On 12/28/2011 2:24 PM, Gainsford, Allen wrote:
Some other interesting instructions in this table:BSG - Branch in Subspace Group EREG - Extract stacked REGisters (32 bits) EREGG - Extract stacked REGisters Grande (64-bits) ESTA - Extract stacked STAte LPTEA - Load Page Table Entry Address MSTA - Modify stacked STAte SSAR - Set Secondary ASN SSAIR - Set Secondary ASN with Instance STRAG - Store Real Address p TAR - Test Access p TPROT - Test PROTection p ('interesting' in the sense they are not semiprivileged and the first eight are not privileged either, but they are described in the chapter on Control Instructions: so are they 'general' instructions? I think not, but it's hard to say.) My focus: are these first eight instructions useful for applications programmers?I have definitely used EREG and EREGG in application programs. If you're calling a subroutine (or entering a subroutine) with BAKR -- not necessarily a good idea, but sometimes useful -- then it can definitely be helpful to modify registers, and still be able to get the calling code's register values back again. Haven't used ESTA and MSTA, but I know they're there if I ever need them. Maybe as a last-ditch way to store a register pair temporarily when there really isn't anything else easily available. By the way, you show TAR as privileged, above, but it doesn't appear to be so.
Whoops! You're right: slipped down when scrolling right with my eyes! Thanks.
Cheers, Allen Gainsford Info Developer, Banking Shared Services HP Enterprise Services (South Pacific) Office +64-4-819-5236 | Fax +64-4-819-5955 | Email [email protected]
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