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Programming Interface Information:
This information is NOT
intended to be
used as Programming Interfaces of VM/ESA. It is to be used for diagnosis only. |
BITMP
Cross Reference (Contains links to field and bit definitions)
BITMP Prolog
NAME : HCPBITMP
DESCRIPTION: Bit Map Control Block
STATUS : VM/ESA Version 2, Release 1.0
DSECT : BITMP
FUNCTION : The Bit Map Control Block contains fields that control
access to the bits, pointers to the bits, and other
useful stuff.
LOCATED BY : R2 at entry to HCPBIT routines points to a full
word that points to the BITMP.
CREATED BY : HCPBIT
DELETED BY : HCPBITRL
REFERENCES : None
SERIALIZED : Changes to the contents of bit maps need not be done
under the control of the BITMP lock, because
Compare-and-Swap is used to change the bits and the
pointers to the bits. However, if serialization is
needed, the users of the bit maps should call the
HCPBIT entry points AS, AX, RS, RX, SX, etc., which
call the analogous HCPLCK entry points for control
over the BITMP lock.
BITMP Control Block Content
BITMP DSECT
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure BITMP Bit Map Control Block This portion of the BITMP is fixed length. The final size of the BITMP depends on how many pointers are actually stored at BITMPPTR. 00000000 BITMPFXD * Fixed portion of the BITMP 0000 0 Dbl-Word 8 BITMPLCK (3) The BITMP lock 0018 24 Signed 4 BITMPMAX The max bit number allowed 001C 28 Signed 4 BITMPPGS How many pointers at BITMPPTR 00000020 BITMPFSZ *-BITMP Size of fixed portion of BITMP expressed in bytes. 0020 32 Address 4 BITMPPTR (0) Start of variable length data. Pointers to pages of bits. The upper bound of the subscript for this array is contained in BITMPPGS.
BITMP Storage Layout
*** BITMP - Bit Map Control Block * * +-------------------------------------------------------+ * 0 | | * = BITMPLCK = * | | * +---------------------------+---------------------------+ * 18 | BITMPMAX | BITMPPGS | * +---------------------------+---------------------------+ * 20 | | * = BITMPPTR = * | | * +-------------------------------------------------------+ * *** BITMP - Bit Map Control Block
BITMP Cross Reference
(contains links to field and bit definitions)Symbol Dspl Value -------------- ---- -----BITMPFSZ 001C 00000020
BITMPFXD 0000 00000000
BITMPLCK 0000
BITMPMAX 0018
BITMPPGS 001C
BITMPPTR 0020
Last updated on 3 Aug 1999 at 11:42:05 EDT.
Copyright IBM Corporation, 1990, 1999