Mail Archives: djgpp/1996/06/10/11:07:25
On Mon, 10 Jun 1996, Shawn Hargreaves wrote:
> How does libc handle it?
You mean to say that you do serious work with DJGPP without libc sources
installed ;-) ?
> It must define it somewhere (at least I assume
> so, because there is no linker error if a program doesn't provide it) but
> it can be overridden at will. I have a feeling that might be because libc
> defines it to be zero, but in that case my definition in Allegro ought to
> work the same because I'm currently just zeroing it to force the non-move
> sbrk() algorithm...
If you are willing to trust the library to never change the default
setting, you don't need to set the bit yourself. But if you want to be
*sure* that the non-moving sbrk will be used, there is no other way than
to set the bit to whatever you need.
This particular bit (unlike some other bits) is tested by `sbrk' every
time it allocates another chunk of memory (look in src/libc/crt0/crt0.s in
the library sources), which explains why you can change the behavior at
runtime.
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