NAME       : HCPPIRBK
 DESCRIPTION: Page Interrupt Return control BlocK.
 DSECT      : PIRBK
 LOCATED BY : FRMBPNT - contained in the FRMTE back pointer if
              the frame is being paged in.
 CREATED BY : HCPGETST ID=PIRBK  (see comments below)
 DELETED BY : HCPRELST ID=PIRBK (see comments below)
 SERIALIZED : PIRBKs are anchored in FRMBPNTG - FRMTE back
              pointer field.  The serialization of the FRMBPNTG
              is a unique thread having access to a unique
              FRMTE chain.
              Updates to fields in the PIRBK are serialized by
              a Test And Set lock: PIRTSLK
 RELOCATION CONSIDERATIONS : None
 COMMENTS   :
              There are two varieties of PIRBK.  Most are gotten  and
              released via HCPGETST and HCPRELST.  However, some of
              the older paging I/O interfaces use the back pointer of
              the FRMTE (FRMBPNTG) as a "short" PIRBK.  This was done
              because they only used the PIRBK for the PIRIRA field.
              Newer interfaces use PIRBKs obtained from Free Storage.

 PIRBK DSECT
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Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      PIRBK          Page Interrupt Return control BlocK.
0000    0 Signed       4 PIRIRA         Interrupt return address for this
                                        block. For input to IRAs, see
                                        HCPPAFIR. nb: IRAs are assumed to
                                        be GOTO, but some are known to be
                                        Call/Return for efficiency.
0004    4 Signed       4 PIROVERLAY (9) Use Dependent Area
0004    4 Signed       4 PIRTOKEN       Used to uniquely identify this
                                        task.
0008    8 Signed       4 PIRCTPAG       Count of pages to process.
000C   12 Signed       4 PIRCTDON       Count of pages processed so far.
0010   16 Dbl-Word     8 *              Reserved for IBM use
0018   24 Dbl-Word     8 *              Reserved for IBM use
0020   32 Dbl-Word     8 *              Reserved for IBM use
0004    4 Signed       4 PIRSAVE1       Miscellaneous save area
0008    8 Signed       4 PIRSAVE2       Miscellaneous Save area
000C   12 Signed       4 PIRSAVE3       Miscellaneous Save area
0010   16 Dbl-Word     8 *              Reserved for IBM use
0018   24 Dbl-Word     8 *              Reserved for IBM use
0020   32 Dbl-Word     8 *              Reserved for IBM use
0004    4 Signed       4 PIRSAVBK       Address of SVGBK for return to
                                        caller
0008    8 Signed       4 PIRFMCT        Count of FRMTEs in Block
000C   12 Signed       4 PIRTOTC        Count of FRMTEs to be returned to
                                        the caller. For non-last-pass
                                        this is only pages that were
                                        successfully read. For last pass
                                        this count includes successfully
                                        read from disk and also pages in
                                        error.
0010   16 Bitstring    1 PIRTSLK        Test And Set lock byte
0011   17 Bitstring    1 *              Reserved for IBM use
0012   18 Signed       2 *              Reserved for IBM use
0014   20 Signed       4 PIRASCBK       ASCBK for the address space of
                                        the FRMTE's using this PIRBK.
                                        This field is used by HCPPAGEW/IE
0018   24 Dbl-Word     8 PIRFMCHN       FRMTE chain anchor
0020   32 Dbl-Word     8 PIRERRFC       Chain of Error FRMTEs. This chain
                                        is used only on the last pass of
                                        an LGR, since pages in error have
                                        their state relocated on the last
                                        pass.
             The following are used to determine the size of the
      this control block.
          00000028       PIRLEN         *-PIRBK Length in bytes.
          00000005       PIRSIZE        (PIRLEN+7)/8 Size in doublewords.

          
*** PIRBK - Page Interrupt Return control BlocK.
*
*     +---------------------------+---------------------------+
*   0 |          PIRIRA           |                           |
*     +---------------------------+                           |
*   8 |                                                       |
*     =                      PIROVERLAY                       =
*     |                                                       |
*     +-------------------------------------------------------+
*  28
*
*** PIRBK - Page Interrupt Return control BlocK.
          
*** Overlay for PIROVERLAY in PIRBK
*
*                                 +---------------------------+
*   0 ...                       4 |         PIRTOKEN          |
*     +---------------------------+---------------------------+
*   8 |         PIRCTPAG          |         PIRCTDON          |
*     +---------------------------+---------------------------+
*  10 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  18 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  20 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  28
*
*** Overlay for PIROVERLAY in PIRBK
          
*** Overlay for PIROVERLAY in PIRBK
*
*                                 +---------------------------+
*   0 ...                       4 |         PIRSAVE1          |
*     +---------------------------+---------------------------+
*   8 |         PIRSAVE2          |         PIRSAVE3          |
*     +---------------------------+---------------------------+
*  10 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  18 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  20 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  28
*
*** Overlay for PIROVERLAY in PIRBK
          
*** Overlay for PIROVERLAY in PIRBK
*
*                                 +---------------------------+
*   0 ...                       4 |         PIRSAVBK          |
*     +---------------------------+---------------------------+
*   8 |         PIRFMCT           |         PIRTOTC           |
*     +------+------+-------------+---------------------------+
*  10 |:TSLK |//////|/////////////|         PIRASCBK          |
*     +------+------+-------------+---------------------------+
*  18 |                       PIRFMCHN                        |
*     +-------------------------------------------------------+
*  20 |                       PIRERRFC                        |
*     +-------------------------------------------------------+
*  28
*
*** Overlay for PIROVERLAY in PIRBK

 
Symbol         Dspl Value
-------------- ---- -----
PIRASCBK       0014
PIRCTDON       000C
PIRCTPAG       0008
PIRERRFC       0020
PIRFMCHN       0018
PIRFMCT        0008
PIRIRA         0000
PIRLEN         0020 00000028
PIROVERLAY     0004
PIRSAVBK       0004
PIRSAVE1       0004
PIRSAVE2       0008
PIRSAVE3       000C
PIRSIZE        0020 00000005
PIRTOKEN       0004
PIRTOTC        000C
PIRTSLK        0010