From: system@SendSpamHere.ORG
Sent: Friday, March 03, 2000 9:43 AM
To: Info-VAX@Mvb.Saic.Com
Subject: Re: UWSS ALPHA Arg list homing and read access

In article <004aa0e3.c0dc768b@usw-ex0109-069.remarq.com>, Richard  <maher_rjNOmaSPAM@hotmail.com.invalid> writes:
>Is everyone else really struggling with C  to do this?
>
>All I want to know is "Has everyone else stopped probing
>the arg list on Alpha?"
>
>In the test code below you can see the probe commented out.
>
>A pointer to  a  manual would be great. I couldn't find it.
>
>Cheers Richard Maher.
>
>;++
>; (c) Copyright Tier3 Software
>;--
>        .TITLE  Test Alpha User Written System Services
>
>        .LIBRARY "SYS$LIBRARY:LIB.MLB"
>
>        .MACRO
>DEFINE_SERVICE,NAME,NARG=0,MODE=EXEC,EACCVIO,?CHKCNT,?
                                      ^^^^^^^------------->  ?EACCVIO

>ENDMACRO
>
>        'MODE'_ROUTINE_COUNT='MODE'_ROUTINE_COUNT+1
>
>        .CALL_ENTRY     MAX_ARGS=NARG,          -
>                        HOME_ARGS=TRUE,         -
>                        LABEL=NAME
>
>        .SAVE_PSECT     LOCAL_BLOCK
>
>        .PSECT  'MODE'_LIST,LONG,WRT,NOEXE,PIC,CON
>
>        .ADDRESS        NAME
>
>        .RESTORE_PSECT
>
>        .IF NOT_EQUAL NARG
>
>;       IFNORD  #<<NARG*4>+4>,(AP),EACCVIO
>;       BRB     CHKCNT
>;EACCVIO:
>;       MOVZWL  #SS$_ABORT,R0
>;       RET
>;CHKCNT:
>        CMPB    (AP),#NARG
>        BGEQ    ENDMACRO
>        MOVZWL  #SS$_INSFARG,R0
>        RET
>
>ENDMACRO:
>        .ENDC
>        .ENDM
>
>        $PLVDEF
>        $SSDEF
>
>KERNEL_ROUTINE_COUNT=0
>EXEC_ROUTINE_COUNT=0
>
>        .PSECT  EXEC_LIST,LONG,WRT,NOEXE,PIC,CON
>EXEC_TABLE:
>
>        .PSECT  KERNEL_LIST,LONG,WRT,NOEXE,PIC,CON
>KERNEL_TABLE:
>
>        .PSECT  USER_CODE,BYTE,NOWRT,EXE,PIC
>
>        DEFINE_SERVICE USER_GET_TODR,1
>
>        MOVL    4(AP),R5                ; Get address to
>store time of day
>register
>        IFNOWRT #4,(R5),10$             ; Branch if not
>writable
>        MOVL    #SS$_NORMAL,R0          ; Set normal
>completion status
>        RET                             ;  and return
>
>10$:    MOVZWL  #SS$_ACCVIO,R0          ; Indicate access
>violation
>        RET                             ;
>
>        DEFINE_SERVICE USER_SET_PFC,2
>
>        MOVL    8(AP),R6                ; Get address to
>store previous
>value
>        BEQL    10$                     ; Branch if none
>        IFNOWRT #4,(R6),30$             ; Branch if not
>writable
>10$:    MOVL    #SS$_NORMAL,R0          ; Set normal
>completion status
>        RET                             ;  and return
>
>30$:    MOVZWL  #SS$_ACCVIO,R0          ; Indicate access
>violation
>        RET                             ;
>
>        DEFINE_SERVICE USER_NULL
>
>        MOVZWL  #SS$_NORMAL,R0          ; Set normal
>completion status
>        RET                             ;  and return
>;+
>; Any psect with the VEC attribute will be automatically
>moved to the start
> of the image.
>;-
>        .PSECT  USER_SERVICES,PAGE,VEC,PIC,NOWRT,EXE
>
>        .LONG           PLV$C_TYP_CMOD          ; Set type
>of vector to
>change mode dispatcher
>        .LONG           0                       ; Reserved
>        .LONG           KERNEL_ROUTINE_COUNT    ; # of
>Kernel mode routines
>        .LONG           EXEC_ROUTINE_COUNT      ; # of
>Executive mode
>routines
>        .ADDRESS        KERNEL_TABLE            ; Kernel
>routine list
>        .ADDRESS        EXEC_TABLE              ; Exec
>routine list
>        .LONG           0                       ; Kernel
>rundown handler
>        .LONG           0                       ; Exec
>rundown handler
>        .LONG           0                       ; RMS
>Dispatcher
>        .LONG           0                       ; Kernel
>routine flags
>        .LONG           0                       ; Exec
>routine flags
>
>        .END

Care to tell us exactly what your problem is?  If it was the missing ?
on the EACCVIO in the .MACRO definition well, I've already pointed that
out to you.

As for actually probing the argument list, it may not be necessary *IF*
you are homing it.  The calling standard will preserve stack space for
the homed arguments on the stack and the code will place the argument
register values into this reserved stack space before you get to your
probe.  It would seem that if the code can write to this space then you
should also be able to read it.

--
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