----- "David Bond" <david-b...@comcast.net> wrote: > On Mon, 9 Aug 2010 15:36:43 -0400, Abe Kornelis wrote: > >On Mon, 9 Aug 2010 10:27:08 -0700, Edward Jaffe wrote: > >>Sorry. Don't know the opcode for MVCX. But, since I knew it was > already > >>an assigned instruction mnemonic, I decided to use that name for a > >>macro. If they ever externalize it I'll be "screwed". :-D > > > >Ok, I'll admit MVCX is entirely new to me. > >Never ran into it until just now. > >I can understand the opcode is unknown, > >but would like to find out just what > >we _do_ know about this instruction. > >Is it real? What is it supposed to do? > > There is a millicode-only instruction with a mnemonic of MVCX. It is > used > by millicode for variable-length moves without the need for EX+MVC. > (The > "Execute" instructions are really slow on modern machines.) MVCX is > used by > the millicode for MVCL and other instructions. We know of the MVCX > mnemonic > but not the op-code or the operand format.
This seems like a good instruction for general use, any idea why it was not made available outside of millicode? -- Richard
