Remove obsolete workarounds. (SciTools#410)

* Remove obsolete workarounds.

* Remove dead tests.

* Remove more dead tests.

* Remove now-unused workaround routines.

* Review changes.

* Review change: remove another obsolete comment

---------

Co-authored-by: stephenworsley <[email protected]>

iris_grib/_load_convert.py

@@ -225,40 +225,6 @@ def _hindcast_fix(forecast_time):
     return forecast_time
 
 
-def fixup_float32_from_int32(value):
-    """
-    Workaround for use when reading an IEEE 32-bit floating-point value
-    which the ECMWF GRIB API has erroneously treated as a 4-byte signed
-    integer.
-
-    """
-    # Convert from two's complement to sign-and-magnitude.
-    # NB. The bit patterns 0x00000000 and 0x80000000 will both be
-    # returned by the ECMWF GRIB API as an integer 0. Because they
-    # correspond to positive and negative zero respectively it is safe
-    # to treat an integer 0 as a positive zero.
-    if value < 0:
-        value = 0x80000000 - value
-    value_as_uint32 = np.array(value, dtype="u4")
-    value_as_float32 = value_as_uint32.view(dtype="f4")
-    return float(value_as_float32)
-
-
-def fixup_int32_from_uint32(value):
-    """
-    Workaround for use when reading a signed, 4-byte integer which the
-    ECMWF GRIB API has erroneously treated as an unsigned, 4-byte
-    integer.
-
-    NB. This workaround is safe to use with values which are already
-    treated as signed, 4-byte integers.
-
-    """
-    if value >= 0x80000000:
-        value = 0x80000000 - value
-    return value
-
-
 ###############################################################################
 #
 # Identification Section 1
@@ -846,21 +812,16 @@ def grid_definition_template_12(section, metadata):
     lat = section["latitudeOfReferencePoint"] * _GRID_ACCURACY_IN_DEGREES
     lon = section["longitudeOfReferencePoint"] * _GRID_ACCURACY_IN_DEGREES
     scale = section["scaleFactorAtReferencePoint"]
-    # Catch bug in ECMWF GRIB API (present at 1.12.1) where the scale
-    # is treated as a signed, 4-byte integer.
-    if isinstance(scale, int):
-        scale = fixup_float32_from_int32(scale)
     CM_TO_M = 0.01
     easting = section["XR"] * CM_TO_M
     northing = section["YR"] * CM_TO_M
     cs = icoord_systems.TransverseMercator(lat, lon, easting, northing, scale, geog_cs)
 
-    # Deal with bug in ECMWF GRIB API (present at 1.12.1) where these
-    # values are treated as unsigned, 4-byte integers.
-    x1 = fixup_int32_from_uint32(section["X1"])
-    y1 = fixup_int32_from_uint32(section["Y1"])
-    x2 = fixup_int32_from_uint32(section["X2"])
-    y2 = fixup_int32_from_uint32(section["Y2"])
+    # Fetch grid extents
+    x1 = section["X1"]
+    y1 = section["Y1"]
+    x2 = section["X2"]
+    y2 = section["Y2"]
 
     # Rather unhelpfully this grid definition template seems to be
     # overspecified, and thus open to inconsistency. But for determining

iris_grib/_save_rules.py

@@ -48,65 +48,6 @@
 _TIME_RANGE_UNITS_INVERTED = {val: key for key, val in _TIME_RANGE_UNITS.items()}
 
 
-def fixup_float32_as_int32(value):
-    """
-    Workaround for use when the ECMWF GRIB API treats an IEEE 32-bit
-    floating-point value as a signed, 4-byte integer.
-
-    Returns the integer value which will result in the on-disk
-    representation corresponding to the IEEE 32-bit floating-point
-    value.
-
-    """
-    value_as_float32 = np.array(value, dtype="f4")
-    value_as_uint32 = value_as_float32.view(dtype="u4")
-    if value_as_uint32 >= 0x80000000:
-        # Convert from two's-complement to sign-and-magnitude.
-        # NB. Because of the silly representation of negative
-        # integers in GRIB2, there is no value we can pass to
-        # codes_set that will result in the bit pattern 0x80000000.
-        # But since that bit pattern corresponds to a floating
-        # point value of negative-zero, we can safely treat it as
-        # positive-zero instead.
-        value_as_grib_int = 0x80000000 - int(value_as_uint32)
-    else:
-        value_as_grib_int = int(value_as_uint32)
-    return value_as_grib_int
-
-
-def fixup_int32_as_uint32(value):
-    """
-    Workaround for use when the ECMWF GRIB API treats a signed, 4-byte
-    integer value as an unsigned, 4-byte integer.
-
-    Returns the unsigned integer value which will result in the on-disk
-    representation corresponding to the signed, 4-byte integer value.
-
-    """
-    value = int(value)
-    if -0x7FFFFFFF <= value <= 0x7FFFFFFF:
-        if value < 0:
-            # Convert from two's-complement to sign-and-magnitude.
-            value = 0x80000000 - value
-    else:
-        msg = "{} out of range -2147483647 to 2147483647.".format(value)
-        raise ValueError(msg)
-    return value
-
-
-def ensure_set_int32_value(grib, key, value):
-    """
-    Ensure the workaround function :func:`fixup_int32_as_uint32` is applied as
-    necessary to problem keys.
-
-    """
-    try:
-        eccodes.codes_set(grib, key, value)
-    except eccodes.CodesInternalError:
-        value = fixup_int32_as_uint32(value)
-        eccodes.codes_set(grib, key, value)
-
-
 ###############################################################################
 #
 # Constants
@@ -574,14 +515,10 @@ def grid_definition_template_12(cube, grib):
     eccodes.codes_set(grib, "Di", abs(x_step))
     eccodes.codes_set(grib, "Dj", abs(y_step))
     horizontal_grid_common(cube, grib)
-
-    # GRIBAPI expects unsigned ints in X1, X2, Y1, Y2 but it should accept
-    # signed ints, so work around this.
-    # See https://software.ecmwf.int/issues/browse/SUP-1101
-    ensure_set_int32_value(grib, "Y1", int(y_cm[0]))
-    ensure_set_int32_value(grib, "Y2", int(y_cm[-1]))
-    ensure_set_int32_value(grib, "X1", int(x_cm[0]))
-    ensure_set_int32_value(grib, "X2", int(x_cm[-1]))
+    eccodes.codes_set(grib, "Y1", int(y_cm[0]))
+    eccodes.codes_set(grib, "Y2", int(y_cm[-1]))
+    eccodes.codes_set(grib, "X1", int(x_cm[0]))
+    eccodes.codes_set(grib, "X2", int(x_cm[-1]))
 
     # Lat and lon of reference point are measured in millionths of a degree.
     eccodes.codes_set(
@@ -603,14 +540,7 @@ def m_to_cm(value):
     # False easting and false northing are measured in units of (10^-2)m.
     eccodes.codes_set(grib, "XR", m_to_cm(cs.false_easting))
     eccodes.codes_set(grib, "YR", m_to_cm(cs.false_northing))
-
-    # GRIBAPI expects a signed int for scaleFactorAtReferencePoint
-    # but it should accept a float, so work around this.
-    # See https://software.ecmwf.int/issues/browse/SUP-1100
     value = cs.scale_factor_at_central_meridian
-    key_type = eccodes.codes_get_native_type(grib, "scaleFactorAtReferencePoint")
-    if key_type is not float:
-        value = fixup_float32_as_int32(value)
     eccodes.codes_set(grib, "scaleFactorAtReferencePoint", value)
 
 

iris_grib/tests/unit/load_convert/test_grid_definition_template_12.py

@@ -184,17 +184,6 @@ def test_incompatible_grid_extent(self):
         with self.assertRaisesRegex(iris.exceptions.TranslationError, "grid"):
             grid_definition_template_12(section, metadata)
 
-    def test_scale_workaround(self):
-        section = self.section_3()
-        section["scaleFactorAtReferencePoint"] = 1065346526
-        metadata = empty_metadata()
-        grid_definition_template_12(section, metadata)
-        expected = self.expected(0, 1)
-        # A float32 can't hold exactly the same value.
-        cs = expected["dim_coords_and_dims"][0][0].coord_system
-        cs.scale_factor_at_central_meridian = 0.9996012449264526
-        self.assertEqual(metadata, expected)
-
 
 if __name__ == "__main__":
     tests.main()