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DSECT and Establishing Addressability


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vinayknj

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Joined: 26 May 2008
Posts: 50
Location: Bangalore

PostPosted: Tue May 31, 2011 3:45 pm
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Hi,

I have written below code to understand the concept of DSECT and establishing addressability for DSECT.

But the compilation error says No Active USING for the fields under DSECT(OPERTNA,ADD1A,ADD2A).

Code:
TESTPGM2 START
         SAVE (14,12)   
         USING *,R5     
         BALR R5,R0     
         BCTR R5,R0     
         BCTR R5,R0     
         OPEN (OUTFLE,OUTPUT) 
ADDIT    MVC OPERTN,=C'ADD'   
         L R2,ADD1   
         AH R2,ADD2                                               
         CHI R2,50                                                 
         BE  ADDSUC                                               
         WTO 'FAIL:ADDITION(AH) OF X''31 WITH X''14 IS NOT X''45'''
         B  DISP                                                   
ADDSUC   WTO 'SUCC:ADDITION(AH) OF X''31 WITH X''14 IS X''45'''   
DISP     LA R3,RESULT                                             
         ST R2,0(R3)                                               
         PUT OUTFLE,ADDDATE                                       
         WTO '***DSECT AND ADDRESSABILITY***'           
ADD      USING ADDFLD,R9                               
         L  R9,OUTREC                                   
         MVC OPERTNA,=C'ADD'                           
         L R2,ADD1A                                     
         MVI ADD2A,10                                   
         AH  R2,ADD2A                                   
         CHI R2,40                                     
         BE  ADDSUC                                     
         WTO 'FAIL:ADDITION(AH) OF 30 WITH 10 IS NOT 40'
         B  DISP                                       
ADDSUC2  WTO 'SUCC:ADDITION(AH) OF 30 WITH 10 IS 40'   
DISP2    LA R3,RESULTA                                 
         ST R2,0(R3)                                   
         PUT OUTFLE,OUTREC                             
         CLOSE OUTFLE                                   


* DATA FIELDS FOR AH INSTRUCTION             
ADDDATE  DC 0CL80                             
OPERTN   DC CL3' '                           
FILLER1  DC C' '                             
ADD1     DC F'30'                             
FILLER2  DC C' '                             
ADD2     DC H'20'                             
FILLER3  DC C' '                             
RESULT   DC F'0'                             
FILLER4  DC CL64' '                           

OUTREC   DC  CL80' '                                                   
OUTFLE   DCB DSORG=PS,                                                 X
               MACRF=(PM),                                             X
               DDNAME=OUTFILE,                                         X
               LRECL=80,                                               X
               RECFM=FB,                                               X
               SYNAD=ERROR1,                                           X
               BLKSIZE=8000                                             

ADDFLD   DSECT         
OPERTNA  DC CL3' '     
FILLER1A DC C' '       
ADD1A    DC F'30'       
FILLER2A DC C' '       
ADD2A    DC H'20'       
FILLER3A DC C' '       
RESULTA  DC F'0'       
FILLER4A DC CL64' '     
*                       
         END           


But the compilation error says No Active USING for the fields under DSECT(OPERTNA,ADD1A,ADD2A).

Please let me know what is wrong with the code. Thanks
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Robert Sample

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Posts: 8651
Location: Dubuque, Iowa, USA

PostPosted: Tue May 31, 2011 3:57 pm
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You have to allocate memory pointed to by a register, then issue a USING ADDFLD,register to make the DSECT variables usable -- BEFORE using any of the variables.
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Bill O'Boyle

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PostPosted: Tue May 31, 2011 3:58 pm
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First of all, get rid of those two consecutive BCTR's. What are they for?

Second, I don't see a USING and an associated base-register for the ADDFLD DSECT.

DSECT's belong at the top, before the start of the CSECT, but that has nothing to do with the USING error.

Issue a GETMAIN and then load R9 (as an example DSECT base) from R1 with the address, followed by USING ADDFLD,R9. You're also missing an 18-Word Register-Savearea (standard practice) and the RETURN Macro with an accompanying R15.

Bill
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Garry Carroll

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Location: Dublin, Ireland

PostPosted: Tue May 31, 2011 4:05 pm
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Quote:
DSECT's belong at the top, before the start of the CSECT

Not at my shop. Every in-house Assembler application has the DSECTs at the bottom. I think it's according to taste...

Garry.
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PeterHolland

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Posts: 2480
Location: Netherlands, Amstelveen

PostPosted: Tue May 31, 2011 4:26 pm
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You are using a labeled USING so you would need someting like :

MVC ADD.OPERTNA,=C'ADD'

better is :

ADD EQU *
USING ADDFLD,R9


And for the rest your coding sucks big time.
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Bill O'Boyle

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PostPosted: Tue May 31, 2011 4:33 pm
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Garry,

HLASM recommends placing the DSECTS at the top. This is just the opposite of its predecessors.

DSECTS at the top prevent the Assembler from "Double Sweeping" during Assembly.

Bill
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Bill O'Boyle

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Location: Atlanta, Georgia, USA

PostPosted: Tue May 31, 2011 4:45 pm
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Something else. Move the BALR R5,R0 to just after the SAVE Macro, then followed by the USING for the CSECT.

Change L R9,OUTREC to LA R9,OUTREC

Bill
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nigelosberry

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Joined: 06 Jan 2009
Posts: 88
Location: Ggn, IN

PostPosted: Wed Jun 01, 2011 2:46 pm
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Code:
ADDFLD   DSECT         
OPERTNA  DC CL3' '     
FILLER1A DC C' '       
ADD1A    DC F'30'       
FILLER2A DC C' '       
ADD2A    DC H'20'       
FILLER3A DC C' '       
RESULTA  DC F'0'       
FILLER4A DC CL64' '     



Shouldn't all DC's be DS's here? I believe that DSECT acts just as a "stencil" over a data area and does nothing like initialising that area.
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nigelosberry

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PostPosted: Wed Jun 01, 2011 2:52 pm
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Code:
BCTR R5,R0     
BCTR R5,R0     


A different way of adjusting the address in base register.

I once placed a BALR after USING and it took me quite long to detect the problem.
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Garry Carroll

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PostPosted: Wed Jun 01, 2011 2:55 pm
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Quote:
A distinct way of adjusting the base register address.


No, an unconventional way. Most would

Code:
    TESTPGM2 CSECT
             L    R5,R15
             USING TESTPGM2,R5


Garry.
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nigelosberry

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PostPosted: Wed Jun 01, 2011 2:58 pm
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Garry Carroll wrote:
Quote:
A distinct way of adjusting the base register address.


No, an unconventional way. Most would

Code:
    TESTPGM2 CSECT
             L    R5,R15
             USING TESTPGM2,R5


Garry.



Yes. absolutely!
One should not reach a point wherein one has to adjust the content of base. icon_smile.gif
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vinayknj

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PostPosted: Wed Jun 15, 2011 10:52 am
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Thanks everyone. The issue is resolved, as mentioned by Peter I would have to use ADD.OPERTNA.
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