[Core] Optimize matrix processing (#7621)

Backport of tmk/tmk_keyboard@ad6059adc7039a54d1db75da783068654906a679

1 files changed, 5 insertions, 4 deletions

diff --git a/tmk_core/common/keyboard.c b/tmk_core/common/keyboard.c
index 125f00ccf..af2b2fd48 100644
--- a/tmk_core/common/keyboard.c
+++ b/tmk_core/common/keyboard.c
@@ -297,13 +297,14 @@ void keyboard_task(void) {
                 }
 #endif
                 if (debug_matrix) matrix_print();
-                for (uint8_t c = 0; c < MATRIX_COLS; c++) {
-                    if (matrix_change & ((matrix_row_t)1 << c)) {
+                matrix_row_t col_mask = 1;
+                for (uint8_t c = 0; c < MATRIX_COLS; c++, col_mask <<= 1) {
+                    if (matrix_change & col_mask) {
                         action_exec((keyevent_t){
-                            .key = (keypos_t){.row = r, .col = c}, .pressed = (matrix_row & ((matrix_row_t)1 << c)), .time = (timer_read() | 1) /* time should not be 0 */
+                            .key = (keypos_t){.row = r, .col = c}, .pressed = (matrix_row & col_mask), .time = (timer_read() | 1) /* time should not be 0 */
                         });
                         // record a processed key
-                        matrix_prev[r] ^= ((matrix_row_t)1 << c);
+                        matrix_prev[r] ^= col_mask;
 #ifdef QMK_KEYS_PER_SCAN
                         // only jump out if we have processed "enough" keys.
                         if (++keys_processed >= QMK_KEYS_PER_SCAN)