Remove option of specifying scalar value for mbbi and mbbo records

At the same time, remove all reference to RVAL fields by instead using
EPICS NO_CONVERT return codes as appropriate.  This style of processing
is the same as that done for epics_device.

Author: Araneidae

docs/reference/api.rst

@@ -263,18 +263,25 @@ All functions return a wrapped `ProcessDeviceSupportIn` or
     Create ``stringin`` and ``stringout`` records.
 
 ..  function::
-        mbbIn(name, *option_values, **fields)
-        mbbOut(name, *option_values, **fields)
+        mbbIn(name, *options, **fields)
+        mbbOut(name, *options, **fields)
 
     Create ``mbbi`` and ``mbbo`` records.  Up to 16 options can be specified as
-    a list of two or three field tuples.  The first field of each tuple is the
-    option name, the second field is the option value, and the third optional
-    field is the option severity.  For example::
+    either an option name or a tuple of tw fields.  The name or first field of
+    the tuple names the option, and the second optional field is the option
+    severity.  For example::
 
         status = mbbIn('STATUS',
-            ('OK', 0),
-            ('FAILING', 1, alarm.MINOR_ALARM),
-            ('FAILED', 2, alarm.MAJOR_ALARM))
+            'OK',
+            ('FAILING', alarm.MINOR_ALARM),
+            ('FAILED', alarm.MAJOR_ALARM))
+
+    Numerical values are assigned to options sequentially from 0 to 15 and
+    cannot be overridden.
+
+    ..  warning::
+        This is a strictly incompatible change from version 2, but is now
+        compatible with version 2 of epics_device_.
 
 ..  function::
         Waveform(name, [value,] **fields)
@@ -518,3 +525,5 @@ Working with OUT records
     ..  method:: get()
 
         Returns the value associated with the record.
+
+.. _epics_device: https://github.com/Araneidae/epics_device

softioc/builder.py

@@ -63,31 +63,30 @@ def longOut(name, DRVL=None, DRVH=None, EGU=None, **fields):
     'ZR', 'ON', 'TW', 'TH', 'FR', 'FV', 'SX', 'SV',     # 0-7
     'EI', 'NI', 'TE', 'EL', 'TV', 'TT', 'FT', 'FF']     # 8-15
 
-# Adds a list of (option, value [,severity]) tuples into field settings
+# Converts a list of (option [,severity]) values or tuples into field settings
 # suitable for mbbi and mbbo records.
-def _process_mbb_values(option_values, fields):
-    def process_value(prefix, option, value, severity=None):
+def _process_mbb_values(options, fields):
+    def process_value(prefix, value, option, severity=None):
         fields[prefix + 'ST'] = option
         fields[prefix + 'VL'] = value
         if severity:
             fields[prefix + 'SV'] = severity
-    for default_value, (prefix, value) in \
-            enumerate(zip(_mbbPrefixes, option_values)):
-        if isinstance(value, str):
-            # The value is a simple string naming the option.  Assign a
-            # default numerical value (and no severity setting).
-            process_value(prefix, value, default_value)
+    for prefix, (value, option) in zip(_mbbPrefixes, enumerate(options)):
+        if isinstance(value, tuple):
+            # The option is tuple consisting of the option name and an optional
+            # alarm severity.
+            process_value(prefix, value, *option)
         else:
-            # The value is two- or three-tuple consisting of an option name, a
-            # corresponding numerical value and an alarm severity.
-            process_value(prefix, *value)
+            # The option is a simple string naming the option.  Assign the
+            # default numerical value (and no severity setting).
+            process_value(prefix, value, option)
 
-def mbbIn(name, *option_values, **fields):
-    _process_mbb_values(option_values, fields)
+def mbbIn(name, *options, **fields):
+    _process_mbb_values(options, fields)
     return _in_record('mbbi', name, **fields)
 
-def mbbOut(name, *option_values, **fields):
-    _process_mbb_values(option_values, fields)
+def mbbOut(name, *options, **fields):
+    _process_mbb_values(options, fields)
     return PythonDevice.mbbo(name, OMSL = 'supervisory', **fields)
 
 

softioc/device.py

@@ -15,6 +15,12 @@
 dispatcher = None
 
 
+# EPICS processing return codes
+EPICS_OK = 0
+EPICS_ERROR = 1
+NO_CONVERT = 2
+
+
 class ProcessDeviceSupportCore(DeviceSupportCore, RecordLookup):
     '''Implements canonical default processing for records with a _process
     method.  Processing typically either copies a locally set value into the
@@ -25,11 +31,15 @@ class ProcessDeviceSupportCore(DeviceSupportCore, RecordLookup):
     # will have to override this to also add their special_linconv method.
     _dset_extra_ = ([('process', CFUNCTYPE(c_int, c_void_p))], [0])
 
+    # For some record types we want to return a different return code either
+    # from record init or processing
+    _epics_rc = EPICS_OK
+
     # Default implementations of read and write, overwritten where necessary.
     def _read_value(self, record):
-        return getattr(record, self._val_field_)
+        return getattr(record, 'VAL')
     def _write_value(self, record, value):
-        setattr(record, self._val_field_, value)
+        setattr(record, 'VAL', value)
 
 
 class ProcessDeviceSupportIn(ProcessDeviceSupportCore):
@@ -59,7 +69,7 @@ def _process(self, record, _value=None):
         self.process_severity(record, severity, alarm)
         if timestamp is not None:
             record.TIME = timestamp
-        return 0
+        return self._epics_rc
 
     def set(self, value,
             severity=alarm.NO_ALARM, alarm=alarm.UDF_ALARM, timestamp=None):
@@ -112,28 +122,28 @@ def init_record(self, record):
             record.TIME = time.time()
             record.UDF = 0
             recGblResetAlarms(record)
-        return self.__super.init_record(record)
+        return self._epics_rc
 
     def _process(self, record):
         '''Processing suitable for output records.  Performs immediate value
         validation and asynchronous update notification.'''
         value = self._read_value(record)
         if numpy.all(value == self._value) and not self.__always_update:
             # If the value isn't making a change then don't do anything.
-            return 0
+            return EPICS_OK
         if self.__enable_write and self.__validate and \
                 not self.__validate(self, value):
             # Asynchronous validation rejects value.  It's up to the
             # validation routine to do any logging.  In this case restore the
             # last good value.
             if self._value is not None:
                 self._write_value(record, self._value)
-            return 1
+            return EPICS_ERROR
 
         self._value = value
         if self.__on_update and self.__enable_write:
             dispatcher(self.__on_update, value)
-        return 0
+        return EPICS_OK
 
 
     NumpyCharCodeToDbr = {
@@ -209,16 +219,14 @@ def get(self):
         return self._value
 
 
-def _Device(Base, record_type, rval=False, mlst=False, default=0):
+def _Device(Base, record_type, mlst=False, default=0, convert=True):
     '''Wrapper for generating simple records.'''
-    val_field = 'RVAL' if rval else 'VAL'
-
     class GenericDevice(Base):
         _record_type_ = record_type
         _device_name_ = 'devPython_' + record_type
-        _val_field_ = val_field
         _default_ = default
-        _fields_ = ['UDF', val_field]
+        _fields_ = ['UDF', 'VAL']
+        _epics_rc = EPICS_OK if convert else NO_CONVERT
         if mlst:
             _fields_.append('MLST')
 
@@ -231,21 +239,19 @@ class GenericDevice(Base):
 def _Device_In(type, **kargs):
     return _Device(_In,  type, **kargs)
 
-def _Device_Out(type, rval=False, mlst=True):
-    return _Device(_Out, type, rval=rval, mlst=mlst, default=None)
+def _Device_Out(type, convert=True, mlst=True):
+    return _Device(_Out, type, convert=convert, mlst=mlst, default=None)
 
 longin = _Device_In('longin')
 longout = _Device_Out('longout')
-bi = _Device_In('bi', rval=True)
-bo = _Device_Out('bo', rval=True)
+bi = _Device_In('bi', convert=False)
+bo = _Device_Out('bo', convert=False)
 stringin = _Device_In('stringin', mlst=False, default='')
 stringout = _Device_Out('stringout', mlst=False)
-mbbi = _Device_In('mbbi', rval=True)
-mbbo = _Device_Out('mbbo', rval=True)
+mbbi = _Device_In('mbbi', convert=False)
+mbbo = _Device_Out('mbbo', convert=False)
 
 
-NO_CONVERT = 2
-
 dset_process_linconv = (
     [('process',         CFUNCTYPE(c_int, c_void_p)),
      ('special_linconv', CFUNCTYPE(c_int, c_void_p, c_int))],
@@ -257,10 +263,10 @@ def _Device_Out(type, rval=False, mlst=True):
 class ai(ProcessDeviceSupportIn):
     _record_type_ = 'ai'
     _device_name_ = 'devPython_ai'
-    _val_field_ = 'VAL'
     _default_ = 0.0
     _fields_ = ['UDF', 'VAL']
     _dset_extra_ = dset_process_linconv
+    _epics_rc = NO_CONVERT
 
     def _process(self, record):
         _value = self._value
@@ -270,17 +276,12 @@ def _process(self, record):
         record.UDF = int(numpy.isnan(_value[0]))
         return NO_CONVERT
 
-
 class ao(ProcessDeviceSupportOut):
     _record_type_ = 'ao'
     _device_name_ = 'devPython_ao'
-    _val_field_ = 'VAL'
     _fields_ = ['UDF', 'VAL', 'MLST']
     _dset_extra_ = dset_process_linconv
-
-    def init_record(self, record):
-        self.__super.init_record(record)
-        return NO_CONVERT
+    _epics_rc = NO_CONVERT