You can have interruptability without an arbitrary length restriction; CLCL and MVCL work just fine. All that you need is that the instruction be resumeable and for the hardware/microcode/millicode to periodically check for pending interrupts and update the registers as needed
-- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 ________________________________________ From: IBM Mainframe Assembler List [[email protected]] on behalf of Robin Vowels [[email protected]] Sent: Friday, April 15, 2022 5:08 AM To: [email protected] Subject: Re: Next instruction needed ----- Original Message ----- From: "Tom Harper" <[email protected]> To: <[email protected]> Sent: Friday, April 15, 2022 3:06 AM > IMHO, the next instruction to add to z/Architecture would be an instruction > to clear storage to > zeros. > Right now a number of methods are in widespread use, none of which are clean > and simple. I mean, > it’s been almost sixty years. > MVCL takes three registers to set up beforehand; So? Write yourself a macro. > XC sets the condition code and is not variable length, and the overlapping > MVC is a kluge But it does the job well. > and not variable length either. Use Ex. > An EX instruction is also a kluge. > All you need is the address and length to accomplish this, preferably in two > versions, > one with an immediate operand for the length Really?! A few lines ago, you were decrying XC and MVC because they have a "fixed length". > and another which uses, for example, a register, perhaps register zero. A > long displacement would > be a plus. To avoid issues with interruptibility, the length would need to be limited to 256 bytes. What? Back to a limit of 256? what's the point of that? MVCL will do as long as you want. > I don’t think the length restriction would be an issue in most cases. There's no point in having an instruction with a length restrictionof 256. > Such an instruction might look like this: > CLEAR FieldA >Or > LLGF R0,Varlen > CLEARR A macro reference would require one line. > Similar instructions for compare logical and move would be nice as well. --- This email has been checked for viruses by Avast antivirus software. https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.avast.com%2Fantivirus&data=05%7C01%7Csmetz3%40gmu.edu%7C321a88f8873f489ae2aa08da1ebf8695%7C9e857255df574c47a0c00546460380cb%7C0%7C0%7C637856105217726958%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=1YlHbddJyGWkzKpajlykSLpgYc4F%2B%2BF26AYQ%2FgecQ78%3D&reserved=0
