Allow arrays of strings to be used with Waveforms

Not an ideal fix, as currently you must specify either `FTVL="STRING"`
or `datatype=numpy.dtype("S40")` during record creation.

This is also untested - specifically I don't know what happens when the
strings are longer than 40 characters

Author: AlexanderWells-diamond

softioc/builder.py

@@ -132,6 +132,8 @@ def Action(name, **fields):
     'uint32':   'ULONG',
     'float32':  'FLOAT',
     'float64':  'DOUBLE',
+    'bytes32':  'STRING',
+    'bytes320': 'STRING',
 }
 
 # Coverts FTVL string to numpy type
@@ -144,6 +146,7 @@ def Action(name, **fields):
     'ULONG':    'uint32',
     'FLOAT':    'float32',
     'DOUBLE':   'float64',
+    'STRING':   'S40',
 }
 
 

softioc/device.py

@@ -391,6 +391,7 @@ def _read_value(self, record):
         return result
 
     def _write_value(self, record, value):
+        value = _require_waveform(value, self._dtype)
         nord = len(value)
         memmove(
             record.BPTR, value.ctypes.data_as(c_void_p),