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Node:_go32 vs __dpmi,
Next:HW Int pitfalls,
Q: In v1.x I was used to the
_go32_... functions, but
now comes v2 which also has
__dpmi_... functions. Are there
any differences between these two varieties?
Q: Do I need to convert my old v1.x code to use the new
A: These two groups of functions have different functionality, so
don't just substitute the new ones for the older ones, because it
usually won't work! The new
__dpmi_... functions are just
bare-bones wrappers of the DPMI API calls36 (see DPMI Specification), generally unsuitable for use with
handlers written in C, whereas the old
are intelligent helper routines which only make sense if your interrupt
handlers are C functions. They save all the registers on the stack (to
be restored before return to caller), and set up DS, SS, and
ES registers as GCC assumes in the code it produces for a C
program. If these assumptions are wrong, the C functions called by an
interrupt handler will crash miserably.
The problem with the
_go32_... functions is that they don't
lock all the code and data that your handlers use, so they can crash on
memory-tight machines and thus aren't suitable for production-quality
code. But they are certainly useful in the initial stages of writing
and debugging code that hooks hardware interrupts, and for migrating
existing v1.x code to v2. Some of the old names were just
#defined to the new names where the functionality is identical.
The bottom line is that it shouldn't be necessary to convert your code
for it to work at least as well as it did in v1.x; but if you want it to
be more stable, you should rewrite your handlers in assembly and use the
__dpmi_... functions. See How to install a hardware interrupt handler.