🚀 go-pugleaf

I think it was public-spirited of Ed to provide a non-reentrant example too.
  I would not have bothered to do so, in part at least because I'm not sure
I want people who write non-reentrant code using AMODE(64) just yet.

John Gilmore
Ashland, MA 01721
USA





>From: Steve Comstock <steve@trainersfriend.com>
>Reply-To: IBM Mainframe Assembler List <ASSEMBLER-LIST@listserv.uga.edu>
>To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
>Subject: Re: SAVE/RETURN macros in AMODE 64
>Date: Fri, 16 Sep 2005 15:00:26 -0600
>
>Edward E. Jaffe wrote:
>>Steve Comstock wrote:
>>
>>>          LARL  R12,TEST64
>>>          USING *,R12
>>
>>
>>
>>Ignoring the fact that the above USING is wrong, 64-bit programs are
>>intended to use relative addressing. Thus, the base register would
>>normally cover constants and literals only (for reentrant code) and the
>>work area (for non-reentrant code). That is, under normal circumstances,
>>the LARL would not point to the start of the program. I believe these
>>examples may be somewhat more typical:
>>
>>Reentrant code:
>>|         LARL  R12,TEST64_Const    Point to constants area
>>|         USING TEST64_Const,R12    Synchronize base register
>>|         STORAGE OBTAIN,           Acquire the work area
>>|               LENGTH=WKAREA_LEN   Acquire work area
>>|         STG   R1,136(,R13)        Chain save areas
>>|         STG   R13,128(,R1)        (same)
>>|         LGR   R13,R1              Get area address in R13
>>|         USING WKAREA,R13          Synchronize WKAREA
>>|         .
>>|         .
>>|               CNOP  0,8           Align to doubleword
>>|TEST64_Const   DC    0D            Begin constants area
>>|               .
>>|               .
>>|               LTORG ,             Define literals
>>|
>>|WKAREA         DSECT ,             Program work area DSECT
>>|               DS    18D           Program save area
>>|               .
>>|               .
>>|WKAREA_LEN     EQU   *-WKAREA      Length of work area
>>
>>
>>Non-reentrant code:
>>|         LARL  R1,TEST64_Const     Point to constants area
>>|         STG   R1,136(,R13)        Chain save areas
>>|         STG   R13,128(,R1)        (same)
>>|         LGR   R13,R1              Get area address in R13
>>|         USING TEST64_Const,R13    Synchronize base register
>>|         .
>>|         .
>>|               CNOP  0,8           Align to doubleword
>>|TEST64_Const   DC    0D            Begin constants area
>>|               DC    18D'0'        Define program save area
>>|               .
>>|               .
>>|               LTORG ,             Define literals
>
>
>Well, good point. But I focus on using the relative addressing
>approach in other places. Just trying to respond to the OP
>(but blew it with the USING). Otherwise, there was no
>context in his example to tell us what was needed.
>
>[BTW, I thought you only coded reentrant code these days?]
>
>Kind regards,
>
>-Steve

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