Usually people set a switch in the EODAD routine.
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
עַם יִשְׂרָאֵל חַי
נֵ֣צַח יִשְׂרָאֵ֔ל לֹ֥א יְשַׁקֵּ֖ר
________________________________________
From: IBM Mainframe Assembler List <ASSEMBLER-LIST@LISTSERV.UGA.EDU> on behalf
of David Eisenberg <deisenbe...@optonline.net>
Sent: Wednesday, May 8, 2024 6:35 PM
To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: Does the GET macro indicate EOF?
I hope someone can help me; my question pertains to the QSAM GET macro. Please
consider this code snippet:
OPEN SYSIN
GETLOOP GET SYSIN,BUFFER
MYEODAD DS 0H
<branch to label EOF at end-of-file ???>
B GETLOOP
EOF CLOSE SYSIN
*
SYSIN DCB DDNAME=SYSIN,MACRF=GM,DSORG=PS,RECFM=FB,EODAD=MYEODAD,LRECL=80
I've deliberately placed the EODAD address immediately after the GET. My
question: is there anything I can test immediately after the GET to determine
whether a) I successfully read a record, or b) I've reached the EOF?
The IBM manual says that after a GET, R1 points to the record that was read;
however, I don't see any indication in the manual of where R1 points when the
EOF is encountered, nor do I see any return code setting in R15 at EOF. I have
empirically observed that at EOF, R1 points to an area in storage containing
the string 'EOV ', but I don't know if I can rely on that.
Does GET tell me anything when the EOF is reached? Or is there something in the
DCB that I can test to tell me that I'm at the EOF?
(I know that it looks silly to have the EODAD in the middle of the GET loop.
This is about my trying to overcome an IDF limitation regarding
single-stepping.)
Any help would be appreciated; thank you!
David
