Improve key highlight routine to save a few bytes

xylo.asm

@@ -26,52 +26,49 @@ read_keyboard:
 	jr read_keyboard
 
 key_1:
-	ld c, 0
+	ld e, 0
 	call highlight_key
 	ld a, (counter)
 	call play
-	ld c, 0
-	call highlight_key
-	jr inc_counter
+	ld e, 0
+	jr keyoff
 
 key_2:
-	ld c, 3
+	ld e, 3
 	call highlight_key
 	ld a, (counter)
 	inc a
 	call play
-	ld c, 3
-	call highlight_key
-	jr inc_counter
+	ld e, 3
+	jr keyoff
 
 key_3:
-	ld c, 6
+	ld e, 6
 	call highlight_key
 	ld a, (counter)
 	inc a
 	inc a
 	call play
-	ld c, 6
-	call highlight_key
-	jr inc_counter
+	ld e, 6
+	jr keyoff
 
 key_4:
-	ld c, 9
+	ld e, 9
 	call highlight_key
 	ld a, (counter)
 	add a, 3
 	call play
-	ld c, 9
-	call highlight_key
-	jr inc_counter
+	ld e, 9
+	jr keyoff
 
 key_5:
-	ld c, 12
+	ld e, 12
 	call highlight_key
 	ld a, (counter)
 	add a, 4
 	call play
-	ld c, 12
+	ld e, 12
+keyoff:
 	call highlight_key
 
 inc_counter:
@@ -79,26 +76,25 @@ inc_counter:
 	add a, 5
 	cp 25
 	jr nz, set_counter
-	jp zero_counter
+	jr zero_counter
 
 highlight_key:
 	ld hl, xylo
-	ld b, 0
-	add hl, bc
-	ld d, 15
+	ld d, 0
+	add hl, de
+	ld b, 15
 highlight_row:
-	ld e, 3
+	ld c, 3
 highlight_block:
 	ld a, (hl)
 	xor %01000000
 	ld (hl), a
 	inc hl
-	dec e
+	dec c
 	jr nz, highlight_block
-	ld c, 29
-	add hl, bc
-	dec d
-	jr nz, highlight_row
+	ld e, 29
+	add hl, de
+	djnz highlight_row
 	ret
 
 INCLUDE "sample.asm"