_go32_dpmi_allocate_real_mode_callback_iret

Syntax

#include <dpmi.h> int _go32_dpmi_allocate_real_mode_callback_iret( _go32_dpmi_seginfo *info, _go32_dpmi_registers *regs );

Description

See section DPMI Overview.

This function allocates a "real-mode callback". Fill in the pm_offset field of info and call this function. It will fill in the rm_segment and rm_offset fields. Any time a real-mode program calls the real-mode address, your function gets called. The registers in effect will be stored in regs, which should be a global, and will be passed to your function. Any changes in regs will be reflected back into real mode. A wrapper will be added to your function to simulate the effects of an iret instruction, so this function is useful for trapping real-mode software interrupts (like 0x1b - Ctrl-Break hit).

Return Value

Zero on success, nonzero on failure.

Portability

ANSI/ISO C	No
POSIX	No

Example

_go32_dpmi_registers regs; my_handler(_go32_dpmi_registers *r) { r->d.eax = 4; } setup() { _go32_dpmi_seginfo info; _go32_dpmi_seginfo old_vector; _go32_dpmi_get_real_mode_interrupt_vector(0x84, &old_vector); info.pm_offset = my_handler; _go32_dpmi_allocate_real_mode_callback_iret(&info, &regs); _go32_dpmi_set_real_mode_interrupt_vector(0x84, &info); do_stuff(); _go32_dpmi_set_real_mode_interrupt_vector(0x84, &old_vector); _go32_dpmi_free_real_mode_callback(&info); }