Mail Archives: djgpp/1997/01/27/02:11:07
On Wed, 22 Jan 1997, Matthew Kennedy wrote:
> I haven't has much success in finding documentation on these variables -
> used so frequently in the sample ISR programs (like mkkbd3 etc).
__djgpp_base_address is documented with the `__djgpp_nearptr_enable'
library function on the libc.inf library reference docs file. I don't
know what __djgpp_dos_sel is; if you mean _dos_ds, then it is documented
with the `_go32_info_block' variable on libc.inf. __djgpp_ds_alias is a
selector that has the same base address and limit as the one loaded into
DS register, but it is always valid, while DS is sometimes made
deliberately invalid by the DJGPP signal support (so acessing a memory
will cause an exception and call the signal handler), and so if you use
DS from a hardware interrupt handler, it might crash when you press e.g.
Ctrl-Break (which causes a SIGINT).
Generally, searching for these in the libc.inf file should find you all
the references to them. Fire up info.exe and press `s' to search the
entire reference.
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