On Sun, 17 Aug 2014 17:25:34 -0600 Paul Gilmartin
<[email protected]> wrote:
:>On 2014-08-17, at 16:43, J R wrote:
:>> Binyamin suggested an S-con 0S(expression)
:>> which would contain a base and displacement
:>> BDDD. By "absolute value" the base would be zero.
:>I believe the only way to force an S-con to use a
:>zero base is by DROPping all extant base registers.
:>Otherwise the S-constant is free to use any available
:>base to resolve the expression. Perhaps Binyamin
:>meant to imply a PUSH-DROP-0S(EXPRESSION)-POP sequence.
:>The unwary user should at least be warned of this.
If the result of the expression is an absolute (non-relocatable) address, the
only way a base would be possible is if something like
USING x'7fffC000',Rx,Ry.Rz
is issued.
But at any rate, I commonly will use something like ...
SYSTEM-Exit
L Rx,work-area-pointer
USING work-exit-dsect,Rx
work-area-dsect DSECT
various fields
work-area-len EQU *-workarea-dsect required length
DC S(256-work-area-len) generate assembly error if DSECT
bigger than passed work-area
If work-area-len if 278, the resultant SCON for -22 is not resolvable and will
cause an assembly error
--
Binyamin Dissen <[email protected]>
http://www.dissensoftware.com
Director, Dissen Software, Bar & Grill - Israel
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