*
* trap_a.asm - Example trap handling code (leaves D0 intact)

* Copyright (c) 1990 Commodore-Amiga, Inc.
*
* This example is provided in electronic form by Commodore-Amiga, Inc. for
* use with the 1.3 revisions of the Addison-Wesley Amiga reference manuals. 
* The 1.3 Addison-Wesley Amiga Reference Manual series contains additional
* information on the correct usage of the techniques and operating system
* functions presented in this example.  The source and executable code of
* this example may only be distributed in free electronic form, via bulletin
* board or as part of a fully non-commercial and freely redistributable
* diskette.  Both the source and executable code (including comments) must
* be included, without modification, in any copy.  This example may not be
* published in printed form or distributed with any commercial product.
* However, the programming techniques and support routines set forth in
* this example may be used in the development of original executable
* software products for Commodore Amiga computers.
* All other rights reserved.
* This example is provided "as-is" and is subject to change; no warranties
* are made.  All use is at your own risk.  No liability or responsibility
* is assumed.
*
* Entered in supervisor mode with the following on the supervisor stack:
*    0(sp).l = trap#
*    4(sp) Processor dependent exception frame

    INCLUDE "exec/types.i"
    INCLUDE "libraries/dos.i"


	XDEF _trapa

        XREF _countdiv0
        XREF _oldTrapCode

	section code

_trapa:                                 ; our trap handler entry
        CMPI.L	#5,(SP)                 ; is this a divide by zero ?
        BNE.S   notdiv0                 ; no
        ADD.L   #1,_countdiv0           ; yes, increment our div0 count
endtrap:
        ADDQ	#4,SP                   ; remove exception number from SSP
        RTE                             ; return from exception

notdiv0:
        TST.L   _oldTrapCode            ; is there another trap handler ?
        BEQ.S	endtrap                 ; no, so we'll exit
        MOVE.L  _oldTrapCode,-(SP)      ; yes, go on to old TrapCode
        RTS                             ; jumps to old TrapCode

        END