Refactor debounce algorithm with static allocation

* Converted arrays to static allocation
* Standardised use of MATRIX_ROWS_PER_HAND for array sizing
* Added Doxygen comments for primary debounce functions
* Removed debounce_free()

quantum/debounce.h

@@ -17,5 +17,3 @@
 bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool changed);
 
 void debounce_init(uint8_t num_rows);
-
-void debounce_free(void);

quantum/debounce/asym_eager_defer_pk.c

@@ -25,7 +25,7 @@ releasing a key, that state is pushed after no changes occur for DEBOUNCE millis
 
 #include "debounce.h"
 #include "timer.h"
-#include <stdlib.h>
+#include "util.h"
 
 #ifdef PROTOCOL_CHIBIOS
 #    if CH_CFG_USE_MEMCORE == FALSE
@@ -49,7 +49,8 @@ typedef struct {
 } debounce_counter_t;
 
 #if DEBOUNCE > 0
-static debounce_counter_t *debounce_counters;
+// Uses MATRIX_ROWS_PER_HAND instead of MATRIX_ROWS to support split keyboards
+static debounce_counter_t debounce_counters[MATRIX_ROWS_PER_HAND * MATRIX_COLS] = {0};
 static fast_timer_t       last_time;
 static bool               counters_need_update;
 static bool               matrix_need_update;
@@ -57,24 +58,10 @@ static bool                cooked_changed;
 
 #    define DEBOUNCE_ELAPSED 0
 
-static void update_debounce_counters_and_transfer_if_expired(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, uint8_t elapsed_time);
+static void update_debounce_counters_and_transfer_if_expired(matrix_row_t raw[], matrix_row_t cooked[], uint8_t elapsed_time);
-static void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows);
+static void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[]);
 
-// we use num_rows rather than MATRIX_ROWS to support split keyboards
+void debounce_init(uint8_t num_rows) {}
-void debounce_init(uint8_t num_rows) {
-    debounce_counters = malloc(num_rows * MATRIX_COLS * sizeof(debounce_counter_t));
-    int i             = 0;
-    for (uint8_t r = 0; r < num_rows; r++) {
-        for (uint8_t c = 0; c < MATRIX_COLS; c++) {
-            debounce_counters[i++].time = DEBOUNCE_ELAPSED;
-        }
-    }
-}
-
-void debounce_free(void) {
-    free(debounce_counters);
-    debounce_counters = NULL;
-}
 
 bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool changed) {
     bool updated_last = false;
@@ -86,12 +73,10 @@ bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool
 
         last_time    = now;
         updated_last = true;
-        if (elapsed_time > UINT8_MAX) {
-            elapsed_time = UINT8_MAX;
-        }
 
         if (elapsed_time > 0) {
-            update_debounce_counters_and_transfer_if_expired(raw, cooked, num_rows, elapsed_time);
+            // Update debounce counters with elapsed timer clamped to UINT8_MAX
+            update_debounce_counters_and_transfer_if_expired(raw, cooked, MIN(elapsed_time, UINT8_MAX));
         }
     }
 
@@ -100,17 +85,28 @@ bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool
             last_time = timer_read_fast();
         }
 
-        transfer_matrix_values(raw, cooked, num_rows);
+        transfer_matrix_values(raw, cooked);
     }
 
     return cooked_changed;
 }
 
-static void update_debounce_counters_and_transfer_if_expired(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, uint8_t elapsed_time) {
+/**
+ * @brief Processes per-key debounce counters and updates the debounced matrix state.
+ *
+ * This function iterates through each key in the matrix and updates its debounce counter
+ * based on the elapsed time. If the debounce period has expired, the debounced state is
+ * updated accordingly for key-down (eager) and key-up (defer) events.
+ *
+ * @param raw The current raw key state matrix.
+ * @param cooked The debounced key state matrix to be updated.
+ * @param elapsed_time The time elapsed since the last debounce update, in milliseconds.
+ */
+static void update_debounce_counters_and_transfer_if_expired(matrix_row_t raw[], matrix_row_t cooked[], uint8_t elapsed_time) {
     counters_need_update = false;
     matrix_need_update   = false;
 
-    for (uint8_t row = 0; row < num_rows; row++) {
+    for (uint8_t row = 0; row < MATRIX_ROWS_PER_HAND; row++) {
         for (uint8_t col = 0; col < MATRIX_COLS; col++) {
             uint16_t index = row * MATRIX_COLS + col;
 
@@ -137,10 +133,21 @@ static void update_debounce_counters_and_transfer_if_expired(matrix_row_t raw[],
     }
 }
 
-static void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows) {
+/**
+ * @brief Applies debounced changes to the matrix state based on per-key counters.
+ *
+ * This function compares the raw and cooked key state matrices to detect changes.
+ * For each key, it updates the debounce counter and the debounced state according
+ * to the debounce algorithm. Key-down events are handled eagerly, while key-up
+ * events are deferred until the debounce period has elapsed.
+ *
+ * @param raw The current raw key state matrix.
+ * @param cooked The debounced key state matrix to be updated.
+ */
+static void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[]) {
     matrix_need_update = false;
 
-    for (uint8_t row = 0; row < num_rows; row++) {
+    for (uint8_t row = 0; row < MATRIX_ROWS_PER_HAND; row++) {
         matrix_row_t delta = raw[row] ^ cooked[row];
         for (uint8_t col = 0; col < MATRIX_COLS; col++) {
             uint16_t index = row * MATRIX_COLS + col;

quantum/debounce/none.c

@@ -32,5 +32,3 @@ bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool
 
     return cooked_changed;
 }
-
-void debounce_free(void) {}

quantum/debounce/sym_defer_g.c

@@ -54,7 +54,6 @@ bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool
     return cooked_changed;
 }
 
-void debounce_free(void) {}
 #else // no debouncing.
 #    include "none.c"
 #endif

quantum/debounce/sym_defer_pk.c

@@ -21,7 +21,7 @@ When no state changes have occured for DEBOUNCE milliseconds, we push the state.
 
 #include "debounce.h"
 #include "timer.h"
-#include <stdlib.h>
+#include "util.h"
 
 #ifdef PROTOCOL_CHIBIOS
 #    if CH_CFG_USE_MEMCORE == FALSE
@@ -42,31 +42,18 @@ When no state changes have occured for DEBOUNCE milliseconds, we push the state.
 typedef uint8_t debounce_counter_t;
 
 #if DEBOUNCE > 0
-static debounce_counter_t *debounce_counters;
+// Uses MATRIX_ROWS_PER_HAND instead of MATRIX_ROWS to support split keyboards
+static debounce_counter_t debounce_counters[MATRIX_ROWS_PER_HAND * MATRIX_COLS] = {0};
 static fast_timer_t       last_time;
 static bool               counters_need_update;
 static bool               cooked_changed;
 
 #    define DEBOUNCE_ELAPSED 0
 
-static void update_debounce_counters_and_transfer_if_expired(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, uint8_t elapsed_time);
+static void update_debounce_counters_and_transfer_if_expired(matrix_row_t raw[], matrix_row_t cooked[], uint8_t elapsed_time);
-static void start_debounce_counters(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows);
+static void start_debounce_counters(matrix_row_t raw[], matrix_row_t cooked[]);
 
-// we use num_rows rather than MATRIX_ROWS to support split keyboards
+void debounce_init(uint8_t num_rows) {}
-void debounce_init(uint8_t num_rows) {
-    debounce_counters = (debounce_counter_t *)malloc(num_rows * MATRIX_COLS * sizeof(debounce_counter_t));
-    int i             = 0;
-    for (uint8_t r = 0; r < num_rows; r++) {
-        for (uint8_t c = 0; c < MATRIX_COLS; c++) {
-            debounce_counters[i++] = DEBOUNCE_ELAPSED;
-        }
-    }
-}
-
-void debounce_free(void) {
-    free(debounce_counters);
-    debounce_counters = NULL;
-}
 
 bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool changed) {
     bool updated_last = false;
@@ -78,12 +65,10 @@ bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool
 
         last_time    = now;
         updated_last = true;
-        if (elapsed_time > UINT8_MAX) {
-            elapsed_time = UINT8_MAX;
-        }
 
         if (elapsed_time > 0) {
-            update_debounce_counters_and_transfer_if_expired(raw, cooked, num_rows, elapsed_time);
+            // Update debounce counters with elapsed timer clamped to UINT8_MAX
+            update_debounce_counters_and_transfer_if_expired(raw, cooked, MIN(elapsed_time, UINT8_MAX));
         }
     }
 
@@ -92,15 +77,26 @@ bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool
             last_time = timer_read_fast();
         }
 
-        start_debounce_counters(raw, cooked, num_rows);
+        start_debounce_counters(raw, cooked);
     }
 
     return cooked_changed;
 }
 
-static void update_debounce_counters_and_transfer_if_expired(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, uint8_t elapsed_time) {
+/**
+ * @brief Updates debounce counters and transfers debounced key states if the debounce period has expired.
+ *
+ * Iterates through each key in the matrix and checks its debounce counter. If the debounce period has expired
+ * for a key, the debounced state is updated to match the raw state. Otherwise, the debounce counter is decremented
+ * by the elapsed time and marked for further updates.
+ *
+ * @param raw The current raw key state matrix.
+ * @param cooked The debounced key state matrix to be updated.
+ * @param elapsed_time The time elapsed since the last debounce update, in milliseconds.
+ */
+static void update_debounce_counters_and_transfer_if_expired(matrix_row_t raw[], matrix_row_t cooked[], uint8_t elapsed_time) {
     counters_need_update = false;
-    for (uint8_t row = 0; row < num_rows; row++) {
+    for (uint8_t row = 0; row < MATRIX_ROWS_PER_HAND; row++) {
         for (uint8_t col = 0; col < MATRIX_COLS; col++) {
             uint16_t index = row * MATRIX_COLS + col;
 
@@ -120,8 +116,18 @@ static void update_debounce_counters_and_transfer_if_expired(matrix_row_t raw[],
     }
 }
 
-static void start_debounce_counters(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows) {
+/**
-    for (uint8_t row = 0; row < num_rows; row++) {
+ * @brief Initializes debounce counters for keys with changed states.
+ *
+ * For each key in the matrix, this function checks if the raw state differs from the debounced state.
+ * If a change is detected and the debounce counter has elapsed, the counter is set to the debounce period
+ * and marked for update. Otherwise, the counter is cleared.
+ *
+ * @param raw The current raw key state matrix.
+ * @param cooked The debounced key state matrix.
+ */
+static void start_debounce_counters(matrix_row_t raw[], matrix_row_t cooked[]) {
+    for (uint8_t row = 0; row < MATRIX_ROWS_PER_HAND; row++) {
         matrix_row_t delta = raw[row] ^ cooked[row];
         for (uint8_t col = 0; col < MATRIX_COLS; col++) {
             uint16_t index = row * MATRIX_COLS + col;

quantum/debounce/sym_defer_pr.c

@@ -19,6 +19,8 @@ DEBOUNCE milliseconds have elapsed since the last change.
 
 #include "debounce.h"
 #include "timer.h"
+#include "util.h"
+#include <string.h>
 
 #ifndef DEBOUNCE
 #    define DEBOUNCE 5
@@ -30,7 +32,10 @@ static uint8_t countdowns[MATRIX_ROWS_PER_HAND] = {0};
 // Last raw state for each matrix row, indexed by row.
 static matrix_row_t last_raw[MATRIX_ROWS_PER_HAND] = {0};
 
-void debounce_init(uint8_t num_rows) {}
+void debounce_init(uint8_t num_rows) {
+    memset(countdowns, 0, sizeof(countdowns));
+    memset(last_raw, 0, sizeof(last_raw));
+}
 
 /**
  * @brief Debounces the raw matrix state and updates the cooked (debounced) state.
@@ -49,7 +54,7 @@ bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool
     uint16_t now           = timer_read();
     uint16_t elapsed16     = TIMER_DIFF_16(now, last_time);
     last_time              = now;
-    uint8_t elapsed        = (elapsed16 > 255) ? 255 : elapsed16;
+    uint8_t elapsed        = MIN(elapsed16, UINT8_MAX);
     bool    cooked_changed = false;
 
     uint8_t* countdown = countdowns;

quantum/debounce/sym_eager_pk.c

@@ -21,7 +21,7 @@ No further inputs are accepted until DEBOUNCE milliseconds have occurred.
 
 #include "debounce.h"
 #include "timer.h"
-#include <stdlib.h>
+#include "util.h"
 
 #ifdef PROTOCOL_CHIBIOS
 #    if CH_CFG_USE_MEMCORE == FALSE
@@ -42,7 +42,8 @@ No further inputs are accepted until DEBOUNCE milliseconds have occurred.
 typedef uint8_t debounce_counter_t;
 
 #if DEBOUNCE > 0
-static debounce_counter_t *debounce_counters;
+// Uses MATRIX_ROWS_PER_HAND instead of MATRIX_ROWS to support split keyboards
+static debounce_counter_t debounce_counters[MATRIX_ROWS_PER_HAND * MATRIX_COLS] = {0};
 static fast_timer_t       last_time;
 static bool               counters_need_update;
 static bool               matrix_need_update;
@@ -50,24 +51,10 @@ static bool                cooked_changed;
 
 #    define DEBOUNCE_ELAPSED 0
 
-static void update_debounce_counters(uint8_t num_rows, uint8_t elapsed_time);
+static void update_debounce_counters(uint8_t elapsed_time);
-static void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows);
+static void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[]);
 
-// we use num_rows rather than MATRIX_ROWS to support split keyboards
+void debounce_init(uint8_t num_rows) {}
-void debounce_init(uint8_t num_rows) {
-    debounce_counters = (debounce_counter_t *)malloc(num_rows * MATRIX_COLS * sizeof(debounce_counter_t));
-    int i             = 0;
-    for (uint8_t r = 0; r < num_rows; r++) {
-        for (uint8_t c = 0; c < MATRIX_COLS; c++) {
-            debounce_counters[i++] = DEBOUNCE_ELAPSED;
-        }
-    }
-}
-
-void debounce_free(void) {
-    free(debounce_counters);
-    debounce_counters = NULL;
-}
 
 bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool changed) {
     bool updated_last = false;
@@ -79,12 +66,10 @@ bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool
 
         last_time    = now;
         updated_last = true;
-        if (elapsed_time > UINT8_MAX) {
-            elapsed_time = UINT8_MAX;
-        }
 
         if (elapsed_time > 0) {
-            update_debounce_counters(num_rows, elapsed_time);
+            // Update debounce counters with elapsed timer clamped to UINT8_MAX
+            update_debounce_counters(MIN(elapsed_time, UINT8_MAX));
         }
     }
 
@@ -93,17 +78,25 @@ bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool
             last_time = timer_read_fast();
         }
 
-        transfer_matrix_values(raw, cooked, num_rows);
+        transfer_matrix_values(raw, cooked);
     }
 
     return cooked_changed;
 }
 
-// If the current time is > debounce counter, set the counter to enable input.
+/**
-static void update_debounce_counters(uint8_t num_rows, uint8_t elapsed_time) {
+ * @brief Updates per-key debounce counters and determines if matrix needs updating.
+ *
+ * Iterates through each key in the matrix and checks its debounce counter.
+ * If the debounce period has elapsed for a key, the counter is reset and the matrix is marked for update.
+ * Otherwise, the counter is decremented by the elapsed time and marked for further updates if needed.
+ *
+ * @param elapsed_time The time elapsed since the last debounce update, in milliseconds.
+ */
+static void update_debounce_counters(uint8_t elapsed_time) {
     counters_need_update = false;
     matrix_need_update   = false;
-    for (uint8_t row = 0; row < num_rows; row++) {
+    for (uint8_t row = 0; row < MATRIX_ROWS_PER_HAND; row++) {
         for (uint8_t col = 0; col < MATRIX_COLS; col++) {
             uint16_t index = row * MATRIX_COLS + col;
 
@@ -120,10 +113,19 @@ static void update_debounce_counters(uint8_t num_rows, uint8_t elapsed_time) {
     }
 }
 
-// upload from raw_matrix to final matrix;
+/**
-static void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows) {
+ * @brief Transfers debounced key states from the raw matrix to the cooked matrix.
+ *
+ * For each key in the matrix, this function checks if its state has changed and if its
+ * debounce counter has elapsed. If so, the debounce counter is reset, the cooked matrix
+ * is updated to reflect the new state, and the matrix is marked for further updates.
+ *
+ * @param raw The current raw key state matrix.
+ * @param cooked The debounced key state matrix to be updated.
+ */
+static void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[]) {
     matrix_need_update = false;
-    for (uint8_t row = 0; row < num_rows; row++) {
+    for (uint8_t row = 0; row < MATRIX_ROWS_PER_HAND; row++) {
         matrix_row_t delta        = raw[row] ^ cooked[row];
         matrix_row_t existing_row = cooked[row];
         for (uint8_t col = 0; col < MATRIX_COLS; col++) {

quantum/debounce/sym_eager_pr.c

@@ -21,7 +21,7 @@ No further inputs are accepted until DEBOUNCE milliseconds have occurred.
 
 #include "debounce.h"
 #include "timer.h"
-#include <stdlib.h>
+#include "util.h"
 
 #ifdef PROTOCOL_CHIBIOS
 #    if CH_CFG_USE_MEMCORE == FALSE
@@ -42,30 +42,19 @@ No further inputs are accepted until DEBOUNCE milliseconds have occurred.
 typedef uint8_t debounce_counter_t;
 
 #if DEBOUNCE > 0
-static bool matrix_need_update;
+// Uses MATRIX_ROWS_PER_HAND instead of MATRIX_ROWS to support split keyboards
-
+static debounce_counter_t debounce_counters[MATRIX_ROWS_PER_HAND] = {0};
-static debounce_counter_t *debounce_counters;
 static fast_timer_t       last_time;
 static bool               counters_need_update;
+static bool               matrix_need_update;
 static bool               cooked_changed;
 
 #    define DEBOUNCE_ELAPSED 0
 
-static void update_debounce_counters(uint8_t num_rows, uint8_t elapsed_time);
+static void update_debounce_counters(uint8_t elapsed_time);
-static void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows);
+static void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[]);
 
-// we use num_rows rather than MATRIX_ROWS to support split keyboards
+void debounce_init(uint8_t num_rows) {}
-void debounce_init(uint8_t num_rows) {
-    debounce_counters = (debounce_counter_t *)malloc(num_rows * sizeof(debounce_counter_t));
-    for (uint8_t r = 0; r < num_rows; r++) {
-        debounce_counters[r] = DEBOUNCE_ELAPSED;
-    }
-}
-
-void debounce_free(void) {
-    free(debounce_counters);
-    debounce_counters = NULL;
-}
 
 bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool changed) {
     bool updated_last = false;
@@ -77,12 +66,10 @@ bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool
 
         last_time    = now;
         updated_last = true;
-        if (elapsed_time > UINT8_MAX) {
-            elapsed_time = UINT8_MAX;
-        }
 
         if (elapsed_time > 0) {
-            update_debounce_counters(num_rows, elapsed_time);
+            // Update debounce counters with elapsed timer clamped to UINT8_MAX
+            update_debounce_counters(MIN(elapsed_time, UINT8_MAX));
         }
     }
 
@@ -91,17 +78,25 @@ bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool
             last_time = timer_read_fast();
         }
 
-        transfer_matrix_values(raw, cooked, num_rows);
+        transfer_matrix_values(raw, cooked);
     }
 
     return cooked_changed;
 }
 
-// If the current time is > debounce counter, set the counter to enable input.
+/**
-static void update_debounce_counters(uint8_t num_rows, uint8_t elapsed_time) {
+ * @brief Updates per-row debounce counters and determines if matrix needs updating.
+ *
+ * Iterates through each row in the matrix and checks its debounce counter. If the debounce
+ * period has elapsed, the counter is reset and the matrix is marked for update. Otherwise,
+ * the counter is decremented by the elapsed time and marked for further updates if needed.
+ *
+ * @param elapsed_time The time elapsed since the last debounce update, in milliseconds.
+ */
+static void update_debounce_counters(uint8_t elapsed_time) {
     counters_need_update = false;
     matrix_need_update   = false;
-    for (uint8_t row = 0; row < num_rows; row++) {
+    for (uint8_t row = 0; row < MATRIX_ROWS_PER_HAND; row++) {
         if (debounce_counters[row] != DEBOUNCE_ELAPSED) {
             if (debounce_counters[row] <= elapsed_time) {
                 debounce_counters[row] = DEBOUNCE_ELAPSED;
@@ -114,10 +109,19 @@ static void update_debounce_counters(uint8_t num_rows, uint8_t elapsed_time) {
     }
 }
 
-// upload from raw_matrix to final matrix;
+/**
-static void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows) {
+ * @brief Transfers debounced key states from the raw matrix to the cooked matrix.
+ *
+ * For each row in the matrix, this function checks if its state has changed and if its
+ * debounce counter has elapsed. If so, the debounce counter is reset, the cooked matrix
+ * is updated to reflect the new state, and the matrix is marked for further updates.
+ *
+ * @param raw The current raw key state matrix.
+ * @param cooked The debounced key state matrix
+ */
+static void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[]) {
     matrix_need_update = false;
-    for (uint8_t row = 0; row < num_rows; row++) {
+    for (uint8_t row = 0; row < MATRIX_ROWS_PER_HAND; row++) {
         matrix_row_t existing_row = cooked[row];
         matrix_row_t raw_row      = raw[row];
 

quantum/debounce/tests/debounce_test_common.cpp

@@ -121,8 +121,6 @@ void DebounceTest::runEventsInternal() {
         checkCookedMatrix(false, "debounce() modified cooked matrix");
         advance_time(1);
     }
-
-    debounce_free();
 }
 
 void DebounceTest::runDebounce(bool changed) {