Portability changes
These changes allow state programs to run unchanged on hosts and IOCs.
Replaced VxWorks dependencies with OSI routines
All VxWorks routines have been replaced with the appropriate OSI (Operating System Independent) routines. State programs can run in any environment for which there is an OSI implementation.
Unused (and undocumented)
VX_OPT
option has been removed.
Replaced direct channel access calls with new PV API
All CA calls have been replaced with equivalent calls to a new PV (process variable) API which can be layered on top of not just CA but also other message systems. See See The PV (Process Variable) API.
Added optional generation of main program
The new
+m
(main) option generates a C main program whose single argument is a list of macro assignments.
When this option is enabled, the main thread reads from standard input and can execute
seqShow
,
seqChanShow
etc.
on demand. End of file causes the sequencer to exit.
New Language Features
Entry handler
A one-off
entry
handler can be supplied (
c.f.
the existing
exit
handler). This is called once, at sequencer start-up, in the context of the first state set, before the remaining state set threads have been created. See See entry_handler.
Entry and exit actions
The
entry
block of a state is executed each time the state is entered; the
exit
block is executed each time the state is left. Note that these blocks are aassociated with a state and are not the same as the one-off entry and exit handlers. See See entry_action and See exit_action.
State options
-t
,
-e
and
-x
are now recognized options within the scope of a state.
-t
inhibits the "timer reset" on re-entry to a state from itself;
-e
(for "entry") is used with the new
entry
block, and forces the
entry
statements to be executed on all entries to a state, even if from the same state;
-x
(for "exit") is complementary to
-e
, but for the new
exit
block. See See state_option_stmt.
Queueable monitors
Monitor messages can be queued and then dequeued at leisure. This means that monitor messages are not lost, even when posted rapidly in succession. This feature is supported by new
syncQ
,
pvGetQ
and
pvFreeQ
language elements, and a new
seqQueueShow
routine. When SNL arrays are used, a single queue is shared by the control system variables associated with the elements of the array, which can be useful for parallel control. See See Queuing Monitors and See syncq_stmt.
Device support
An device support module has been added. This allows EPICS records to refererence sequencer internals. At present this is very basic and can only return state-set names. See See Verifying the installation for a well-hidden example (look for "
caget ss0
").
Local variables
SNL does not support the declaration of local variables. However, the C code generated for a
when
clause is now placed within an extra level of braces and the C escape mechanism can be used to declare a local variable. See See Variable Extent.
More functions are safe in action code
In previous versions, some functions,
e.g.
pvPut
, have acquired a resource lock and others,
e.g.
efTestAndClear
, have not. Those that didn't were intended for use in action code and those that did not were intended for use in
when
clauses. This was confusing and dangerous. All such functions now acquire a mutex (that can be taken recursively).
Asynchronous puts
pvPut
can now put process variables asynchronously by using an extra
ASYNC
argument. Completion can be tested using the new
pvPutComplete
. Arrays are supported (so
pvPutComplete
can be used to test whether a set of puts has completed). See See Asynchronous Use of pvPut() and See pvPutComplete.
Synchronous/asynchronous override on gets and puts
pvGet
and
pvPut
both accept an optional
SYNC
or
ASYNC
argument that, for
pvGet
, overrides the default as set using the
-a
option and, for
pvPut
, overrides the default synchronous behavior. See See pvPut and See pvGet.
Sequencer deletion re-written
Sequencer deletion has been completely re-written. You can no longer delete a sequencer by deleting one of its tasks. Instead you must use the new
seqStop
routine. See See Stopping the State Program Tasks.
efClear can wake up state sets
Clearing an event flag can now wake up state sets that reference the event flag in
when
tests.
More C syntax is supported
The "
to
" in
assign
,
sync
and
syncQ
statements is now optional.
Compound expressions such as
i=1,j=2
(often used in
for
loops) are now permitted.
Variables can now be initialized in declarations such as
int i=2;
.
Pre-processor "
#
" lines are now permitted between state sets and states (relaxes restrictions on using
#include
to include code).
"
~
" (complement) and "
^
" (exclusive or) operators are permitted.
ANSI string concatenation,
e.g.
"xxx" "yyy"
is the same as
"xxxyyy"
, is supported.
Full exponential representation is supported for numbers (previously couldn't use "
E
" format).
Bugs fixed
Avoidance of segmentation violations
SEGV no longer occurs if an undeclared variable or event flag is referenced
SEGV no longer occurs if the last bit of an event mask is used
SEGV no longer occurs when doing
seqShow
and there was no previous state
Miscellaneous other problems found by purify were fixed.
Avoidance of race condition which prevented monitors from being enabled
If a connection handler was called before
seq_pvMonitor
, a race condition meant that the
ca_add_array_event
routine might never get called.
Miscellaneous
Compilation warnings have been avoided wherever possible.
A 60Hz system clock frequency is no longer assumed.
Error reporting is now more consistent; it is currently just using
errlogPrintf
.
The new EPICS R3.14
configure
-based make rules are used.
