Test subtracting labels

test/asm/label-diff.asm

@@ -0,0 +1,65 @@
+
+PUSHS
+
+SECTION "floating", ROM0
+
+Known: ; This symbol is known to be a label, but its value is not known yet
+	ds 4
+Known2: ; This symbol isn't known either, but the difference is known (4)
+
+SECTION "fixed", ROM0[42]
+
+Constant: ; This label's value is known to be 42
+
+SECTION "fixed 2", ROM0[69]
+
+Constant2: ; Same as above
+
+
+print_diff: MACRO
+	PRINTV (\1) - (\2)
+	PRINTT "\n"
+	PRINTV (\2) - (\1)
+	PRINTT "\n"
+ENDM
+
+POPS ; Ensure we are in neither section
+
+; TODO: uncomment all that can be, there is seriously room for improvement here
+	; Diffing two constants should work
+; But it doesn't yet	print_diff Constant, Constant2
+	; Diffing two labels in the same SECTION as well
+	print_diff Known2, Known
+	; Diffing a constant and a "floating" label cannot work
+; ...And that causes a fatal error	print_diff Constant, Known
+	; Diffing a constant and a ref cannot work
+; ...And that causes a fatal error	print_diff Constant, Unknown
+	; Diffing a floating label and a ref cannot work
+; ...And that causes a fatal error	print_diff Known, Unknown
+
+	; Now let's fiddle with PC
+SECTION "fixed PC", ROM0[420]
+	; Diffing a constant and PC should work
+; But it doesn't yet	print_diff Constant, @
+	; Diffing a floating label and PC cannot work
+; ...And that causes a fatal error	print_diff Known, @
+	; Diffinf a ref and PC cannot work
+; ...And that causes a fatal error	print_diff Unknown, @
+	; Diffing PC and PC should work
+	print_diff @, @
+	; Diffing PC and a label from here should work
+LocalFixed:
+; But it doesn't yet	print_diff LocalFixed, @
+
+SECTION "Floating PC", ROM0
+	; Diffing a constant and PC cannot work
+; ...And that causes a fatal error	print_diff Constant, @
+	; Diffing a floating label and PC cannot work
+; ...And that causes a fatal error	print_diff Known, @
+	; Diffinf a ref and PC cannot work
+; ...And that causes a fatal error	print_diff Unknown, @
+	; Diffing PC and PC should work
+	print_diff @, @
+	; Diffing PC and a label from here should work
+LocalFloating:
+	print_diff LocalFloating, @

test/asm/label-diff.out

@@ -0,0 +1,8 @@
+$4
+$FFFFFFFC
+$0
+$0
+$0
+$0
+$0
+$0