_DEBUGGING REAL-TIME SYSTEMS_
by Joseph Newcomer

[LISTING ONE]

if debug_events
evlen=256
        public _event_len
        public _event_ptr
        public _event_last
        public _event_events
_event_len      dw      evlen
_event_ptr      dw      0
_event_last     db      0
_event_events   db      evlen dup(0)
endif

newevent        macro   ev
                local   L1
if debug_events
                inc     _event_ptr
                cmp     _event_ptr,evlen
                jl      L1
                mov     _event_ptr,0
L1:             push    bx
                  mov   bx,_event_ptr
                  mov   _event_events[bx],ev
                  mov   _event_events[bx+1],0
                  mov   _event_last,ev
                pop     bx
endif
                endm


[LISTING TWO]

        PUBLIC _cdiv
_cdiv   dw     0
cval    dw     0

_clock  proc far  ; interrupt entry point
        ...       ; interrupt prolog and setup
        dec  cval ; decrement divisor
        jle  ok   ; take interrupt
        jmp  cexit ; clock exit
ok:     mov  ax,_cdiv  ; set up for next time
        mov  cval,ax   ; ...
        ...       ; body of clock interrupt handler
cexit:  ...       ; epilog code
                  rti       ; return
                  endp


[LISTING THREE]



#pragma check_stack(off)
char bpts[50];
void bpt(int n)
    {
     if(bpts[n])
         _asm{
              mov ax,n;
              int 3;
             }

    }



[LISTING FOUR]


void show_bpts()
   {
    register char * where = bpts;
    _asm {
          mov ax,where;
          int 3;
         }
   }