From:	CRDGW2::CRDGW2::MRGATE::"SMTP::CRVAX.SRI.COM::RELAY-INFO-VAX"  7-DEC-1989 03:26
To:	MRGATE::"ARISIA::EVERHART"
Subj:	$SETIMR, ASTs and 16(AP)

Message-Id:  <8912070825.AA13786@crdgw1.ge.com>
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Date:     Wed, 6 Dec 89 13:51 MST
From: <ACM%NAUVAX.BITNET@CUNYVM.CUNY.EDU> (Anthony C. McCracken)
Subject:  $SETIMR, ASTs and 16(AP)
To: INFO-VAX@SRI.COM
X-Original-To:  INFO-VAX@SRI.COM, ACM

   Someone wrote earlier that while in an AST routine, the VMS documentation
says that 16(AP) holds the address that the MAIN program was at when the
AST interupt was called. I tried a small test and sure enough, the VMS
documentation is CORRECT. Transcript follows.


$ CREATE FOO.MAR
        .TITLE  FOO
        .IDENT  /V1.0/
        .PSECT  VDATA,RD,WRT,NOEXE

DELAY:  .LONG   1000*100*100*5 * -1     ; EXACTLY 5 SECS.
        .LONG   -1

        .PSECT CODE,RD,NOWRT,EXE
        .ENTRY  MAIN,^M<>
        $SETIMR_S       DAYTIM=DELAY,ASTADR=TIMEAST
LOOP:   MOVL    R8,R9           ; here is a
LOOP1:  MOVL    R10,R8          ; real dumb
LOOP2:  MOVL    R9,R10          ; do nothing loop
LOOP3:  BRB     LOOP            ; while waiting for the AST
        RET
TIMEAST:
        .WORD   ^X07FC          ; entry mask, the hard way
BK:     MOVL    #1,R0
        $EXIT_S R0
        RET
        .END    MAIN
^Z
$ MACRO/DEBUG FOO
$ LINK/DEBUG FOO
$ RUN FOO

         VAX DEBUG Version V5.0-00 MP
%DEBUG-I-INITIAL, language is MACRO, module set to FOO

DBG> SET BREAK BK
DBG> GO
break at FOO\TIMEAST\BK
    18: BK:     MOVL    #1,R0

DBG> EXAMINE @AP+10
7FF2177C:       0000041F

DBG> SYMBOLIZE 41F
address 0000041F:
    FOO\MAIN\LOOP2
    FOO\MAIN\%LINE 13
address 0000041F: (global)
    MAIN+1F
DBG> EXIT

Looks like my little program was interupted at LOOP2:   MOVL    R9,R10
according to the address/value at AP+10.
In MACRO, the debuggers default radix is hex. 10hex = 16decimal


**************************************************************************
Disclaimer: There can't be a problem,   | Anthony C. McCracken
            it works fine for me !!     | Northern Arizona University
                                        | ACM@NAUVAX.BitNet
**************************************************************************