Optimize matrix scanning (#343)

1 files changed, 6 insertions, 8 deletions

diff --git a/tmk_core/common/bootmagic.c b/tmk_core/common/bootmagic.c
index 2c1b1adfc5..30e8a0f20f 100644
--- a/tmk_core/common/bootmagic.c
+++ b/tmk_core/common/bootmagic.c
@@ -105,15 +105,13 @@ void bootmagic(void)
     }
 }
 
-static bool scan_keycode(uint8_t keycode)
-{
-    for (uint8_t r = 0; r < MATRIX_ROWS; r++) {
+static bool scan_keycode(uint8_t keycode) {
+    for (int8_t r = MATRIX_ROWS - 1; r >= 0; --r) {
         matrix_row_t matrix_row = matrix_get_row(r);
-        for (uint8_t c = 0; c < MATRIX_COLS; c++) {
-            if (matrix_row & ((matrix_row_t)1<<c)) {
-                if (keycode == keymap_key_to_keycode(0, (keypos_t){ .row = r, .col = c })) {
-                    return true;
-                }
+        for (int8_t c = MATRIX_COLS - 1; c >= 0; --c) {
+            if (matrix_row & (matrix_row_t)1 << c) {
+                keypos_t key = (keypos_t){ .row = r, .col = c };
+                if (keycode == keymap_key_to_keycode(0, key)) return true;
             }
         }
     }