Programming Interface Information:
This information is NOT intended to be used as Programming Interfaces of z/VM. |
BITMP
Control Block Contents
BITMP DSECT
Cross Reference (Contains links to field and bit definitions)
BITMP Prolog
NAME : HCPBITMP DESCRIPTION: Bit Map Control Block 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 | * +---------------------------+---------------------------+ * *** BITMP - Bit Map Control Block
BITMP Cross Reference
Symbol Dspl Value -------------- ---- ----- BITMPFSZ 001C 00000020 BITMPFXD 0000 00000000 BITMPLCK 0000 BITMPMAX 0018 BITMPPGS 001C BITMPPTR 0020
Copyright IBM Corporation, 1990, 2001