Re: How bad is the EX instruction?

2012-01-16 Thread Tom Marchant
On Fri, 13 Jan 2012 18:29:55 -0800, glen herrmannsfeldt wrote: The EX CLC is in fact in loop scanning a linked list for the right entry among 100-200 elements. You could also do binary search, which will find the right entry with about log(n) comparisons. How do you do a binary search on a

Re: How bad is the EX instruction?

2012-01-16 Thread Dan Skomsky, PSTI
One Assembler trick I have seen in speeding up scanning loops was to use a CLI instruction to check the first byte of a string and then only doing the CLC/CLCL if the CLI matches. This trick even works if doing a binary search. -Original Message- From: IBM Mainframe Assembler List

Re: How bad is the EX instruction?

2012-01-16 Thread Rob van der Heij
On Sat, Jan 14, 2012 at 3:29 AM, glen herrmannsfeldt g...@ugcs.caltech.edu wrote: I usually use a hash table. Especially if speed is important. You could also do binary search, which will find the right entry with about log(n) comparisons. Yeah, and I prefer to stop the earth rotation when I

Re: How good is the EX instruction?

2012-01-16 Thread robin
From: Dan Skomsky, PSTI poodles...@sbcglobal.net Sent: Monday, 16 January 2012 11:49 PM One Assembler trick I have seen in speeding up scanning loops was to use a CLI instruction to check the first byte of a string and then only doing the CLC/CLCL if the CLI matches. This trick even works if

Re: How bad is the EX instruction?

2012-01-16 Thread Tom Marchant
On Mon, 16 Jan 2012 06:49:54 -0600, Dan Skomsky, PSTI wrote: One Assembler trick I have seen in speeding up scanning loops was to use a CLI instruction to check the first byte of a string and then only doing the CLC/CLCL if the CLI matches. This trick even works if doing a binary search. I

Re: How bad is the EX instruction?

2012-01-16 Thread Rob van der Heij
On Mon, Jan 16, 2012 at 4:13 PM, Tom Marchant m42tom-ibmm...@yahoo.com wrote: On Mon, 16 Jan 2012 06:49:54 -0600, Dan Skomsky, PSTI wrote: One Assembler trick I have seen in speeding up scanning loops was to use a CLI instruction to check the first byte of a string and then only doing the

Re: Enhanced CALL macro?

2012-01-16 Thread Ray Mullins
And YREGS. On 2012-01-12 21:17, Hall, Keven wrote: Have you forgotten about SAVE and RETURN in SYS1.MACLIB? IBM has you covered. Mostly covered, sort of...ish. K3n -Original Message- From: IBM Mainframe Assembler List [mailto:ASSEMBLER-LIST@LISTSERV.UGA.EDU] On Behalf Of Paul

Re: How bad is the EX instruction?

2012-01-16 Thread Ray Mullins
On 2012-01-13 02:18, Rob van der Heij wrote: On Fri, Jan 13, 2012 at 8:13 AM, Martin Truebnermar...@pi-sysprog.de wrote: Rob, have you tried SRST? I had a hard time getting used to SRSTs way of using/wanting the resgisters- but then... It does an excellent job on searching for one (and only

Re: How bad is the EX instruction? (correction)

2012-01-16 Thread Ray Mullins
Arrgh. Correction to the below. Not enough caffeine, yet it's late in the morning... Tom Marchant correctly mention that SRST/CLST came in with ESA, not late System/370, as a look at my SEARS card just confirmed. However, the point still applies - SRST/CLST have been around for almost 25 years

Re: How bad is the EX instruction?

2012-01-16 Thread Paul Gilmartin
On Jan 16, 2012, at 05:35, Tom Marchant wrote: On Fri, 13 Jan 2012 18:29:55 -0800, glen herrmannsfeldt wrote: The EX CLC is in fact in loop scanning a linked list for the right entry among 100-200 elements. You could also do binary search, which will find the right entry with about log(n)

Re: How good is the EX instruction?

2012-01-16 Thread Paul Gilmartin
On Jan 16, 2012, at 07:53, robin wrote: From: Dan Skomsky, PSTI poodles...@sbcglobal.net Sent: Monday, 16 January 2012 11:49 PM One Assembler trick I have seen in speeding up scanning loops was to use a CLI instruction to check the first byte of a string and then only doing the CLC/CLCL if

How do you do a binary search on a linked list?

2012-01-16 Thread John Gilmore
Binary search of an ORDERED linked list is in fact possible if one knows/keeps track of how many elements the list contains. It may even be be a useful thing to do when pointer-chasing operations are very much faster than key-comparison operations, as they are in, say, C. My gut feeling about

Re: How bad is the EX instruction? (correction)

2012-01-16 Thread Tony Thigpen
I doubt anyone is still running ES 9000 boxes. I have paying customers on 9672s, MP2000, MP3000, etc. VSE, not z/OS. Tony Thigpen -Original Message - From: Ray Mullins Sent: 01/16/2012 01:48 PM Arrgh. Correction to the below. Not enough caffeine, yet it's late in the morning...

Re: How bad is the EX instruction?

2012-01-16 Thread Kerry
Saying that ... sub-optimizing of this sort is, I think, evidence of a pervasive malaise... is a short sighted generalization. Performance is one of the strongest reasons for coding in assembler and this discussion characterizes some of the low hanging fruit available for the attainment thereof.

Re: How good is the EX instruction?

2012-01-16 Thread robin
From: Rob van der Heij rvdh...@gmail.com Sent: Tuesday, 17 January 2012 2:37 AM Having the CLC near the EX helps for cache. I also like to assemble it in-line because the right USINGs apply. We noticed that it is attractive to run over the CLC (with the length byte 0 as assembled) and then EX

Re: How good is the EX instruction?

2012-01-16 Thread robin
From: Paul Gilmartin paulgboul...@aim.com Sent: Tuesday, 17 January 2012 7:33 AM CDC 3600/3800 had a Modify following instruction instruction The S/360 and subsequent machines have one like that also. In the case of MVC/CLC instructions :- stc 1,*+5 mvc a(0),b can be useful. EX does more

Re: How good is the EX instruction?

2012-01-16 Thread robin
From: McKown, John john.mck...@healthmarkets.com Sent: Friday, 13 January 2012 2:32 AM OK, I hope I'm not becoming wearisome with my yammering. But I am not too busy right now. And I still really like and respect the z architecture (despite its horrendous price). I ask about the CPU cost of