Unify fields in ISA description in thingamajig_disasm.py

thingamajig_disasm.py

@@ -1,29 +1,33 @@
 #!/usr/bin/env python
 from collections import namedtuple
+import enum
 
-Opcode = namedtuple('Opcode', ('mnemonic', 'rx', 'ry', 'addr', 'immediate'))
+class rfield(enum.Enum):
+	none, reg, imm_flag = range(3)
+
+Opcode = namedtuple('Opcode', ('mnemonic', 'rx', 'ry', 'addr'))
 
 opcodes = [
-	Opcode('halt', rx=False, ry=False, addr=False, immediate=False),
-	Opcode('ret', rx=False, ry=False, addr=False, immediate=False),
-
-	Opcode('shl', rx=True, ry=False, addr=False, immediate=False),
-	Opcode('shr', rx=True, ry=False, addr=False, immediate=False),
-	Opcode('rol', rx=True, ry=False, addr=False, immediate=False),
-	Opcode('ror', rx=True, ry=False, addr=False, immediate=False),
-
-	Opcode('nand', rx=True, ry=True, addr=False, immediate=False),
-	Opcode('and', rx=True, ry=True, addr=False, immediate=False),
-	Opcode('or', rx=True, ry=True, addr=False, immediate=False),
-	Opcode('xor', rx=True, ry=True, addr=False, immediate=False),
-
-	Opcode('load', rx=True, ry=False, addr=True, immediate=True),
-	Opcode('store', rx=False, ry=True, addr=True, immediate=False),
-
-	Opcode('breq', rx=True, ry=True, addr=True, immediate=False),
-	Opcode('brneq', rx=True, ry=True, addr=True, immediate=False),
-	Opcode('cleq', rx=True, ry=True, addr=True, immediate=False),
-	Opcode('clneq', rx=True, ry=True, addr=True, immediate=False),
+	Opcode('halt', rx=rfield.none, ry=rfield.none, addr=False),
+	Opcode('ret', rx=rfield.none, ry=rfield.none, addr=False),
+
+	Opcode('shl', rx=rfield.reg, ry=rfield.none, addr=False),
+	Opcode('shr', rx=rfield.reg, ry=rfield.none, addr=False),
+	Opcode('rol', rx=rfield.reg, ry=rfield.none, addr=False),
+	Opcode('ror', rx=rfield.reg, ry=rfield.none, addr=False),
+
+	Opcode('nand', rx=rfield.reg, ry=rfield.reg, addr=False),
+	Opcode('and', rx=rfield.reg, ry=rfield.reg, addr=False),
+	Opcode('or', rx=rfield.reg, ry=rfield.reg, addr=False),
+	Opcode('xor', rx=rfield.reg, ry=rfield.reg, addr=False),
+
+	Opcode('load', rx=rfield.reg, ry=rfield.imm_flag, addr=True),
+	Opcode('store', rx=rfield.none, ry=rfield.reg, addr=True),
+
+	Opcode('breq', rx=rfield.reg, ry=rfield.reg, addr=True),
+	Opcode('brneq', rx=rfield.reg, ry=rfield.reg, addr=True),
+	Opcode('cleq', rx=rfield.reg, ry=rfield.reg, addr=True),
+	Opcode('clneq', rx=rfield.reg, ry=rfield.reg, addr=True),
 ]
 
 Instruction = namedtuple('Instruction', ['opcode', 'rx', 'ry', 'addr', 'immediate'])
@@ -42,11 +46,12 @@ def segment(binary, origin):
 		rx = (byte >> 2) & 3
 		ry = byte & 3
 
-		immediate = opcodes[opcode].immediate and ry == 3
+		immediate = opcodes[opcode].ry == rfield.imm_flag and ry == 3
 
 		valid = True
-		if not opcodes[opcode].rx and rx != 0: valid = False
-		if not opcodes[opcode].ry and not immediate and ry != 0: valid = False
+		if opcodes[opcode].rx == rfield.none and rx != 0: valid = False
+		if opcodes[opcode].ry == rfield.none and ry != 0: valid = False
+		if opcodes[opcode].ry == rfield.imm_flag and ry not in (0, 3): valid = False
 		if opcodes[opcode].addr and not immediate and ip + 2 >= len(binary): valid = False
 		if immediate and ip + 1 >= len(binary): valid = False
 
@@ -80,9 +85,9 @@ def disasm(binary, origin = 0):
 		else:
 			mnemonic = opcodes[contents.opcode].mnemonic
 			fields = []
-			if opcodes[contents.opcode].rx:
+			if opcodes[contents.opcode].rx == rfield.reg:
 				fields.append(f'r{contents.rx}')
-			if opcodes[contents.opcode].ry:
+			if opcodes[contents.opcode].ry == rfield.reg:
 				fields.append(f'r{contents.ry}')
 			if contents.immediate is not None:
 				fields.append(f'#{contents.immediate:02x}')