IBM Mainframe Forum

by **helen2000** » Thu Apr 01, 2010 1:15 am

could anybody answer the question? thanks, by the way, could you code a sample program to test your answer, thanks, Helen

Given N DC CL5'10639'.
Given Z DC PL3'-12', Show the hex representation of Z before and after PACK N,Z.

by **dick scherrer** » Thu Apr 01, 2010 1:25 am

Hi Helen,

Suggest you write the code you want, write the output from the PACK to a record in a file, and then view the file in hex.

Post back here if there are any questions/problems.

by **helen2000** » Thu Apr 01, 2010 2:48 am

Hi, Mr. Dick
this is test code:

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OPEN REPORT
PUT REPORT,OREC
PACK ONN,OZZ
PUT REPORT, OREC
CLOSE REPORT
....
OREC DS 0CL16
ONN DC CL5'10639'
DC CL3'***'
OZZ DC PL3'-12'
DC CL3'***"
END

The following is output:

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000001 10639*** ***
FFFFF5550025554444444444444444444444
10639CCC01DCCC0000000000000000000000
-------------------------------------------
000002 K*** ***
0000D5550025554444444444444444444444
00012CCC01DCCC0000000000000000000000
-------------------------------------------
****** **************************** Bottom

please explain why 00012d change to 00000001d2 after packed, thanks,
Helen

by **Frank Yaeger** » Thu Apr 01, 2010 3:11 am

From the POP:

PACK D1(L1,B1),D2(L2,B2) [SS]

The format of the second operand is changed from zoned to packed, and the result is placed at the first-operand location. The zoned and packed formats are described in Chapter 8, "Decimal Instructions."
The second operand is treated as having the zoned format.
********************************
The second operand is supposed to be the ZD source value and the first operand is supposed to be the PD target value. You have the reverse. Your PACK instruction should be:

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PACK OZZ,ONN

Also, for:

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OZZ DC PL3'-12'
DC CL3'***"

You need an ending apostrophe after *** instead of an ending quote.

by **dick scherrer** » Thu Apr 01, 2010 3:12 am

Hi Helen,

Suggest you reverse the operands in the PACK instruction and specify the length.

by **helen2000** » Thu Apr 01, 2010 3:39 am

this is a homework from the textbook written by Bill Qualls(chapter 7---7.6), I know if reverse the operands it will work well.
but for the case, I confuse the output: ooo12D change to 00000001D2? I think it must be for some reason I don't know, I'm
sorry I'm a beginner for assembler language, thanks,
Helen.

by **Frank Yaeger** » Thu Apr 01, 2010 4:09 am

00012D change to 00000001D2

Here's the explanation for that:

Your original PACK instruction said you wanted to convert the original 3 byte "ZD value" at OZZ to a 5 byte PD value at ONN.

Your 3-byte "ZD value" at OZZ is the following in hex:

00012D

A 3-byte ZD value looks like this:

zdzdsd

where z is the zone (ignored), d is a digit (0-9) and s is the sign.

PACK converts your zdzdsd value to a ddds value. It removes the zones, keeps the digits, and reverses the sign and last digit.

So 00012D is converted to 01D2. However, since your PD value is 5 bytes, it is padded with decimal zeros on the left to 5 bytes to get 00000001D2

Make sense?

by **helen2000** » Thu Apr 01, 2010 8:08 pm

at first, thanks Mr. Frank, It's right where I confused. so, I have
OZZ DC PL3'-14312', should be got 41d2 after packed. but the output is totally different, more confuse, why,

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OPEN REPORT
PUT REPORT,OREC
PACK ONN,OZZ
PUT REPORT, OREC
CLOSE REPORT
....
OREC DS 0CL16
ONN DC CL5'10639'
DC CL3'***'
OZZ DC PL3'-14312'
DC CL3'***"
END

and this is output

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000001 10639*** ***
FFFFF5550025554444444444444444444444
10639CCC00DCCC0000000000000000000000
-------------------------------------------
000002 K*** ***
0000D5550025554444444444444444444444
00002CCC00DCCC0000000000000000000000
-------------------------------------------
****** **************************** Bottom

could you tell me maybe my test code have problem, thanks?

by **Frank Yaeger** » Thu Apr 01, 2010 9:37 pm

Yes, 41D2 would be expected and when I run what you show for your program, that's what I get:

X'00000041D25C5C5C...'

I don't know what you're doing that gave X'00000000D25C5C5C...' instead. There's something you're not showing. Are you doing anything later on in the program that would overlay bytes in OREC?

I did notice that for the second PUT you show

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PUT REPORT, OREC

instead of:

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PUT REPORT,OREC

but I don't know if that's what you really have or whether that would cause the difference you're seeing.

If you can't figure out what you're doing different, show your Assembler listing.

by **helen2000** » Thu Apr 01, 2010 11:11 pm

may be it's because I use pc/370 assembler , the software is from author Bill Qualls. I ftp the report.txt to mainframe to check.
the following is the whole test code. please tell me if found some problem, thanks,

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PRINT NOGEN
START 0
REGS
BEGIN BEGIN
WTO 'PATEST ... Begin execution'
OI REPORT+10,X'08' PC/370 ONLY - Convert all
* output from EBCDIC to ASCII
OPEN TEACHERS
OPEN REPORT
MVC OCRLF,WCRLF
PUT REPORT,OREC
PACK ONN,OZZ
PUT REPORT,OREC

*
* EOJ processing
*
ATEND CLOSE TEACHERS
CLOSE REPORT
WTO 'PUTPUT....... list on REPORT.TXT'
WTO 'PATEST ... Normal end of program'
RETURN
*
* Literals, if any, will go here
*
LTORG
*
* File definitions
*
TEACHERS DCB LRECL=29,RECFM=F,MACRF=G,EODAD=ATEND,
DDNAME='TEACHER.DAT'
REPORT DCB LRECL=16,RECFM=F,MACRF=P,
DDNAME='REPORT.TXT'
*
* Miscellaneous field definitions
*
WCRLF DC X'0D25' PC/370 ONLY - EBCDIC CR/LF
* Output (line) definition
*
OREC DS 0CL16
ONN DC CL5'10639'
DC CL3'***'
OZZ DC PL3'-14312'
DC CL3'***'
OCRLF DS CL2 PC/370 only - CR/LF
END BEGIN

Helen

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