add XERState since XER has fields too

diff --git a/src/openpower/xer.py b/src/openpower/xer.py
new file mode 100644 (file)
index 0000000..ac71a70
--- /dev/null
+++ b/src/openpower/xer.py
@@ -0,0 +1,108 @@
+# SPDX-License-Identifier: LGPLv3+
+# Funded by NLnet https://nlnet.nl/
+
+# XXX TODO: get this into openpower/consts.py instead.
+# create the layout from an auto-created Enum XERb
+""" Record for XER as defined in
+Power ISA v3.1B Book I section 3.2.2 page 49(75)
+
+XER fields in MSB0:
+
+| Bits  | Mnemonic | Description      |
+|-------|----------|------------------|
+| 0:31  |     | Reserved         |
+| 32    | SO       | Summary Overflow |
+| 33    | OV       | Overflow         |
+| 34    | CA       | Carry            |
+| 35:43 |     | Reserved         |
+| 44    | OV32     | Overflow32       |
+| 45    | CA32     | Carry32          |
+| 46:56 |     | Reserved         |
+| 57:63 |     | Reserved         |
+"""
+
+from nmigen import Record
+from copy import deepcopy
+from openpower.util import log
+from openpower.decoder.selectable_int import (
+    FieldSelectableInt, SelectableInt)
+
+
+class XERRecord(Record):
+    layout = [("Reserved1", 18),
+              ("CA32", 1),
+              ("OV32", 1),
+              ("Reserved2", 9),
+              ("CA", 1),
+              ("OV", 1),
+              ("SO", 1),
+              ("Reserved3", 32),
+              ]
+
+    def __init__(self, name=None):
+        super().__init__(name=name, layout=XERRecord.layout)
+
+
+class XERState(SelectableInt):
+    def __init__(self, value=0):
+        SelectableInt.__init__(self, value, 64)
+        self.fsi = {}
+        offs = 0
+        # set up sub-fields from Record layout
+        self.fsi = {}
+        l = deepcopy(XERRecord.layout)
+        l.reverse()
+        for field, width in l:
+            end = offs+width
+            fs = tuple(range(offs, end))
+            v = FieldSelectableInt(self, fs)
+            self.fsi[field] = v
+            offs = end
+
+    @property
+    def SO(self):
+        return self.fsi['SO']
+
+    @SO.setter
+    def SO(self, value):
+        self.fsi['SO'].eq(value)
+
+    @property
+    def OV(self):
+        return self.fsi['OV']
+
+    @OV.setter
+    def OV(self, value):
+        self.fsi['OV'].eq(value)
+
+    @property
+    def CA(self):
+        return self.fsi['CA']
+
+    @CA.setter
+    def CA(self, value):
+        self.fsi['CA'].eq(value)
+
+    @property
+    def OV32(self):
+        return self.fsi['OV32']
+
+    @OV32.setter
+    def OV32(self, value):
+        self.fsi['OV32'].eq(value)
+
+    @property
+    def CA32(self):
+        return self.fsi['CA32']
+
+    @CA32.setter
+    def CA32(self, value):
+        self.fsi['CA32'].eq(value)
+
+
+if __name__ == "__main__":
+    from pprint import pprint
+    print("XERRecord.layout:")
+    pprint(XERRecord.layout)
+    print("XERState.fsi:")
+    pprint(XERState().fsi)