Allow arrays of strings to be used with Waveforms

Note the tests fail, largely due to now numpy defaults to
a floating point dtype, which we cannot coerce into an array of strings.

Also TODOs need completion...

Author: AlexanderWells-diamond

softioc/builder.py

@@ -147,6 +147,8 @@ def Action(name, **fields):
     'uint32':   'ULONG',
     'float32':  'FLOAT',
     'float64':  'DOUBLE',
+    'bytes32':  'STRING',
+    'bytes320': 'STRING',
 }
 
 # Coverts FTVL string to numpy type
@@ -159,6 +161,7 @@ def Action(name, **fields):
     'ULONG':    'uint32',
     'FLOAT':    'float32',
     'DOUBLE':   'float64',
+    'STRING':   'S40',
 }
 
 
@@ -210,11 +213,15 @@ def _waveform(value, fields):
 
         # Special case for [u]int64: if the initial value comes in as 64 bit
         # integers we cannot represent that, so recast it as [u]int32
+        # Special case for array of strings to correctly identify each element
+        # of the array as a string type.
         if datatype is None:
             if initial_value.dtype == numpy.int64:
                 initial_value = numpy.require(initial_value, numpy.int32)
             elif initial_value.dtype == numpy.uint64:
                 initial_value = numpy.require(initial_value, numpy.uint32)
+            elif initial_value.dtype.char == "S":
+                initial_value = numpy.require(initial_value, numpy.dtype("S40"))
     else:
         initial_value = numpy.array([], dtype = datatype)
         length = _get_length(fields)

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),
@@ -409,6 +410,10 @@ def _value_to_epics(self, value):
         # common class of bug, at the cost of duplicated code and data, here we
         # ensure a copy is taken of the value.
         assert len(value) <= self._nelm, 'Value too long for waveform'
+        # TODO: line below triggers "DeprecationWarning: Applying '+' to a
+        # non-numerical array is ill-defined. Returning a copy, but in the
+        # future this will error."
+        # Probably should change to numpy.copy?
         return +value
 
     def _epics_to_value(self, value):

softioc/fields.py

@@ -146,5 +146,5 @@ def __set_time(self, address, new_time):
         address[0].secs -= EPICS_epoch
 
 
-
+# TODO: DbfCodeToNumpy doesn't exist!
 __all__ = ['RecordFactory', 'DbfCodeToNumpy', 'ca_timestamp']

tests/test_record_values.py

@@ -189,6 +189,24 @@ def record_values_names(fixture_value):
         ),
         numpy.ndarray,
     ),
+    (
+        "wIn_byte_string_array",
+        builder.WaveformIn,
+        [b"AB", b"CD", b"EF"],
+        numpy.array(
+            [b"AB", b"CD", b"EF"], dtype=numpy.dtype("|S40")
+        ),
+        numpy.ndarray,
+    ),
+    (
+        "wOut_byte_string_array",
+        builder.WaveformOut,
+        [b"AB", b"CD", b"EF"],
+        numpy.array(
+            [b"AB", b"CD", b"EF"], dtype=numpy.dtype("|S40")
+        ),
+        numpy.ndarray,
+    ),
     (
         "longStringIn_str",
         builder.longStringIn,