Oppolzer - Informatik / Blog

Sorry ... the LCLA &BITPREF in the second example is no more needed and
misleading ... please remove it ...


Am 31.12.2014 um 00:18 schrieb Bernd Oppolzer:
> I now found the time to test the two variants using my VM/370 R6 installation on
> Hercules.
>
> In fact, the SETA solution does not work, because the value X'80000000' is not
> in the valid range for a SETA symbol (at least with the old ASSEMBLER XF). The
> SETA symbols are limited to 2**31 - 1.
>
> So I found (and tested) the following solution using SETC symbols for the AMODE
> bit (in fact the AMODE nibble):
>
>          LCLC  &AMBIT
>          LCLC  &ZSYS
> &ZSYS    SETC  '370'
> &AMBIT   SETC  '0'
>          AIF   ('&ZSYS' NE '370').BIT24A
> &AMBIT   SETC  '8'
> .BIT24A  ANOP
> NEWIO    DC    X'000C0000'  MACHINE CHECK ENABLED + EC
>          DC    A(X'&AMBIT.0000000'+STAGE2)
> STAGE2   DS    0F
>          END
>
> This solution does not work unmodified with the EQU symbols, because in the 370
> case, the SETC symbols would be redefined, which is not possible for EQU. So the
> AIF logic has to be modified. The EQU logic (which has its merits, too) looks
> like this:
>
>          LCLA  &BITPREF
>          LCLC  &ZSYS
> &ZSYS    SETC  '370'
>          AIF   ('&ZSYS' NE '370').BIT24B
> BITPREF  EQU   X'80000000'
>          AGO   .BIT24A
> .BIT24B  ANOP
> BITPREF  EQU   0
> .BIT24A  ANOP
> NEWIO    DC    X'000C0000'  MACHINE CHECK ENABLED + EC
>          DC    A(BITPREF+STAGE2)
> STAGE2   DS    0F
>          END
>
> I tested this solution, too (simply by looking at the generated machine code,
> that is, hex constants).
>
> Kind regards
>
> Bernd
>
>
>
>
>
> Am 30.12.2014 um 16:50 schrieb Bernd Oppolzer:
> [hercules-os380]:
>> The &s before &BITPREF in SETA were missing in the first try ...
>>
>> Am 30.12.2014 um 16:48 schrieb Bernd Oppolzer:
>>> &BITPREF SETA  0
>>>          AIF   ('&ZSYS' EQ 'S370').BIT24A
>>> &BITPREF SETA  X'80000000'
>>> .BIT24A  ANOP
>>> NEWIO    DC    X'000C0000'  machine check enabled + EC
>>>          DC    A(&BITPREF+STAGE2)
>>>
>>> Kind regards
>>>
>>> Bernd
>>>
>>>
>>> Am 30.12.2014 um 15:29 schrieb K.V.:
>>> [hercules-os380]:
>>>> I wonder if it would be possible to simplify this:
>>>>
>>>> NEWIO    DC    X'000C0000'  machine check enabled + EC
>>>>          AIF   ('&ZSYS' EQ 'S370').MOD24B
>>>>          DC    A(X'80000000'+STAGE2)
>>>>          AGO   .MOD31B
>>>> .MOD24B  ANOP
>>>>          DC    A(STAGE2)
>>>> .MOD31B  ANOP
>>>>
>>>> by having a variable set to either X'00000000'
>>>> or X'80000000'.
>>>>
>>>> Something like:
>>>>
>>>> AIF   ('&ZSYS' EQ 'S370').BIT24A
>>>> BITPREF EQU X'80000000'
>>>> AGO .BIT24B
>>>> BITPREF EQU X'00000000'
>>>> .BIT24B
>>>>
>>>> NEWIO    DC    X'000C0000'  machine check enabled + EC
>>>>          DC    A(&BITPREF+STAGE2)
>>>>
>>>> Would that work?
>>>>
>>>> Thanks. P.
>>>>
>>>>
>>>>