osk: wrap the cursor around all four edges

Left at column 0 wraps to the last column (and vice-versa); up at the top
row wraps to the bottom (and vice-versa). Makes reaching far keys quicker
- e.g. the Enter/space area is one UP away from the top row.

1 files changed, 27 insertions, 19 deletions

diff --git a/src/osk.asm b/src/osk.asm
index b8ee611..490a402 100644
--- a/src/osk.asm
+++ b/src/osk.asm
@@ -246,38 +246,46 @@ osk_toggle::
     ld [rLCDC], a
     ret
 
-; movement (with clamping); each moves the highlight
+; movement with wrap-around; each moves the highlight
 osk_up:
+    call osk_unhighlight
     ld a, [wOskRow]
     or a
-    ret z
-    call osk_unhighlight
-    ld hl, wOskRow
-    dec [hl]
+    jr nz, .d
+    ld a, OSK_ROWS              ; 0 -> ROWS, so dec wraps to ROWS-1
+.d
+    dec a
+    ld [wOskRow], a
     jr osk_highlight
 osk_down:
-    ld a, [wOskRow]
-    cp OSK_ROWS-1
-    ret z
     call osk_unhighlight
-    ld hl, wOskRow
-    inc [hl]
+    ld a, [wOskRow]
+    inc a
+    cp OSK_ROWS
+    jr c, .s
+    xor a                      ; past bottom -> wrap to 0
+.s
+    ld [wOskRow], a
     jr osk_highlight
 osk_left:
+    call osk_unhighlight
     ld a, [wOskCol]
     or a
-    ret z
-    call osk_unhighlight
-    ld hl, wOskCol
-    dec [hl]
+    jr nz, .d
+    ld a, OSK_COLS
+.d
+    dec a
+    ld [wOskCol], a
     jr osk_highlight
 osk_right:
-    ld a, [wOskCol]
-    cp OSK_COLS-1
-    ret z
     call osk_unhighlight
-    ld hl, wOskCol
-    inc [hl]
+    ld a, [wOskCol]
+    inc a
+    cp OSK_COLS
+    jr c, .s
+    xor a
+.s
+    ld [wOskCol], a
     jr osk_highlight
 
 ; -> A = type value of the selected key