From: mpenacho AT tezcat DOT com (Mark Penacho)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Hooking interrupts
Date: Sat, 18 Jan 97 07:39:12 GMT
Organization: Tezcat.COM  - Specialists in human interconnectivity.
Lines: 78
Message-ID: <5bpun2$gv0@tepe.tezcat.com>
References: <32E045B5 DOT 4680 AT mail DOT idt DOT net> <5bples$dql AT tepe DOT tezcat DOT com>
NNTP-Posting-Host: mpenacho.tezcat.com
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

In article <5bples$dql AT tepe DOT tezcat DOT com>, mpenacho AT tezcat DOT com (Mark Penacho) wrote:
>In article <32E045B5 DOT 4680 AT mail DOT idt DOT net>, Joseph Turian <turian AT mail DOT idt DOT net>
> wrote:
>>Is it possible to hook an interrupt while in protected mode? I wanted
>>to write a keyboard handler, but I am new to djgpp and only know how
>>it is done in 8086 assembly

sorry about the incomplete last posting

typedef unsigned long ADDRESS;
#define KEYBOARD_INT    0x09;


>#include <go32.h>
>#include <dpmi.h>
>
>_go32_dpmi_seginfo   old_keyboard_isr;
>_go32_dpmi_seginfo   keyboard_interrupt_holder;
>int raw_scan_code;
>
>void init_keyboard(void) {
>   while(kbhit())
>      getch();
>
>   _go32_dpmi_lock_code(keyboard_irq, (ADDRESS)end_keyboard_irq  -  \
>        (ADDRESS)_keyboard_irq);
>   _go32_dpmi_lock_code(key_asm, 30);
>   _go32_dpmi_lock_data(&raw_scan_code,sizeof(raw_scan_code));
>   _go32_dpmi_lock_data  (ALL OTHER KEYBOARD IRQ VARIABLES)
>
>   _go32_dpmi_get_protected_mode_interrupt_vector(KEYBOARD_INT,  \
>        &old_keyboard_isr)
>   keyboard_interrupt_holder.pm_offset = (ADDRESS)keyboard_irq;
>   _go32_dpmi_allocate_iret_wrapper(&keyboard_interrupt_holder);
>   _go32_dpmi_set_protected_mode_interrupt_vector(KEYBOARD_INT,  \
>        &keyboard_interrupt_holder);
>}
>
>void uninit_keyboard() {
>    _go32_dpmi_set_protected_mode_interrupt_vector(KEYBOARD_INT, \
>        &old_keyboard_isr);
>   _go32_dpmi_free_iret_wrapper(&keyboard_interrupt_holder);
>}
>
>void keyboard_irq(void) {
>   key_asm();
>   DO SOMETHING WITH raw_scan_code;
>}
>
>int end_keyboard_irq(void) {  // do something unique to guarantee \
>                                         //optimization doesn't overrride
>   return(4);
>}
>
>
>assembly part (I use nasm, your code may vary)
>
>[BITS 32]
>[GLOBAL _key_asm]
>[EXTERN _raw_scan_code]
>[SECTION .text]
>
>_key_asm:
>        sti
>        xor     eax,eax
>        in      al,60h
>        mov     dword [_raw_scan_code],eax
>        in      al,61h
>        or      al,82h
>        out     61h,al
>        and     al,7fh
>        out     61h,al
>        mov     al,20h
>        out     20h,al
>        ret
>
>
>