than using the macros everywhere in a prototype I've been working up has provided a fairly dramatic reduction in the amount of code and it will run a lot faster as well with fewer indirections to follow. With the macros, on an x86 build I was seeing sequences of several LEA instructions all over the place for the multiple indirections.
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