Hello all,
here's an awkward one I've come across in QLTDis for QL Toady - and I've
figured it out for myself, but I don't like the solution !
ADDQ = 0101 ddd0 ssxx xxxx
SUBQ = 0101 ddd1 ssxx xxxx
Scc = 0101 cccc 11xx xxxx
Where 'ddd' = data and ranges from '000' to '111'
'ss' = size and can be '00', '01' or '10'
'cccc' = condition code and ranges from '0000' to '1111'
'xxxxxx' = effective address = don't care and can be anything !
I have a mask for ADDQ/SUBQ of 1111 0001 0000 0000 which gives 0101 0000
0000 0000 for ADDQ and gives 0101 0001 0000 0000 for SUBQ. Unfortunately, it
also gives 0100 0000 0000 0000 (ie ADDQ) for some Scc instructions and 0100
0001 0000 0000 (SUBQ) for others ! (ADDQ/SUBQ are tested before Scc so we
hit a result for ADDQ/SUBQ before testing for an Scc).
So here is the problem - how to set up my masks and results to get Scc
and/or ADDQ/SUBQ regardless of the order they are tested ?
Simple solution, move Scc above ADDQ/SUBQ in the testing order. Can this be
guaranteed? I've gone cross eyed trying to figure out all the options etc.
I have noticed that the size bits in ADDQ/SUBQ are never '11' and are always
'11' for Scc so I could use this I suppose, but this effectively moves the
ADDQ/SUBQ from type 18 to type 26 and is the same as moving the Scc test
above ADDQ/SUBQ so I'm not fully convinced.
Any offers ?
All gratefully received - I've got spots in front of my (crossed) eyes now
with all this binary stuff.
I need this to get some code written for the next thrilling episode of
QLTdis so quick help very much appreciated.
Regards, Norman
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Norman Dunbar EMail: [EMAIL PROTECTED]
Database/Unix administrator Phone: 0113 289 6265
Lynx Financial Systems Ltd. Fax: 0113 201 7265
URL: http://www.LynxFinancialSystems.com
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