Eliminate enum: use const instead, with case-by-case parallel const implementations

macros/const.asm

@@ -0,0 +1,24 @@
+; Enumerate constants
+
+const_def: MACRO
+if _NARG >= 1
+const_value = \1
+else
+const_value = 0
+endc
+if _NARG >= 2
+const_inc = \2
+else
+const_inc = 1
+endc
+ENDM
+
+const: MACRO
+\1 EQU const_value
+const_value = const_value + const_inc
+ENDM
+
+shift_const: MACRO
+\1 EQU (1 << const_value)
+const_value = const_value + const_inc
+ENDM