[Coco] C Coding question

[Jeff Teunissen]

On Wed, Dec 25, 2024, 23:13 dlb via Coco <coco at maltedmedia.com> wrote:

> I'm disassembling a program and came across something that was
> interesting, to say the least.  Here's what I have:
>

[snip]

L0762()

{
>     /* Why did they do this ??  Wouldn't (D0035 < D0037 work? */
>     while ((D0035 >= D0037) == 0)
>     {
>         if ((L1fca() != 0) || (L2474(1) == -1))
>         {
>             break;
>         }
>     }
> }
>
> The comment in the code above states my question.  Wouldn't what my
> suggestion do the same?  I cannot understand why anyone would write
> code like that unless there's something I am missing.
>

Looks like the L2474() function is, or calls, a system call (which return
-1 for any error), and calls it with the path number 1 (the standard output
path)? Anytime I see a "cmpd #-1" in C code I start thinking system call.

As for the test, I can't think of any obvious reasons someone would write
"while (!(var1 >= var2))" rather than "while (var2 < var1)" except for
inverting the meaning of code emitted by a macro. So I would think there
was likely a macro like

#define STATE (var1 >= var2)

such that code like

while (!STATE) {
 ...
}

might make sense.

Looks like the function might be writing chunks of text somewhere, and 0x35
and 0x37 are pointers?