On 7/30/2017 6:32 PM, Phil Smith wrote:
Robert Netzloff wrote:
Not sure, but is not MVCL interruptible?
Yes, that one is. Good catch! I've seen it happen, too. Makes sense: you MVCL
more than one page, and one of them is paged out, so it has to stop while the
page fault happens and it comes in. CLCL too, of course. And MVCLE and CLCLE.
No, MVCLE and CLCLE are *not* interruptible. They are far more modern
instructions that move a relatively small number of bytes, update the
registers, and set a condition code that is tested by software for a
loop back if needed. For example:
| DO UNTIL=NO Do for MVCLE
| MVCLE R14,R0,C' ' Copy with blank pad
| ENDDO , EndDo
Such instructions require far less silicon and/or millicode to implement
than the interruptible, 1970s-era MVCL and CLCL instructions.
--
Edward E Jaffe
Phoenix Software International, Inc
831 Parkview Drive North
El Segundo, CA 90245
http://www.phoenixsoftware.com/
