quantum/debounce: rename debouncing algorithms (#9564)

* quantum/debounce: rename debouncing algorithms according to Issue 8763

This is the second attempt at implementation, with no ts_ and cy_ prefixes, since those will be implemented with macros.

* Debouncing documentation: Refactor, add some generic info, and merge into a single document

1 files changed, 110 insertions, 0 deletions

diff --git a/quantum/debounce/sym_eager_pr.c b/quantum/debounce/sym_eager_pr.c
new file mode 100644
index 0000000000..d12931fddb
--- /dev/null
+++ b/quantum/debounce/sym_eager_pr.c
@@ -0,0 +1,110 @@
+/*
+Copyright 2019 Alex Ong<the.onga@gmail.com>
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 2 of the License, or
+(at your option) any later version.
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/*
+Basic per-row algorithm. Uses an 8-bit counter per row.
+After pressing a key, it immediately changes state, and sets a counter.
+No further inputs are accepted until DEBOUNCE milliseconds have occurred.
+*/
+
+#include "matrix.h"
+#include "timer.h"
+#include "quantum.h"
+#include <stdlib.h>
+
+#ifndef DEBOUNCE
+#    define DEBOUNCE 5
+#endif
+
+#define debounce_counter_t uint8_t
+static bool matrix_need_update;
+
+static debounce_counter_t *debounce_counters;
+static bool                counters_need_update;
+
+#define DEBOUNCE_ELAPSED 251
+#define MAX_DEBOUNCE (DEBOUNCE_ELAPSED - 1)
+
+static uint8_t wrapping_timer_read(void) {
+    static uint16_t time        = 0;
+    static uint8_t  last_result = 0;
+    uint16_t        new_time    = timer_read();
+    uint16_t        diff        = new_time - time;
+    time                        = new_time;
+    last_result                 = (last_result + diff) % (MAX_DEBOUNCE + 1);
+    return last_result;
+}
+
+void update_debounce_counters(uint8_t num_rows, uint8_t current_time);
+void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, uint8_t current_time);
+
+// we use num_rows rather than MATRIX_ROWS to support split keyboards
+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(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool changed) {
+    uint8_t current_time  = wrapping_timer_read();
+    bool    needed_update = counters_need_update;
+    if (counters_need_update) {
+        update_debounce_counters(num_rows, current_time);
+    }
+
+    if (changed || (needed_update && !counters_need_update) || matrix_need_update) {
+        transfer_matrix_values(raw, cooked, num_rows, current_time);
+    }
+}
+
+// If the current time is > debounce counter, set the counter to enable input.
+void update_debounce_counters(uint8_t num_rows, uint8_t current_time) {
+    counters_need_update                 = false;
+    debounce_counter_t *debounce_pointer = debounce_counters;
+    for (uint8_t row = 0; row < num_rows; row++) {
+        if (*debounce_pointer != DEBOUNCE_ELAPSED) {
+            if (TIMER_DIFF(current_time, *debounce_pointer, MAX_DEBOUNCE) >= DEBOUNCE) {
+                *debounce_pointer = DEBOUNCE_ELAPSED;
+            } else {
+                counters_need_update = true;
+            }
+        }
+        debounce_pointer++;
+    }
+}
+
+// upload from raw_matrix to final matrix;
+void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, uint8_t current_time) {
+    matrix_need_update                   = false;
+    debounce_counter_t *debounce_pointer = debounce_counters;
+    for (uint8_t row = 0; row < num_rows; row++) {
+        matrix_row_t existing_row = cooked[row];
+        matrix_row_t raw_row      = raw[row];
+
+        // determine new value basd on debounce pointer + raw value
+        if (existing_row != raw_row) {
+            if (*debounce_pointer == DEBOUNCE_ELAPSED) {
+                *debounce_pointer    = current_time;
+                cooked[row]          = raw_row;
+                counters_need_update = true;
+            } else {
+                matrix_need_update = true;
+            }
+        }
+        debounce_pointer++;
+    }
+}
+
+bool debounce_active(void) { return true; }