> -----Original Message----- > From: IBM Mainframe Discussion List > [mailto:[email protected]] On Behalf Of Sam Siegel > Sent: Tuesday, February 16, 2010 1:44 PM > To: [email protected] > Subject: Re: Fastest branch instruction > <snip> > > You may want to look at some of the new compare instructions > such as compare > logical immediate and branch relative. The branch is > generated inside the > instructions when the comparison fails.
Those a z10 only. We are stuck for who knows how long on a __purchased__ z9BC. > > You may also want to try an experiment with compare halfword > immediate. (I > know it is a signed compare but since your are testing for > equal/not equal > you should be ok.) You can compare two bytes at a time. > Along those lines, > depending on occurrences and lengths of blank character runs > you may want to > pre-load a 32 or 64 bit register w/spaces and then fetch 4 or > 8 bytes at a > time and do a compare logical register. Be sure to only > start fetching once > the source is on a word or double word boundary ... otherwise > register load > performance will suffer. Basically you will need to use a > CLI loop until > you get to the correct boundary. Hum, an interesting thought, for sure! > > Compile a C or Metal-C program with memcmp under high > optimization and the > correct arch level. Take a close look at the generated code. > Try it with a > fixed length target (char a[ 10 ]) and a variable length > object (char *a). > The code is very interesting. No C compiler here. No money, either. > > Cheers > Sam -- John McKown Systems Engineer IV IT Administrative Services Group HealthMarkets(r) 9151 Boulevard 26 * N. Richland Hills * TX 76010 (817) 255-3225 phone * (817)-961-6183 cell [email protected] * www.HealthMarkets.com Confidentiality Notice: This e-mail message may contain confidential or proprietary information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. HealthMarkets(r) is the brand name for products underwritten and issued by the insurance subsidiaries of HealthMarkets, Inc. -The Chesapeake Life Insurance Company(r), Mid-West National Life Insurance Company of TennesseeSM and The MEGA Life and Health Insurance Company.SM ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
