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Zack
160 pts.
 Accessing I/O Feedback Area of DSPF from within CL program
AS/400, CL, Display File, I/O feedback, CL Program, DSPF
Is it possible from within a CL program to retrieve/access the I/O feedback area of a display file (the equivalent of retrieving INFDS (positions 401-404) from within an RPG program)?

Software/Hardware used:
AS400 V6R1
ASKED: May 19, 2011  8:34 AM GMT
UPDATED: June 29, 2011  2:13:23 AM GMT
RELATED QUESTIONS
Bvining
5,870 pts.
Answer Wiki:
I finally got a few free minutes on my system and thought I would answer your original question -- Can you access the I/O feedback area for a *DSPF from a CL program?

The answer is Yes (though as I suggested earlier, it's not exactly direct). Create a *DSPF with SHARE(*YES) specified. If the *DSPF is named CLSHARE then the following code will give you access to the I/O feedback area (with the sample code giving you the aidkey, the cursor location, and the major/minor values).


            Pgm                                                    
                                                                   
            DclF       File(CLShare2)                              
                                                                   
            Dcl        Var(&DspF)      Type(*Char) Len(11)         
            Dcl        Var(&ReadWrite) Type(*Char) Len(4)          
                                                                   
            Dcl        Var(&File_Ptr)  Type(*Ptr)                  
                                                                   
            Dcl        Var(&Cmn_Ptr)   Type(*Ptr)                  
            Dcl        Var(&Cmn_Fdbk)  Type(*Char) Stg(*Based) +   
                                       Len(144) BasPtr(&Cmn_Ptr)   
             Dcl       Var(&Dev_Ofs)   Type(*Int) Stg(*Defined) +  
                                       Len(2) DefVar(&Cmn_Fdbk)    
                                                                   
            Dcl        Var(&Dev_Ptr)   Type(*Ptr)                  
            Dcl        Var(&Dev_Fdbk)  Type(*Char) Stg(*Based) +       
                                       Len(80) BasPtr(&Dev_Ptr)        
             Dcl       Var(&AidKey)    Type(*Char) Stg(*Defined) +     
                                       Len(1) DefVar(&Dev_Fdbk 3)      
             Dcl       Var(&CsrLoc)    Type(*Char) Stg(*Defined) +     
                                       Len(2) DefVar(&Dev_Fdbk 4)      
             Dcl       Var(&Maj_Code)  Type(*Char) Stg(*Defined) +     
                                       Len(2) DefVar(&Dev_Fdbk 35)     
             Dcl       Var(&Mnr_Code)  Type(*Char) Stg(*Defined) +     
                                       Len(2) DefVar(&Dev_Fdbk 37)     
                                                                       
            Dcl        Var(&Null)      Type(*Char) Len(1) Value(x'00') 
                                                                       
            ChgVar     Var(&DspF)      Value('CLSHARE' *Cat &Null)    
            ChgVar     Var(&ReadWrite) Value('ar+' *Cat &Null)         
            CallPrc    Prc('_Ropen') Parm((&DspF) (&ReadWrite)) +      
                                     RtnVal(&File_Ptr)                 
                                                                     
 Loop:      DoWhile Cond(*Not &IN03)                                 
            SndRcvF    RcdFmt(Record)                                
                                                                     
            CallPrc    Prc('_Riofbk') Parm((&File_Ptr *ByVal)) +     
                                      RtnVal(&Cmn_Ptr)               
            ChgVar     Var(&Dev_Ptr) Value(&Cmn_Ptr)                 
            ChgVar     Var(%Ofs(&Dev_Ptr)) Value(%Ofs(&Dev_Ptr) + +  
                          &Dev_Ofs)                                  
                                                                     
            EndDo                                                    
                                                                     
            CallPrc    Prc('_Rclose') Parm((&File_Ptr *ByVal))       
            Return                                                   
                                                                     
            EndPgm


Basically the CL program opens the shared file twice. Once impliciitly and once explicitly using the _Ropen API (which is provided with the operating system and often thought of as being part of C run time). After the user hits enter (or whatever) the program calls the _Riofbk API to access the shared IO feedback area. When you hit the EndDo after this API call you will find that &AidKey holds the aid key value, &CsrLoc the cursor coordinates, etc. The program then simply loops until F3 is used to exit. When exiting the program calls _Rclose to close one instance of the file, and CL implicitly closes the other instance.

Now to go onto your followup clarification on waiting for 60 seconds. You don't need the IO feedback area for that. If you invite the device and no data is available in WAITRCD seconds then the program will receive escape message CPF0889. Monitor for the message and then do whatever you want to do every 60 seconds. The following program still has the code imbedded for IO feedback access, but the MONMSG will get control when the timer expires. To run simply add INVITE to your display file and create the *DSPF with WAITRCD(60) SHARE(*YES). You'll get the time out (and run the UpdateDsp subroutine) or do the normal processing (in this case accessing the IO feedback area).


            Pgm                                                    
                                                                   
            DclF       File(CLShare)                               
                                                                   
            Dcl        Var(&DspF)      Type(*Char) Len(11)         
            Dcl        Var(&ReadWrite) Type(*Char) Len(4)          
                                                                   
            Dcl        Var(&File_Ptr)  Type(*Ptr)                  
                                                                   
            Dcl        Var(&Cmn_Ptr)   Type(*Ptr)                  
            Dcl        Var(&Cmn_Fdbk)  Type(*Char) Stg(*Based) +   
                                       Len(144) BasPtr(&Cmn_Ptr)   
             Dcl       Var(&Dev_Ofs)   Type(*Int) Stg(*Defined) +  
                                       Len(2) DefVar(&Cmn_Fdbk)    
                                                                   
            Dcl        Var(&Dev_Ptr)   Type(*Ptr)                  
            Dcl        Var(&Dev_Fdbk)  Type(*Char) Stg(*Based) +       
                                       Len(80) BasPtr(&Dev_Ptr)        
             Dcl       Var(&AidKey)    Type(*Char) Stg(*Defined) +     
                                       Len(1) DefVar(&Dev_Fdbk 3)      
             Dcl       Var(&CsrLoc)    Type(*Char) Stg(*Defined) +     
                                       Len(2) DefVar(&Dev_Fdbk 4)      
             Dcl       Var(&Maj_Code)  Type(*Char) Stg(*Defined) +     
                                       Len(2) DefVar(&Dev_Fdbk 35)     
             Dcl       Var(&Mnr_Code)  Type(*Char) Stg(*Defined) +     
                                       Len(2) DefVar(&Dev_Fdbk 37)     
                                                                       
            Dcl        Var(&Null)      Type(*Char) Len(1) Value(x'00') 
                                                                       
            ChgVar     Var(&DspF)      Value('CLSHARE' *Cat &Null)     
            ChgVar     Var(&ReadWrite) Value('ar+' *Cat &Null)         
            CallPrc    Prc('_Ropen') Parm((&DspF) (&ReadWrite)) +      
                                     RtnVal(&File_Ptr)                 
                                                                      
 Loop:      DoWhile Cond(*Not &IN03)                                  
            SndF       RcdFmt(Record)                                 
            Wait                                                      
            MonMsg     MsgID(CPF0889) Exec(Do)                        
                       CallSubr Subr(UpdateDsp)                       
                       Iterate CmdLbl(Loop)                           
                       EndDo                                          
                                                                      
            CallPrc    Prc('_Riofbk') Parm((&File_Ptr *ByVal)) +      
                                      RtnVal(&Cmn_Ptr)                
            ChgVar     Var(&Dev_Ptr) Value(&Cmn_Ptr)                  
            ChgVar     Var(%Ofs(&Dev_Ptr)) Value(%Ofs(&Dev_Ptr) + +   
                          &Dev_Ofs)                                   
                                                                      
            EndDo                                                     
                                                                      
            CallPrc    Prc('_Rclose') Parm((&File_Ptr *ByVal))    
            Return                                                
                                                                  
            Subr       Subr(UpdateDsp)                            
            EndSubr                                               
                                                                  
            EndPgm


On V5R4 you will need to create the program with two steps:

CRTCLMOD
CRTPGM ... BNDDIR(QC2LE)

When your system goes to V6R1 you can just use CRTBNDCL

Bruce Vining
Last Wiki Answer Submitted:  May 27, 2011  11:02 PM (GMT)  by  Bvining   5,870 pts.
Latest Answer Wiki Contributors:  TomLiotta   66,765 pts., Cheapgucci   105 pts.
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As far as I know, in order for CL to access the I/O feedback area, you would have to rewrite the program in RPG, COBOL or other HLL. The CL compiler doesn’t provide any pointer or linkage to the I/O feedback area.

Is there specific information that you need from the feedback area? There might be methods of getting the info through other means.

Tom

TomLiotta
 66,765 pts.
 

CL - aka ‘Control Language’ is intended for use in controlling the flow of work / jobs in the machine. If you are using screens - UIM or dspfs pretty much all you need to know at a CL level is reported as a message (MONMSG) or as a data field.

As Tom asked - what is your *real* problem we need to solve?

Yorkshireman
 5,320 pts.
 

Hi Tom and Yorkshireman,

The dspf in question is one that displays the statuses (active, inactive, msgw, etc.) of approximately 40 batch jobs that run continuously and concurrently throughout the day. Unless the user/operator makes an entry from the keyboard, the screen refreshes itself automatically every 60 seconds. What is wanted from the feedback area (major and minor status codes) is the indication that return of control to the CL program is the result of the timeout (and not a keyed-in entry by the user/operator).

Zack

Zack
 160 pts.
 

An alternative solution you might consider would be to create the display file using the DTAQ parameter and specify a data queue that is to be sent a message when input is available from the user. Your program can SND to the *DSPF (not SNDRCV) and then call the QRCVDTAQ API to receive a message from the data queue specifying a 60 second wait time. If the user presses a key QRCVDTAQ will return a message with the value ‘*DSPF in positions 1 - 10. If sixty seconds pass with no operator input then the Length of data parameter returned by QRCVDTAQ will be 0.

If the operator did something, RCV the record format, process the request, SND, and go back to reading from the *DTAQ. If a timeout occured, SND the normal update and go back to reading from the *DTAQ (again with a sixty second wait time).

I do have an idea of how CL might be able to access the *DSPF IO feedback information but haven’t had an opportunity to try it out. It would be more involved though than using a *DTAQ approach.

Bruce Vining

Bvining
 5,870 pts.
 

I should clarify that “a key” in my earlier append means an AID key (Enter, enabled CF key, enabled Roll key, etc).

Bvining
 5,870 pts.
 

Thank you Bruce for your useful suggestion. Your solution would indeed appear to meet the requirement I’m looking for. I will modify the DSPF and CL program accordingly, and try it out. Will come back with an update on its success (or otherwise).

Zack

Zack
 160 pts.
 

Thanks again, Bruce. Your suggestion works and was easy to implement.

Zack

Zack
 160 pts.
 

[...] Accessing I/O Feedback Area of DSPF from within CL program [...]

Featured Member: Bvining - ITKE Community Blog
 0 pts.
 

Bruce,

Only today, a month after you apparently posted your additional response with a CL program to retrieve the I/O feedback area, did I actually see your response. At the moment, we are using the DTAQ implementation but I will save your example and when I get the chance will see that I can make that work as well.

Thanks,
Zack

Zack
 160 pts.
 

Bruce deserves kudos not just for providing an answer, but also for having the courage to post it. I couldn’t convince myself to go with _Riofbk, et al., when the question seemed to be basic. The vagaries of *PTR variables alone had me thinking the thread could go a long way.

I sometimes forget that systems do exist without HLL compilers. Bruce never does.

Tom

TomLiotta
 66,765 pts.