Add a DHGRColours enum mapping the DHGR logical colours to their

(memory-order) 4-bit values.

transcoder/colours.py

@@ -0,0 +1,25 @@
+"""Apple II logical display colours."""
+
+import enum
+
+
+class DHGRColours(enum.Enum):
+    # Value is memory bit order, which is opposite to screen order (bits
+    # ordered Left to Right on screen)
+    BLACK = 0b0000
+    MAGENTA = 0b1000
+    BROWN = 0b0100
+    ORANGE = 0b1100
+    DARK_GREEN = 0b0010
+    GREY1 = 0b1010
+    GREEN = 0b0110
+    YELLOW = 0b1110
+    DARK_BLUE = 0b0001
+    VIOLET = 0b1001
+    GREY2 = 0b0101
+    PINK = 0b1101
+    MED_BLUE = 0b0011
+    LIGHT_BLUE = 0b1011
+    AQUA = 0b0111
+    WHITE = 0b1111
+