NAME       : HCPHALBK
 DESCRIPTION: Host-ART lookaside block
 DSECT      : HALBK
 FUNCTION   : The HALBK maps ALETs to I-ASITs for
              host-access-register translation.
 SERIALIZED : Each task is responsible for its own
              serialization
 RELOCATION CONSIDERATIONS : None
 COMMENTS   : This block is meant to be used with the
              HCPHALM macro. The user must:
              - acquire HALBK storage
              - have an active HCPUSING on the block
              - fill in the header.
              Then HCPHALM may be used to search and
              manipulate entries in this block.
              The count of the number of entries in the HALBK
              must fit in a fullword; that's the only
              restriction on HALBK size. If, however, the
              total size of the HALBK (header + (entry length
              * number of entries)) could be greater than
              509 doublewords, the PAGES=DECIDE option should
              be used on the HCPGETST and HCPRELST macros.

 HALBK DSECT
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Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      HALBK          Host-ART lookaside block
0000    0 Character   16 HALHDR         HALBK header
0010   16 Character   16 HALENTRY       HALBK entry (there can be more
                                        than one of these).
      Mapping of the HALBK header
0000    0 Signed       4 HALMXENT       Maximum number of HALBK entries
0004    4 Address      4 HALVMDBK       Address of the base VMDBK
                                        associated with the access list
                                        to which the ALETs belong.
0008    8 Character    8 *              Reserved for IBM use.
      Mapping of HALBK entries
0010   16 Bitstring    1 HALSTATE       State flag for the entry
          00000000       HALINVAL       X'00' HALINVAL The entry is
                                        invalid (does not contain an
                                        ALET/i-ASIT pair).
          00000001       HALVALID       X'01' HALVALID The entry is valid
                                        (does contain an ALET/i-ASIT
                                        pair).
0011   17 Bitstring    3 *              Reserved for IBM use
0014   20 Signed       4 HALALET        ALET
0018   24 Character    8 HALIASIT       I-ASIT associated with HALALET
0020   32 Signed       4 HALNEXT (0)    Next entry in the list
      Length equate
          00000004       HALSIZE        (*-HALBK+7)/8 Length of HALBK in
                                        DWs

          
*** HALBK - Host-ART lookaside block
*
*     +-------------------------------------------------------+
*   0 |                        HALHDR                         |
*     |                                                       |
*     +-------------------------------------------------------+
*  10 |                       HALENTRY                        |
*     |                                                       |
*     +-------------------------------------------------------+
*  20
*
*** HALBK - Host-ART lookaside block
          
*** Overlay for HALHDR in HALBK
*
*     +---------------------------+---------------------------+
*   0 |         HALMXENT          |         HALVMDBK          |
*     +---------------------------+---------------------------+
*   8 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  10
*
*** Overlay for HALHDR in HALBK
          
*** Overlay for HALENTRY in HALBK
*
*     +------+--------------------+---------------------------+
*  10 |:STATE|////////////////////|         HALALET           |
*     +------+--------------------+---------------------------+
*  18 |                       HALIASIT                        |
*     +-------------------------------------------------------+
*
*** Overlay for HALENTRY in HALBK

 
Symbol         Dspl Value
-------------- ---- -----
HALALET        0014
HALENTRY       0010
HALHDR         0000
HALIASIT       0018
HALINVAL       0010 00000000
HALMXENT       0000
HALNEXT        0020
HALSIZE        0020 00000004
HALSTATE       0010
HALVALID       0010 00000001
HALVMDBK       0004