Or a more practical use of LAE
Is chaing thru control blocks from another address space SAC. 512 LAM R3,R3,ASNALET L. R3,ASXBFTCB USING TCB,R3 LAE. R4,TCBRBP USING R4,RB Sent from my iPhone On Mar 6, 2012, at 5:53 PM, Rob Scott <rsc...@rocketsoftware.com> wrote: > Micheal, > > Putting a bit of "meat on the bones" to create an example piece of code with > comments and notes : > > (o) We are going to process a linked list of "FOO" elements in a dataspace > and calculate some random hash value based on a subset of bytes in the > FOO_NAME field. > (o) This code has been just typed into my e-mail - they may be typos/errors > (o) "WA" is the working storage structure/DSECT > > > DO , > ALESERV ADD,STOKEN=WA_FOO_STOKEN, Add dataspace containing linked > list of FOOs > ALET=WA_FOO_ALET, > AL=WORKUNIT, > MF=(E,WA_ALESERV_LIST) > DOEXIT (LTR,R15,R15,NZ) Failed - quick exit > SAC 512 AR-Mode (1) > SYSSTATE ASCENV=AR Inform assembler of AR-mode > L R6,WA_FOO_HEAD Get head of list > LAM AR6,AR6,WA_FOO_ALET Get dataspace ALET (2) > USING FOO,R6 > DO UNTIL=(ICM,R6,B'1111',FOO_NEXT,Z) Traverse list (3) > LAE R7,FOO_NAME Point to FOO_NAME (4) > LAE R1,8(,R7) Use R1 for temp pointer (5) > XC WA_HASH,WA_HASH Zero hash value > DO FROM=(R14,=AL4(L'FOO_NAME-8)) > XR R0,R0 > IC R0,0(,R1) Get 1-byte (6) > AL R0,WA_HASH Add to hash value > ST R0,WA_HASH Store new value > LAE R1,1(,R1) Next byte of name (6) > ENDDO > NC WA_HASH,=X'000000FF' 0-255 range for hash > ENDDO > SAC 0 Inform assembler (7) > SYSSTATE ASCENV=P > ENDDO (8) > > ....rest of code (9) > > Notes : > > (1) I think it is always worth having a macro to do both the SAC and the > SYSSTATE for you in one hit (not shown)- stops you forgetting the SYSSTATE > and that can confuse any macros that follow. > (2) Loading the ALET in to the AR for the first time - R6 will be able to > address data in the dataspace > (3) AR-mode makes traversing data structures in dataspaces easy as you can > just use normal instructions (if you play by the rules) > (4) Because LAE used and FOO dsect covers R6+AR6 - AR7 will contain ALET for > dataspace after instruction executed > (5) This time we are using R1 to point at 8 bytes into FOO_NAME (for whatever > reason) - note that AR1 will get the dataspace ALET > (6) Loading and using a byte from the dataspace > (7) See (1) > (8) Assuming all ARs are zero before we start, if the code goes thru > successfully, then AR1, AR6 and AR7 will contain the ALET of the dataspace > here - you may wish to consider zeroing the ARs at this point if they are no > longer needed. > (9) Prudent use of "LAM AR14,AR1,=4A(0)" will protect you from > unintentional AR values in "working" regs after calling certain system > services - you can never be sure how in-house macros expand. > > Hope this helps > > > Rob Scott > Lead Developer > Rocket Software > 275 Grove Street * Newton, MA 02466-2272 * USA > Tel: +1.781.684.2305 > Email: rsc...@rs.com > Web: www.rocketsoftware.com > > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf > Of Micheal Butz > Sent: 06 March 2012 21:53 > To: IBM-MAIN@bama.ua.edu > Subject: Re: LAE instruction > > So SAC 512 > LAE R3,0(,R4) > > R3 is CPYA from access R4 right > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf > Of McKown, John > Sent: Tuesday, March 06, 2012 4:22 PM > To: IBM-MAIN@bama.ua.edu > Subject: Re: LAE instruction > > Yes, from the LAE instruction text: > > <quote> > The address specified by the X2, B2, and D2 fields is placed in general > register R1. Access register R1 is loaded with a value that depends on the > current value of the address-space-control bits, bits 16 and > 17 of the PSW. If the address-space-control bits are > 01 binary, the value placed in the access register also depends on whether > the B2 field is zero or non- zero. > > ... > > PSW Bits > 16 and 17 > Value Placed in Access Register R1 > 00 00000000 hex (zeros in bit positions 0-31) > > 10 00000001 hex (zeros in bit positions 0-30 and one in bit position 31) > > 01 If B2 field is zero: 00000000 hex (zeros in bit positions 0-31) If B2 > field is nonzero: Contents of access register B2 > > 11 00000002 hex (zeros in bit positions 0-29 and 31, and one in bit position > 30) > > From the SAC instruction > > Code Name of Mode Result in PSW Bits 16 & 17 > 0000 Primary space 00 > 0001 Secondary space 10 > 0010 Access register 01 > 0011 Home space 11 > All others Invalid > > </quote> > > SAC 512 has is '0010' from the above and results in b'01' or AR mode in the > PSW bits 16 & 17. Which is what is required for the LAE instruction to set > the access register of the result access register from the base access > register (when not b'0000'). > > > > John McKown > > Systems Engineer IV > > IT > > > > Administrative Services Group > > > > HealthMarkets(r) > > > > 9151 Boulevard 26 * N. Richland Hills * TX 76010 > > (817) 255-3225 phone * > > john.mck...@healthmarkets.com * 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 > > > >> -----Original Message----- >> From: IBM Mainframe Discussion List >> [mailto:IBM-MAIN@bama.ua.edu] On Behalf Of Micheal Butz >> Sent: Tuesday, March 06, 2012 3:00 PM >> To: IBM-MAIN@bama.ua.edu >> Subject: Re: LAE instruction >> >> John Mckiwns reply was a explanation of the SAC inst. >> Which I am aware of >> >> The Doc for LAE says the inst the functionality is dependent on PSW >> bits >> >> 16 17 address space control bits these are set by the SAC inst >> >> >> So my original question remains does >> >> Should address space control buts be set via the sac before executing >> the LAE >> >> >> Sent from my iPhone >> >> On Mar 6, 2012, at 3:37 PM, Rob Scott <rsc...@rocketsoftware.com> >> wrote: >> >>> John McKown's reply covered these points very well >>> >>> Rob Scott >>> Lead Developer >>> Rocket Software >>> 275 Grove Street * Newton, MA 02466-2272 * USA >>> Tel: +1.781.684.2305 >>> Email: rsc...@rs.com >>> Web: www.rocketsoftware.com >>> >>> >>> -----Original Message----- >>> From: IBM Mainframe Discussion List >> [mailto:IBM-MAIN@bama.ua.edu] On Behalf Of Micheal Butz >>> Sent: 06 March 2012 19:59 >>> To: IBM-MAIN@bama.ua.edu >>> Subject: Re: LAE instruction >>> >>> Thanks >>> >>> Regarding my questions >>> >>> The doc says the inst is dependent >>> On address space control bits which is set by the SAC inst. >>> >>> Secondly seems like the displacement doesn't play a role in the inst >>> >>> Sent from my iPhone >>> >>> On Mar 6, 2012, at 2:49 PM, Rob Scott >> <rsc...@rocketsoftware.com> wrote: >>> >>>>> You have coded "LAE R3,0(R4)" - which is the same as >> "LAE R3,(R4,R0)" >>>> >>>> Should read : >>>> >>>> You have coded "LAE R3,0(R4)" - which is the same as >> "LAE R3,0(R4,R0)" >>>> >>>> Rob Scott >>>> Lead Developer >>>> Rocket Software >>>> 275 Grove Street * Newton, MA 02466-2272 * USA >>>> Tel: +1.781.684.2305 >>>> Email: rsc...@rs.com >>>> Web: www.rocketsoftware.com >>>> >>>> >>>> -----Original Message----- >>>> From: IBM Mainframe Discussion List >> [mailto:IBM-MAIN@bama.ua.edu] On >>>> Behalf Of Rob Scott >>>> Sent: 06 March 2012 19:47 >>>> To: IBM-MAIN@bama.ua.edu >>>> Subject: Re: LAE instruction >>>> >>>> Commas are *very* important in AR-mode >>>> >>>> You have coded "LAE R3,0(R4)" - which is the same as >> "LAE R3,(R4,R0)" >>>> >>>> Coded that way there is no automatic way that AR3 is going >> to inherit the AR4 value. >>>> >>>> You need : "LAE R3,0(,R4)" >>>> >>>> This will ensure that AR3 is populated from the AR for the >> referenced base register R4. >>>> >>>> >>>> Rob Scott >>>> Lead Developer >>>> Rocket Software >>>> 275 Grove Street * Newton, MA 02466-2272 * USA >>>> Tel: +1.781.684.2305 >>>> Email: rsc...@rs.com >>>> Web: www.rocketsoftware.com >>>> >>>> >>>> -----Original Message----- >>>> From: IBM Mainframe Discussion List >> [mailto:IBM-MAIN@bama.ua.edu] On >>>> Behalf Of Micheal Butz >>>> Sent: 06 March 2012 19:05 >>>> To: IBM-MAIN@bama.ua.edu >>>> Subject: LAE instruction >>>> >>>> Hi, >>>> >>>> >>>> >>>> I have two part question regarding the LAE instruction >>>> >>>> >>>> >>>> . What would the sac value e.g. 256,512,768 have >> to be that when >>>> using the LAE instructions with the following operands LAE >> 3,0(R4) >>>> would >>>> AR3 get loaded with AR4 >>>> >>>> >>>> >>>> . Second what value does the displacement play in >> the instruction >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> Thanks >>>> >>>> >>>> >> ---------------------------------------------------------------------- >>>> For IBM-MAIN subscribe / signoff / archive access >> instructions, send >>>> email to lists...@bama.ua.edu with the message: INFO IBM-MAIN >>>> >>>> >> ---------------------------------------------------------------------- >>>> For IBM-MAIN subscribe / signoff / archive access >> instructions, send >>>> email to lists...@bama.ua.edu with the message: INFO IBM-MAIN >>>> >>>> >> ---------------------------------------------------------------------- >>>> For IBM-MAIN subscribe / signoff / archive access >> instructions, send >>>> email to lists...@bama.ua.edu with the message: INFO IBM-MAIN >>> >>> >> ---------------------------------------------------------------------- >>> For IBM-MAIN subscribe / signoff / archive access >> instructions, send email to lists...@bama.ua.edu with the >> message: INFO IBM-MAIN >>> >>> >> ---------------------------------------------------------------------- >>> For IBM-MAIN subscribe / signoff / archive access instructions, send >>> email to lists...@bama.ua.edu with the message: INFO IBM-MAIN >> >> ---------------------------------------------------------------------- >> For IBM-MAIN subscribe / signoff / archive access instructions, send >> email to lists...@bama.ua.edu with the message: INFO IBM-MAIN >> >> > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, send email to > lists...@bama.ua.edu with the message: INFO IBM-MAIN > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, send email to > lists...@bama.ua.edu with the message: INFO IBM-MAIN > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@bama.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: INFO IBM-MAIN
