Or, if unsigned, use LLC -----Original Message----- From: IBM Mainframe Assembler List [mailto:[email protected]] On Behalf Of John McKown Sent: 03 June 2014 15:12 To: [email protected] Subject: Re: Out of Order and Superscalar - small experiment
On Tue, Jun 3, 2014 at 7:57 AM, Steve Hobson <[email protected]> wrote: > >From: "Rob van der Heij" <[email protected]> > >Sent: Tuesday, June 03, 2014 1:00 AM > > > >Must have muissed something here. > >A 3-instruction loop to sum bytes. > > > > LA 6,X+offset (last byte of area to be summed) > > SR 2,2 > > SR 4,4 > >Loop IC 4,0(0,6) > > AR 2,4 > > BCT 6,Loop > > > >And you can use BCTR to save a few µS. > > Sorry to be picky but unless the string starts at location zero I > think you need: > > LA 6,X (address of area to be summed) > LA 7,offset (offset to last byte of area to be summed) > SR 2,2 > SR 4,4 > Loop IC 4,0(7,6) > AR 2,4 > BCT 7,Loop > > > Best regards, Steve Hobson > CICS Strategy, HLASM Development, Master Inventor Hursley > Laboratories, MP 189, Room A4126, UK > Tie: 246894 International: +44 1962 81 6894 > > Je me presse de rire de tout, de peur d'être obligé d'en pleurer > Unless stated otherwise above: > IBM United Kingdom Limited - Registered in England and Wales with > number 741598. > Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 > 3AU > Both of the examples assume that the data value is _unsigned_, or is less than or equal to 127 (0x7F). If this is not true, then I will insert a slightly different solution: LA 6,X (address of area to be summed) LA 7,offset (offset to last byte of area to be summed) SR 2,2 * SR 4,4 Not needed because LB does sign extension. Loop LB 4,0(7,6) Not sure when this came in. AR 2,4 BCT 7,Loop -- There is nothing more pleasant than traveling and meeting new people! Genghis Khan Maranatha! <>< John McKown
