PC Extra Super CD 1998 January/PCPLUS131.iso/DJGPP/V2/DJLSR201.ZIP/src/libc/go32/gopvec.txh

Text File | 1995-12-23 | 2.4 KB | 107 lines

@node _go32_dpmi_get_protected_mode_interrupt_vector, dpmi
@subheading Syntax

@example
#include <dpmi.h>

int _go32_dpmi_get_protected_mode_interrupt_vector(int vector, _go32_dpmi_seginfo *info);
@end example

@subheading Description

@xref{DPMI Overview}

This function puts the selector and offset of the specified interrupt
vector into the @code{pm_selector} and @code{pm_offset} fields of
@var{info}.  This structure can be saved and later passed to
@code{_go32_dpmi_get_protected_mode_interrupt_vector} to restore
a vector.

@subheading Return Value

Zero on success, nonzero on failure.

@subheading Example

@xref{_go32_dpmi_set_protected_mode_interrupt_vector}

@c ----------------------------------------------------------------------
@node _go32_dpmi_set_protected_mode_interrupt_vector, dpmi
@subheading Syntax

@example
#include <dpmi.h>

int _go32_dpmi_set_protected_mode_interrupt_vector(int vector, _go32_dpmi_seginfo *info);
@end example

@subheading Description

@xref{DPMI Overview}

This function sets the protected mode interrupt vector specified to
point to the given function.  The @code{pm_offset} and
@code{pm_selector} fields of @var{info} must be filled in
(@pxref{_go32_my_cs}).  The following should be noted:

@itemize @bullet

@item

You may not @code{longjmp} out of an interrupt handler.

@item

You may not make any function calls that require system calls, such
as @code{printf}.

@item

This function will not wrap the handler for you.  The
@code{_go32_dpmi_allocate_iret_wrapper} and
@code{_go32_dpmi_chain_protected_mode_interrupt_vector} functions can
wrap your function if you want.

@item

You must set the pm_selector field of @var{info}.  Use
@code{_go32_my_cs} to get a selector valid for your functions.

@end itemize

@subheading Return Value

Zero on success, nonzero on failure.

@subheading Example

@example
volatile int tics = 0;

timer_handler()
@{
  tics++;
@}

int main()
@{
  _go32_dpmi_seginfo old_handler, new_handler;

  printf("grabbing timer interrupt\n");
  _go32_dpmi_get_protected_mode_interrupt_vector(8, &old_handler);

  new_handler.pm_offset = (int)tic_handler;
  new_handler.pm_selector = _go32_my_cs();
  _go32_dpmi_chain_protected_mode_interrupt_vector(8, &new_handler);

  getkey();

  printf("releasing timer interrupt\n");
  _go32_dpmi_set_protected_mode_interrupt_vector(8, &old_handler);

  return 0;
@}

@end example