3 files changed, 211 insertions, 0 deletions

diff --git a/tmk_core/common/debounce/debounce_eager_pk.c b/tmk_core/common/debounce/debounce_eager_pk.c
new file mode 100644
index 000000000..984da0570
--- /dev/null
+++ b/tmk_core/common/debounce/debounce_eager_pk.c
@@ -0,0 +1,124 @@
+/*
+Copyright 2017 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-key algorithm. Uses an 8-bit counter per key.
+After pressing a key, it immediately changes state, and sets a counter.
+No further inputs are accepted until DEBOUNCE milliseconds have occurred.
+*/
+
+#include "debounce.h"
+#include "matrix.h"
+#include "timer.h"
+
+#ifndef DEBOUNCE
+  #define DEBOUNCE 5
+#endif
+
+
+#if (MATRIX_COLS <= 8)
+#    define ROW_SHIFTER ((uint8_t)1)
+#elif (MATRIX_COLS <= 16)
+#    define ROW_SHIFTER ((uint16_t)1)
+#elif (MATRIX_COLS <= 32)
+#    define ROW_SHIFTER  ((uint32_t)1)
+#endif
+
+
+
+#define debounce_counter_t uint8_t
+
+static matrix_row_t matrix_debounced[MATRIX_ROWS];
+static debounce_counter_t debounce_counters[MATRIX_ROWS*MATRIX_COLS];
+
+#define DEBOUNCE_ELAPSED 251
+#define MAX_DEBOUNCE (DEBOUNCE_ELAPSED - 1)
+
+void update_debounce_counters(uint8_t current_time);
+void transfer_matrix_values(uint8_t current_time);
+
+void matrix_debounce_init(void)
+{
+  for (uint8_t r = 0; r < MATRIX_ROWS; r++)
+  {
+    matrix_debounced[r] = 0;
+  }
+
+  int i = 0;
+  for (uint8_t r = 0; r < MATRIX_ROWS; r++)
+  {
+    for (uint8_t c = 0; c < MATRIX_COLS; c++)
+    {
+      debounce_counters[i++] = DEBOUNCE_ELAPSED;
+    }
+  }
+}
+
+void matrix_debounce(void)
+{
+  uint8_t current_time = timer_read() % MAX_DEBOUNCE;
+  update_debounce_counters(current_time);
+  transfer_matrix_values(current_time);
+}
+
+//If the current time is > debounce counter, set the counter to enable input.
+void update_debounce_counters(uint8_t current_time)
+{
+  debounce_counter_t *debounce_pointer = debounce_counters;
+  for (uint8_t row = 0; row < MATRIX_ROWS; row++)
+  {
+    for (uint8_t col = 0; col < MATRIX_COLS; col++)
+    {
+      if (*debounce_pointer != DEBOUNCE_ELAPSED)
+      {
+        if (TIMER_DIFF(current_time, *debounce_pointer, MAX_DEBOUNCE) >=
+            DEBOUNCING_DELAY) {
+          *debounce_pointer = DEBOUNCE_ELAPSED;
+        }
+      }
+      debounce_pointer++;
+    }
+  }
+}
+
+// upload from raw_matrix to final matrix;
+void transfer_matrix_values(uint8_t current_time)
+{
+  debounce_counter_t *debounce_pointer = debounce_counters;
+  for (uint8_t row = 0; row < MATRIX_ROWS; row++)
+  {
+    matrix_row_t existing_row = matrix_debounced[row]; 
+    matrix_row_t raw_row = matrix_get_row(row);
+
+    for (uint8_t col = 0; col < MATRIX_COLS; col++)
+    {
+      matrix_row_t col_mask = (ROW_SHIFTER << col);
+      bool final_value = raw_row & col_mask;
+      bool existing_value = existing_row & col_mask;
+      if (*debounce_pointer == DEBOUNCE_ELAPSED &&
+          (existing_value != final_value))
+      {
+        *debounce_pointer = current_time;
+        existing_row ^= col_mask; //flip the bit.
+      }
+      debounce_pointer++;
+    }
+    matrix_debounced[row] = existing_row;
+  }  
+}
+
+matrix_row_t matrix_debounce_get_row(uint8_t row)
+{
+  return matrix_debounced[row];
+}
diff --git a/tmk_core/common/debounce/debounce_sym_g.c b/tmk_core/common/debounce/debounce_sym_g.c
new file mode 100644
index 000000000..2fb7a589d
--- /dev/null
+++ b/tmk_core/common/debounce/debounce_sym_g.c
@@ -0,0 +1,59 @@
+/*
+Copyright 2017 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 global debounce algorithm. Used in 99% of keyboards at time of implementation
+When no state changes have occured for DEBOUNCE milliseconds, we push the state.
+*/
+#include "debounce.h"
+#include "matrix.h"
+#include "timer.h"
+#ifndef DEBOUNCE
+  #define DEBOUNCE 5
+#endif
+static matrix_row_t matrix_debounced[MATRIX_ROWS];
+static bool debouncing = false;
+static uint16_t debouncing_time;
+
+void matrix_debounce_init(void)
+{
+  for (uint8_t r = 0; r < MATRIX_ROWS; r++)
+  {
+    matrix_debounced[r] = 0;
+  }
+}
+
+void matrix_debounce(void)
+{
+  for (uint8_t r = 0; r < MATRIX_ROWS; r++)
+  {
+    matrix_row_t raw = matrix_get_row(r);
+    if (raw != matrix_debounced[r])
+    {
+      debouncing = true;
+      debouncing_time = timer_read();
+    }
+  }
+  if (debouncing && timer_elapsed(debouncing_time) > DEBOUNCE) {
+    for (int i = 0; i < MATRIX_ROWS; i++) {
+      matrix_debounced[i] = matrix_get_row(i);
+    }
+    debouncing = false;
+  }
+}
+
+matrix_row_t matrix_debounce_get_row(uint8_t row)
+{
+  return matrix_debounced[row];
+}
diff --git a/tmk_core/common/debounce/readme.md b/tmk_core/common/debounce/readme.md
new file mode 100644
index 000000000..1a77d44df
--- /dev/null
+++ b/tmk_core/common/debounce/readme.md
@@ -0,0 +1,28 @@
+Debounce algorithms belong in this folder.
+Here are a few ideas
+
+1) Global vs Per-Key vs Per-Row
+ * Global - one timer for all keys. Any key change state affects global timer
+ * Per key - one timer per key
+ * Per row - one timer per row
+
+2) Eager vs symmetric vs assymetric
+ * Eager - any key change is reported immediately. All further inputs for DEBOUNCE ms are ignored.
+ * Symmetric - wait for no changes for DEBOUNCE ms before reporting change
+ * Assymetric - wait for different times depending on key-down/key-up. E.g. Eager key-down, DEBOUNCE ms key up.
+
+3) Timestamp vs cycles
+ * old old old code waits n cycles, decreasing count by one each matrix_scan
+ * newer code stores the millisecond the change occurred, and does subraction to figure out time elapsed.
+ * Timestamps are superior, i don't think cycles will ever be used again once upgraded.
+
+The default algorithm is symmetric and global.
+Here are a few that could be implemented:
+
+debounce_sym_g.c
+debounce_sym_pk.c 
+debounce_sym_pr.c 
+debounce_sym_pr_cycles.c //currently used in ergo-dox
+debounce_eager_g.c
+debounce_eager_pk.c
+debounce_eager_pr.c //could be used in ergo-dox!