Reduce repeated code in key selection routine

xylo.asm

@@ -26,49 +26,30 @@ read_keyboard:
 	jr read_keyboard
 
 key_1:
-	ld e, 0
-	call highlight_key
-	ld a, (counter)
-	call play
-	ld e, 0
-	jr keyoff
+	ld de, 0x0000
+	jr invoke
 
 key_2:
-	ld e, 3
-	call highlight_key
-	ld a, (counter)
-	inc a
-	call play
-	ld e, 3
-	jr keyoff
+	ld de, 0x0103
+	jr invoke
 
 key_3:
-	ld e, 6
-	call highlight_key
-	ld a, (counter)
-	inc a
-	inc a
-	call play
-	ld e, 6
-	jr keyoff
+	ld de, 0x0206
+	jr invoke
 
 key_4:
-	ld e, 9
-	call highlight_key
-	ld a, (counter)
-	add a, 3
-	call play
-	ld e, 9
-	jr keyoff
+	ld de, 0x0309
+	jr invoke
 
 key_5:
-	ld e, 12
+	ld de, 0x040C
+invoke:
+	push de
 	call highlight_key
 	ld a, (counter)
-	add a, 4
+	add a, d
 	call play
-	ld e, 12
-keyoff:
+	pop de
 	call highlight_key
 
 inc_counter:
@@ -80,21 +61,22 @@ inc_counter:
 
 highlight_key:
 	ld hl, xylo
+	push de
 	ld d, 0
 	add hl, de
+	ld e, 30
 	ld b, 15
-highlight_row:
-	ld c, 3
 highlight_block:
 	ld a, (hl)
 	xor %01000000
 	ld (hl), a
 	inc hl
-	dec c
-	jr nz, highlight_block
-	ld e, 29
+	ld (hl), a
+	inc hl
+	ld (hl), a
 	add hl, de
-	djnz highlight_row
+	djnz highlight_block
+	pop de
 	ret
 
 INCLUDE "sample.asm"