IBM: HCCW

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.

HCCW

Prolog

Control Block Contents

HCCW DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

HCCW Prolog

 NAME       : HCPHCCW
 DESCRIPTION: HOST CHANNEL CONTROL WORD
 DSECT      : HCCW
 FUNCTION   : PROVIDE SYMOLIC REFERENCES FOR THE FIELDS OF THE FORMAT
              ONE CCWS USED BY CP
 LOCATED BY : N/A
 CREATED BY : N/A
 DELETED BY : N/A

HCCW Control Block Content


HCCW DSECT
Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      HCCW           HOST CHANNEL CONTROL WORD
0000    0 Dbl-Word     8 HCCW1 (0)      AN ENTIRE FORMAT 1 CCW
0000    0 Signed       4 HCCWCFCT (0)   Format 1 CCW first word - cmd,
                                        flag, and count
0000    0 Bitstring    1 HCCWCMND       CCW COMMAND CODE
0001    1 Bitstring    1 HCCWFLAG       CCW FLAG BITS
          1... ....      CCWDC          X'80' CHAIN DATA ADDRESS AND
                                        COUNT
          .1.. ....      CCWCC          X'40' COMMAND CHAIN
          ..1. ....      CCWSILI        X'20' SUPPRESS INCORRECT LENGTH
          ...1 ....      CCWSKIP        X'10' SUPPRESS INBOUND DATA
                                        TRANSFER
          .... 1...      CCWPCIR        X'08' REQUEST PC INTERRUPTION
          .... .1..      CCWIDA         X'04' INDIRECT DATA ADDRESSING
          .... ..11      CCWINVAL       X'03' I/O UNDEFINED PAIR OF BITS
          .... ..1.      CCWSUSPN       X'02' I/O SUSPENSION/RESUMPTION
          .... ...1      CCWUNDEF       X'01' I/O UNDEFINED BIT
0002    2 Signed       2 HCCWCNT        CCW DATA COUNT
0004    4 Address      4 HCCWADDR       CCW DATA ADDRESS
          00000007       HCCWADRX       *-1 CCW FINAL BYTE OF ADDRESS
0008    8 Dbl-Word     8 HCCWNEXT (0)   CCW FOLLOWING CURRENT CCW
          0000000F       HCCWIS         B'1111' ICM/STCM MASK FOR 31 BIT
                                        ADDRESS
          00000004       HCCWMC         04 MVC/CLC LENGTH FOR 31 BIT
                                        ADDRESS
          00000080       HCCWIDAL       B'10000000' IDAL INVALID BIT MASK
          00000008       HCCWLEN        8 LENGTH OF A SINGLE CCW (8
                                        BYTES)

HCCW Storage Layout

*** HCCW - HOST CHANNEL CONTROL WORD
*
*     +------+------+-------------+---------------------------+
*   0 |:WCMND|:WFLAG|  HCCWCNT    |         HCCWADDR          |
*     +------+------+-------------+---------------------------+
*   8 |                                                       |
*     =                       HCCWNEXT                        =
*     |                                                       |
*     +-------------------------------------------------------+
*
*** HCCW - HOST CHANNEL CONTROL WORD