Eager Per Row Debouncing added (added to Ergodox) (#5498)

* Implemented Eager Per Row debouncing algorithm.

Good for when fingers can only press one row at a time (e.g. when keyboard is wired so that "rows" are vertical)

* Added documentation for eager_pr

* Ported ergodox_ez to eager_pr debouncing.

* Removed check for changes in matrix_scan.

* Added further clarification in docs.

* Accidental merge with ergodox_ez

* Small cleanup in eager_pr

* Forgot to debounce_init - this would probably cause seg-faults.

2 files changed, 101 insertions, 1 deletions

diff --git a/quantum/debounce/eager_pr.c b/quantum/debounce/eager_pr.c
new file mode 100644
index 0000000000..9eb9480a79
--- /dev/null
+++ b/quantum/debounce/eager_pr.c
@@ -0,0 +1,100 @@
+/*
+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 debounce_counter_t *debounce_counters;
+
+#define DEBOUNCE_ELAPSED 251
+#define MAX_DEBOUNCE (DEBOUNCE_ELAPSED - 1)
+
+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 = timer_read() % MAX_DEBOUNCE;
+  update_debounce_counters(num_rows, current_time);
+  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)
+{
+  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;
+      }
+    }
+    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)
+{
+  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 (*debounce_pointer == DEBOUNCE_ELAPSED &&
+      (existing_row != raw_row))
+    {
+      *debounce_pointer = current_time;
+      existing_row = raw_row; 
+    }
+    cooked[row] = existing_row;
+    
+    debounce_pointer++;
+  }  
+}
+
+bool debounce_active(void)
+{
+  return true;
+}
+
diff --git a/quantum/debounce/readme.md b/quantum/debounce/readme.md
index 5b318d845e..f77f78c764 100644
--- a/quantum/debounce/readme.md
+++ b/quantum/debounce/readme.md
@@ -22,7 +22,7 @@ Here are a few that could be implemented:
 sym_g.c
 sym_pk.c
 sym_pr.c
-sym_pr_cycles.c //currently used in ergo-dox
+sym_pr_cycles.c 
 eager_g.c
 eager_pk.c
 eager_pr.c //could be used in ergo-dox!