Type ASSEMBLE
Source Lines : 1,729
Fixes Applied : 6
Most Recent Version : Thursday, December 7, 1978
Last Fix ID : [R13548DK]
Module
DMKVCA
Function
TO SIMULATE THE CHANNEL AND DEVICE OPERATIONS OF THE
CHANNEL-TO-CHANNEL ADAPTER (CTCA) CONNECTED BETWEEN TWO
VIRTUAL MACHINES UNDER VM/370
Attributes
REENTRANT, PAGEABLE, CALLED VIA SVC
Operation
DMKVCAST IS CALLED FROM DMKVIOEX AT THE SAME POINT WHERE
DMKIOSQV IS CALLED FOR NON-SIMULATED DEVICES. AT ENTRY,
DMKVCAST INITIALIZES THE IOBLOK AS DMKIOSQV WOULD, AND
THEN TESTS THE VDEVBLOK TO DETERMINE IF THE VIRTUAL CTCA
IS 'COUPLE'D TO ANOTHER CTCA. IF NOT, DMKDIASM IS CALLED
TO INTERPRET THE CCW STRING AND SIMULATE THE CORRECT
CSW AND SENSE STATUS. IF YES, START I/O SIMULATION
PROCEEDS AS FOLLOWS:
1. THE 'CHXBLOK' AND 'CHYBLOK' ARE REFERENCED THRU THE
X-SIDE AND Y-SIDE VDEVBLOK'S (IN THIS DISCUSSION, THE
X-SIDE IS ALWAYS THE INITIATING CHANNEL).
2. THE FIRST REAL CCW AND THE IOBCAW ARE VALIDATED. IF
ANY ERRORS ARE DETECTED, A CHANNEL PROGRAM CHECK IS
GENERATED AND THE SIMULATION TERMINATES VIA STEP ??
3. THE REAL CCW STRING PRODUCED BY DMKCCWTR IS INTERPRETED
ONE CCW AT A TIME BASED ON THE OPERATION TYPE:
TRANSFER IN CHANNEL: X'08'
IF 'TIC' IS FIRST CCW, GENERATE CHANNEL PROGRAM CHK
IF 'TIC' POINTS TO 'TIC', CAUSE CHANNEL PROGRAM CHK
OTHERWISE, RESTART WITH NEW CCW STRING.
SENSE ADAPTER STATE (EXTENDED MODE ONLY): X'14'
TEST FOR A PREVIOUS Y-SIDE RESET NOT YET CLEARED
AND PRESENT INTERVENTION REQUIRED IF YES.
TEST FOR ATTENTION PENDING FROM Y-SIDE, PRESENT
'ATTN + BUSY' IN INITIAL STATUS IF YES.
OTHERWISE, PRESENT SENSE BYTE ZERO.
IN ALL CASES, SUPPRESS DATA TRANSFER IF 'SKIP' IN CCW.
SENSE COMMAND BYTE: X'04'
EXTENDED MODE: IF PREVIOUS X-SIDE RESET OR HALT I/O
HAS NOT BEEN CLEARED, CLEAR RESET CONDITION,
PRESENT DEVICE END TO Y-SIDE, AND STORE COMMAND
BYTE OF ZERO.
IF PREVIOUS Y-SIDE RESET OR HALT I/O HAS NOT BEEN
CLEARED, PRESENT UNIT CHECK IN INITIAL STATUS.
IF X-SIDE END-OF-FILE LATCH IS SET, RESET LATCH
AND STORE COMMAND BYTE OF ZERO.
OTHERWISE, STORE COMMAND BYTE FROM Y-SIDE ADAPTER
BLOCK. IF THE Y-SIDE COMMAND WAS A CONTROL, PRESENT
DEVICE END TO THE Y-SIDE CHANNEL.
COMPATIBILITY MODE: STORE COMMAND BYTE FROM Y-SIDE
ADAPTER BLOCK. IF THE Y-SIDE COMMAND WAS A CONTROL,
PRESENT DEVICE END TO THE Y-SIDE CHANNEL.
IN ALL CASES, SUPPRESS DATA TRANSFER IF 'SKIP' IN CCW.
EXTENDED-MODE ONLY - WRITE, READ CONTROL:
IF A PREVIOUS X-SIDE HALT I/O OR RESET HAS NOT BEEN
CLEARED, CLEAR THE CONDITION AND PRESENT DEVICE END
TO THE Y-SIDE CHANNEL.
IF A PREVIOUS Y-SIDE HALT I/O OR RESET HAS NOT BEEN
CLEARED, PRESENT UNIT CHECK IN INITIAL STATUS.
OTHERWISE, CONTINUE WITH COMMAND PROCESSING.
CONTROL IMMEDIATE: X'07'
RESET THE X-SIDE END-OF-FILE LATCH IF SET.
IF THE Y-SIDE HAS AN ACTIVE READ, WRITE OR CONTROL
COMMAND, PRESENT 'ATTN + BUSY'.
OTHERWISE, PRESENT ATTENTION TO THE Y-SIDE CHANNEL,
CHANNEL END TO THE X-SIDE CHANNEL, AND WAIT FOR
A 'SENSE COMMAND BYTE' FROM THE Y-SIDE.
DISABLE COMPATIBILITY - MODIFIED NO-OP X'C3':
SET THE INHIBIT COMPATIBILITY LATCH IN THE X-SIDE
ADAPTER BLOCK, INIDCATE THAT BOTH SIDES OF THE
ADAPTER ARE IN EXTENDED MODE, ADVANCE TO NEXT CCW.
ENABLE COMPATIBILITY - MODIFIED NO-OP X'43':
RESET THE X-SIDE INHIBIT COMPATIBILITY LATCH.
IF THE Y-SIDE INHIBIT COMPATIBILITY LATCH IS SET,
LEAVE ADAPTER IN EXTENDED MODE AND ADVANCE TO NEXT
CCW. IF THE Y-SIDE LATCH IS NOT SET, FORCE THE
ADAPTER INTO COMPATIBILITY MODE.
WRITE: X'01'
RESET THE X-SIDE END-OF-FILE LATCH IF SET.
IF THE Y-SIDE HAS AN ACTIVE READ COMMAND, ENTER DATA
TRANSFER MODE.
IF THE Y-SIDE HAS AN ACTIVE WRITE OR CONTROL COMMAND,
PRESENT 'ATTN + BUSY'.
IF THERE IS NO ACTIVE Y-SIDE COMMAND, PRESENT 'ATTN'
TO THE Y-SIDE CHANNEL AND WAIT FOR Y-SIDE ACTIVITY.
WRITE END OF FILE: X'81' (EXTENDED MODE ONLY)
RESET THE X-SIDE END-OF-FILE LATCH IF SET.
IF THE Y-SIDE HAS NO ACTIVE COMMAND, SET THE Y-SIDE
END-OF-FILE LATCH AND CONTINUE PROCESSING.
IF THE Y-SIDE HAS AN ACTIVE READ COMMAND, PRESENT
CHANNEL END, DEVICE END, UNIT EXCEPTION TO THE Y-SIDE.
IF THE Y-SIDE HAS AN ACTIVE CONTROL OR WRITE COMMAND,
PRESENT 'ATTN + BUSY' TO THE X-SIDE CHANNEL.
READ X'02' OR READ BACKWARD X'0C':
EXTENDED MODE: IF THE X-SIDE END-OF-FILE LATCH IS SET,
RESET THE LATCH AND PRESENT UNIT EXCEPTION IN
INITIAL STATUS.
IF THE Y-SIDE HAS AN ACTIVE WRITE COMMAND, ENTER
DATA TRANSFER MODE.
IF THE Y-SIDE HAS AN ACTIVE WRITE OR CONTROL COMMAND,
PRESENT 'ATTN + BUSY'.
IF THERE IS NO ACTIVE Y-SIDE COMMAND, PRESENT 'ATTN'
TO THE Y-SIDE CHANNEL AND WAIT FOR Y-SIDE ACTIVITY.
WHENEVER IT IS NECESSARY TO WAIT FOR ACTIVITY FROM THE
Y-SIDE CHANNEL, A CPEXBLOK IS BUILT AND THE ADDRESS STORED
IN THE CHXBLOK FOR LATER RE-CONNECTION VIA A CALL TO
DMKSTKCP. ANOTHER CPEXBLOK IS BUILT FOR AN EXIT TO THE
CALLING ROUTINE WHILE PRESERVING THE ENTRY SAVE-AREA.
AT APPROPRIATE PLACES DURING COMMAND PROCESSING, A CPEXBLOK
EXIT FOLLOWED BY A CPEXBLOK RESTART IS TAKEN FOR SEQUENCING
CONTROL AND TIMING CONSIDERATIONS.
DATA TRANSFER MODE:
UPON ENTERING DATA TRANSFER MODE, THE FOLLOWING INIT-
IALIZATION STEPS ARE TAKEN:
1. RESET ANY PENDING ATTENTION INTERRUPTS OR FLAGS ON
BOTH THE X-SIDE AND Y-SIDE ADAPTERS.
2. BUILD A CPEXBLOK FOR THE X-SIDE SUCH THAT BOTH X AND Y
ADAPTERS ARE IN A SOFTWARE 'WAIT' STATUS.
3. PRESENT ZERO INITIAL STATUS TO THE X-SIDE CHANNEL.
4. EXCHANGE THE X-SIDE AND Y-SIDE IF NECESSARY SUCH THAT
THE 'READ' OPERATION IS ALWAYS THE X-SIDE ADAPTER.
DATA TRANSFER WILL PROCEED UNINTERRUPTIBLY TO COMPLETION,
IN THE FOLLOWING MANNER:
1. EXAMINE THE Y-SIDE (WRITE) CCW TO DETERMINE THE
MAXIMUM SEGMENT LENGTH FOR DATA TRANSFER.
2. EXAMINE THE X-SIDE (READ) CCW TO DETERMINE ITS
MAXIMUM SEGMENT LENGTH FOR DATA TRANSFER.
3. EXAMINE THE 'CAW' PROTECTION KEY FOR THE READ CCW
AND SIMULATE A PROTECTION CHECK IF IT DOES NOT MATCH
THE REAL STORAGE KEY OF THE READ AREA.
4. COMPARE THE DATA SEGMENT LENGTHS FOR READ AND WRITE.
5. IF THE READ COUNT IS GREATER THAN THE WRITE COUNT,
TRANSFER THE DATA SEGMENT AS SPECIFIED BY THE WRITE
COUNT, AND UPDATE THE WRITE COUNT BY RESTARTING AT
STEP 1. AND SKIPPING STEPS 2. AND 3.
6. IF THE WRITE COUNT IS GREATER THAN THE READ COUNT,
TRANSFER THE DATA SEGMENT AS SPECIFIED BY THE READ
COUNT AND UPDATE THE READ COUNT BY RESTARTING AT STEP
2.
7. IF THE READ COUNT EQUALS THE WRITE COUNT, TRANSFER
THE DATA SEGMENT AND RESTART AT STEP 1.
8. WHEN EITHER THE READ OR WRITE CCW STRING HAS BEEN
EXHAUSTED, DETERMINE IF INCORRECT LENGTH SHOULD BE
INDICATED FOR EITHER OR BOTH CHANNELS AND RE-CONNECT
BOTH SIDES VIA CALLS TO DMKSTKCP.
THE MAXIMUM DATA SEGMENT LENGTH WHICH MAY BE TRANSFERRED
IN A SINGLE STEP IS DETERMINED AS FOLLOWS:
1. NO MORE THAN 2048 BYTES AT ANY TIME - FOR PROTECTION
KEY CHECKING.
2. NO MORE THAN THE LENGTH OF BUFFER FROM THE STARTING
ADDRESS TO THE NEAREST 2048-BYTE STORAGE BOUNDARY.
3. NO MORE THAN THE TOTAL OR REMAINING CCW DATA COUNT.
DATA TRANSFER WILL CONTINUE SO LONG AS THERE IS REMAINING
CCW DATA COUNT OR DATA CHAINED CCW'S. COMMAND CHAINING WILL
STOP DATA TRANSFER IF THE PREVIOUS CCW COUNT IS EXHAUSTED.
READ BACKWARD DATA TRANSFER:
THE READ BACKWARD COMMAND TO A CHANNEL-TO-CHANNEL
ADAPTER RESULTS IN THE DATA BEING INVERTED ON A
CHARACTER BASIS., SINCE THE WRITE-ING CHANNEL IS
SENDING DATA IN FORWARD SEUENCE, BUT THE INDEPENDENT
READ-ING CHANNEL IS READING IN BACKWARD SEQUENCE.
DATA INVERSION IS PERFORMED IN THE FOLLOWING MANNER:
1. IF THE READ BUFFER STARTS AT A 7-BYTE BOUNDARY (I.E. AT
THE LOW-ORDER BYTE OF A DOUBLE WORD), SKIP TO STEP 3.
2. MOVE DATA ONE BYTE AT A TIME UNTIL A 7-BYTE BOUNDARY IS
REACHED, OR THE DATA COUNT IS EXHAUSTED.
3. LOAD INTO A REGISTER PAIR EIGHT BYTES OF WRITE DATA IN
INVERTED ORDER, AND MOVE TO READ BUFFER VIA A DOUBLE-
WORD STORE, UNTIL THE LAST DOUBLE-WORD-ALIGNED DATA HAS
BEEN MOVED.
4. MOVE THE REMAINDER OF THE DATA SEGMENT A SINGLE CHARACTER
AT A TIME UNTIL THE COUNT IS EXHAUSTED.
Calls to Other Routines
DMKFREE - TO OBTAIN FREE STORAGE
DMKFRET - TO RELEASE FREE STORAGE OBTAINED FROM DMKFREE
DMKDIBSM - TO SIMULATE STATUS FOR A NOT READY DEVICE @V407510
DMKSCNVU - TO LOCATE VDEVBLOK, VCUBLOK, VCHBLOK
DMKSTKCP - TO STACK CPEXBLOKS FOR DEFERRED EXECUTION
DMKSTKIO - TO STACK IOBLOKS FOR THE SLIH
DMKTRDSI - TO TRACE SIO'S AND CCW STRINGS TO VIRTUAL CTCA