Custom matrix lite support for split keyboards (#14674)

* Custom matrix lite support for split keyboards

* WIP: matrix -> matrix_common refactor

* Move matrix_post_scan() to matrix_common.c

3 files changed, 72 insertions, 39 deletions

diff --git a/quantum/matrix.c b/quantum/matrix.c
index 483d518ecc..a58cc752fb 100644
--- a/quantum/matrix.c
+++ b/quantum/matrix.c
@@ -63,17 +63,13 @@ extern matrix_row_t matrix[MATRIX_ROWS];      // debounced values
 
 #ifdef SPLIT_KEYBOARD
 // row offsets for each hand
-uint8_t thisHand, thatHand;
+extern uint8_t thisHand, thatHand;
 #endif
 
 // user-defined overridable functions
 __attribute__((weak)) void matrix_init_pins(void);
 __attribute__((weak)) void matrix_read_cols_on_row(matrix_row_t current_matrix[], uint8_t current_row);
 __attribute__((weak)) void matrix_read_rows_on_col(matrix_row_t current_matrix[], uint8_t current_col, matrix_row_t row_shifter);
-#ifdef SPLIT_KEYBOARD
-__attribute__((weak)) void matrix_slave_scan_kb(void) { matrix_slave_scan_user(); }
-__attribute__((weak)) void matrix_slave_scan_user(void) {}
-#endif
 
 static inline void setPinOutput_writeLow(pin_t pin) {
     ATOMIC_BLOCK_FORCEON {
@@ -308,35 +304,6 @@ __attribute__((weak)) bool transport_master_if_connected(matrix_row_t master_mat
     transport_master(master_matrix, slave_matrix);
     return true;  // Treat the transport as always connected
 }
-
-bool matrix_post_scan(void) {
-    bool changed = false;
-    if (is_keyboard_master()) {
-        static bool  last_connected              = false;
-        matrix_row_t slave_matrix[ROWS_PER_HAND] = {0};
-        if (transport_master_if_connected(matrix + thisHand, slave_matrix)) {
-            changed = memcmp(matrix + thatHand, slave_matrix, sizeof(slave_matrix)) != 0;
-
-            last_connected = true;
-        } else if (last_connected) {
-            // reset other half when disconnected
-            memset(slave_matrix, 0, sizeof(slave_matrix));
-            changed = true;
-
-            last_connected = false;
-        }
-
-        if (changed) memcpy(matrix + thatHand, slave_matrix, sizeof(slave_matrix));
-
-        matrix_scan_quantum();
-    } else {
-        transport_slave(matrix + thatHand, matrix + thisHand);
-
-        matrix_slave_scan_kb();
-    }
-
-    return changed;
-}
 #endif
 
 uint8_t matrix_scan(void) {
diff --git a/quantum/matrix.h b/quantum/matrix.h
index 1a3f362fba..d968efeb0f 100644
--- a/quantum/matrix.h
+++ b/quantum/matrix.h
@@ -73,6 +73,7 @@ void matrix_init_user(void);
 void matrix_scan_user(void);
 
 #ifdef SPLIT_KEYBOARD
+bool matrix_post_scan(void);
 void matrix_slave_scan_kb(void);
 void matrix_slave_scan_user(void);
 #endif
diff --git a/quantum/matrix_common.c b/quantum/matrix_common.c
index fe1d5b1edd..79f77421e1 100644
--- a/quantum/matrix_common.c
+++ b/quantum/matrix_common.c
@@ -4,6 +4,14 @@
 #include "wait.h"
 #include "print.h"
 #include "debug.h"
+#ifdef SPLIT_KEYBOARD
+#    include "split_common/split_util.h"
+#    include "split_common/transactions.h"
+
+#    define ROWS_PER_HAND (MATRIX_ROWS / 2)
+#else
+#    define ROWS_PER_HAND (MATRIX_ROWS)
+#endif
 
 #ifndef MATRIX_IO_DELAY
 #    define MATRIX_IO_DELAY 30
@@ -13,6 +21,11 @@
 matrix_row_t raw_matrix[MATRIX_ROWS];
 matrix_row_t matrix[MATRIX_ROWS];
 
+#ifdef SPLIT_KEYBOARD
+// row offsets for each hand
+uint8_t thisHand, thatHand;
+#endif
+
 #ifdef MATRIX_MASKED
 extern const matrix_row_t matrix_mask[];
 #endif
@@ -78,18 +91,61 @@ uint8_t matrix_key_count(void) {
     return count;
 }
 
+#ifdef SPLIT_KEYBOARD
+bool matrix_post_scan(void) {
+    bool changed = false;
+    if (is_keyboard_master()) {
+        matrix_row_t slave_matrix[ROWS_PER_HAND] = {0};
+        if (transport_master_if_connected(matrix + thisHand, slave_matrix)) {
+            for (int i = 0; i < ROWS_PER_HAND; ++i) {
+                if (matrix[thatHand + i] != slave_matrix[i]) {
+                    matrix[thatHand + i] = slave_matrix[i];
+                    changed              = true;
+                }
+            }
+        } else {
+            // reset other half if disconnected
+            for (int i = 0; i < ROWS_PER_HAND; ++i) {
+                matrix[thatHand + i] = 0;
+                slave_matrix[i]      = 0;
+            }
+
+            changed = true;
+        }
+
+        matrix_scan_quantum();
+    } else {
+        transport_slave(matrix + thatHand, matrix + thisHand);
+
+        matrix_slave_scan_kb();
+    }
+
+    return changed;
+}
+#endif
+
 /*　`matrix_io_delay ()` exists for backwards compatibility. From now on, use matrix_output_unselect_delay().　*/
 __attribute__((weak)) void matrix_io_delay(void) { wait_us(MATRIX_IO_DELAY); }
-
 __attribute__((weak)) void matrix_output_select_delay(void) { waitInputPinDelay(); }
 __attribute__((weak)) void matrix_output_unselect_delay(uint8_t line, bool key_pressed) { matrix_io_delay(); }
 
 // CUSTOM MATRIX 'LITE'
 __attribute__((weak)) void matrix_init_custom(void) {}
-
 __attribute__((weak)) bool matrix_scan_custom(matrix_row_t current_matrix[]) { return true; }
 
+#ifdef SPLIT_KEYBOARD
+__attribute__((weak)) void matrix_slave_scan_kb(void) { matrix_slave_scan_user(); }
+__attribute__((weak)) void matrix_slave_scan_user(void) {}
+#endif
+
 __attribute__((weak)) void matrix_init(void) {
+#ifdef SPLIT_KEYBOARD
+    split_pre_init();
+
+    thisHand = isLeftHand ? 0 : (ROWS_PER_HAND);
+    thatHand = ROWS_PER_HAND - thisHand;
+#endif
+
     matrix_init_custom();
 
     // initialize matrix state: all keys off
@@ -98,17 +154,26 @@ __attribute__((weak)) void matrix_init(void) {
         matrix[i]     = 0;
     }
 
-    debounce_init(MATRIX_ROWS);
+    debounce_init(ROWS_PER_HAND);
 
     matrix_init_quantum();
+
+#ifdef SPLIT_KEYBOARD
+    split_post_init();
+#endif
 }
 
 __attribute__((weak)) uint8_t matrix_scan(void) {
     bool changed = matrix_scan_custom(raw_matrix);
 
-    debounce(raw_matrix, matrix, MATRIX_ROWS, changed);
-
+#ifdef SPLIT_KEYBOARD
+    debounce(raw_matrix, matrix + thisHand, ROWS_PER_HAND, changed);
+    changed = (changed || matrix_post_scan());
+#else
+    debounce(raw_matrix, matrix, ROWS_PER_HAND, changed);
     matrix_scan_quantum();
+#endif
+
     return changed;
 }