TOPS-10 Monitor Calls Manual Volume 2 AA-K039D ... - Trailing-Edge

ENQ. [CALLI 151]
22.40 ENQ. [CALLI 151]
FUNCTION
Requests access to resources that are defined by cooperating user
programs. The ENQ. call is one of three monitor calls that provide
control over the ENQ/DEQ facility, which provides resource definition,
control over access to resources, and deadlock detection for ~he
resources. The ENQ/DEQ facility is described in Chapter 8.
CALLING SEQUENCE
MOVE ac, [XWD fcn-code,addr]
ENQ. ac,
error return
skip return
addr:
EXP
XWD
XWD
;header block
In the calling sequence, the program supplies the following variables:
o
o
fcn-code is one of the function codes listed below.
addr is the address of the argument block, which consists of
a header block followed by one or more lock blocks.
The header block contains 1 to 3 words, in the following order:
Offset
o
Symbol
.ENQLL
Contents
The header size, the number of lock requests, and
the total length of the argument, including the
header and all the words in all the lock blocks.
Specifically, the .ENQLL word is formatted as
follows:
Bits
0-5
6-17
18-35
Symbol
EQ.BHS
EQ.LNL
EQ.LLB
Value
Size of the header block. This
value is between 1 and 3, because
the second and third words are
optional. If you omit this
value, the default is 2.
Number of lock blocks following
the header block. Include one
lock block for each resource
requested.
Total length (in words) of the
argument block. All the lock
blocks in a single request must
be the same length. Thus, the
value of EQ.LLB is the header
block length (EQ.BHS) plus the
length of each lock block times
the number of resources requested
(EQ. LNL)
22-109