9 files changed, 332 insertions, 93 deletions

diff --git a/docs/feature_debounce_algo.md b/docs/feature_debounce_algo.md
new file mode 100644
index 000000000..2c694cdfb
--- /dev/null
+++ b/docs/feature_debounce_algo.md
@@ -0,0 +1,53 @@
+# Debounce algorithm
+
+QMK supports multiple debounce algorithms through its debounce API.
+
+The underlying debounce algorithm is determined by which matrix.c file you are using.
+
+The logic for which debounce method called is below. It checks various defines that you have set in rules.mk
+
+```
+ifeq ($(strip $(SPLIT_KEYBOARD)), yes)
+    # Do nothing, debouncing is inside matrix.c inside split_common
+else ifeq ($(strip $(DEBOUNCE_ALGO)), manual)
+    # Do nothing. do your debouncing in matrix.c
+else ifeq ($(strip $(DEBOUNCE_ALGO)), sym_g)
+    TMK_COMMON_SRC += $(DEBOUNCE)/debounce_sym_g.c
+else ifeq ($(strip $(DEBOUNCE_ALGO)), eager_pk)
+    TMK_COMMON_SRC += $(DEBOUNCE)/debounce_eager_pk.c
+else ifeq ($(strip $(CUSTOM_MATRIX)), yes)
+    # Do nothing. Custom matrix code.
+else # default algorithm
+    TMK_COMMON_SRC += $(DEBOUNCE)/debounce_sym_g.c
+endif
+```
+
+# Debounce selection
+The following is for keyboards where ```SPLIT_KEYBOARD``` is **not** defined as ```YES```
+
+| DEBOUNCE_ALGO    | CUSTOM_MATRIX | Description                                                 | What to do                    |
+| -------------    |  -------------| ---------------------------------------------------         | ----------------------------- |
+| Not defined      | Not defined   | You are using the included matrix.c and debounce.c          | Nothing. Debounce_sym_g used. |
+| manual           | Not defined   | You are using the included matrix.c but your own debounce.c | ```SRC += debounce.c``` add your own debounce.c and implement necessary functions |
+| sym_g / eager_pk | Not defined   | You are using the included matrix.c and debounce.c          | Nothing. Chosen debounce method used. |
+| Not defined      | YES           | You have your own matrix.c, and your own debounce           | Write the fully debounced matrix into matrix.c's matrix |
+| manual           | YES           | Same as above                                               | same as above                                           |
+| sym_g/ eager_pk  | YES           | You are using your own matrix.c, but included debounce      | Write the raw matrix values into matrix.c's matrix      |
+
+**Note**: 
+If ```SPLIT_KEYBOARD = YES``` is defined, the algorithm inside split_common will be used.
+A future pull request will fix this to use the debounce.c code.
+
+# Use your own debouncing code
+* Set ```DEBOUNCE_ALGO = manual```.
+* Add ```SRC += debounce.c```
+* Add your own ```debounce.c```. Look at included debounce.c's for sample implementations.
+* Debouncing occurs after every raw matrix scan.
+
+# Changing between included debouncing methods
+You can either use your own code, by including your own debounce.c, or switch to another included one.
+Included debounce methods are:
+* debounce_eager_pk - debouncing per key. On any state change, response is immediate, followed by ```DEBOUNCE_DELAY``` millseconds of no further input for that key
+* debounce_sym_g - debouncing per keyboard. On any state change, a global timer is set. When ```DEBOUNCE_DELAY``` milliseconds of no changes has occured, all input changes are pushed.
+
+
diff --git a/quantum/matrix.c b/quantum/matrix.c
index 9b5ce33d2..292171490 100644
--- a/quantum/matrix.c
+++ b/quantum/matrix.c
@@ -25,17 +25,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "quantum.h"
 
 
-/* Set 0 if debouncing isn't needed */
-
-#ifndef DEBOUNCING_DELAY
-#   define DEBOUNCING_DELAY 5
-#endif
-
-#if (DEBOUNCING_DELAY > 0)
-    static uint16_t debouncing_time;
-    static bool debouncing = false;
-#endif
-
 #if (MATRIX_COLS <= 8)
 #    define print_matrix_header()  print("\nr/c 01234567\n")
 #    define print_matrix_row(row)  print_bin_reverse8(matrix_get_row(row))
@@ -65,8 +54,6 @@ static const pin_t col_pins[MATRIX_COLS] = MATRIX_COL_PINS;
 /* matrix state(1:on, 0:off) */
 static matrix_row_t matrix[MATRIX_ROWS];
 
-static matrix_row_t matrix_debouncing[MATRIX_ROWS];
-
 
 #if (DIODE_DIRECTION == COL2ROW)
     static void init_cols(void);
@@ -120,30 +107,6 @@ uint8_t matrix_cols(void) {
     return MATRIX_COLS;
 }
 
-// void matrix_power_up(void) {
-// #if (DIODE_DIRECTION == COL2ROW)
-//     for (int8_t r = MATRIX_ROWS - 1; r >= 0; --r) {
-//         /* DDRxn */
-//         _SFR_IO8((row_pins[r] >> 4) + 1) |= _BV(row_pins[r] & 0xF);
-//         toggle_row(r);
-//     }
-//     for (int8_t c = MATRIX_COLS - 1; c >= 0; --c) {
-//         /* PORTxn */
-//         _SFR_IO8((col_pins[c] >> 4) + 2) |= _BV(col_pins[c] & 0xF);
-//     }
-// #elif (DIODE_DIRECTION == ROW2COL)
-//     for (int8_t c = MATRIX_COLS - 1; c >= 0; --c) {
-//         /* DDRxn */
-//         _SFR_IO8((col_pins[c] >> 4) + 1) |= _BV(col_pins[c] & 0xF);
-//         toggle_col(c);
-//     }
-//     for (int8_t r = MATRIX_ROWS - 1; r >= 0; --r) {
-//         /* PORTxn */
-//         _SFR_IO8((row_pins[r] >> 4) + 2) |= _BV(row_pins[r] & 0xF);
-//     }
-// #endif
-// }
-
 void matrix_init(void) {
 
     // initialize row and col
@@ -158,7 +121,6 @@ void matrix_init(void) {
     // initialize matrix state: all keys off
     for (uint8_t i=0; i < MATRIX_ROWS; i++) {
         matrix[i] = 0;
-        matrix_debouncing[i] = 0;
     }
 
     matrix_init_quantum();
@@ -168,59 +130,24 @@ uint8_t matrix_scan(void)
 {
 
 #if (DIODE_DIRECTION == COL2ROW)
-
     // Set row, read cols
     for (uint8_t current_row = 0; current_row < MATRIX_ROWS; current_row++) {
-#       if (DEBOUNCING_DELAY > 0)
-            bool matrix_changed = read_cols_on_row(matrix_debouncing, current_row);
-
-            if (matrix_changed) {
-                debouncing = true;
-                debouncing_time = timer_read();
-            }
-
-#       else
-            read_cols_on_row(matrix, current_row);
-#       endif
-
+        read_cols_on_row(matrix, current_row);
     }
-
 #elif (DIODE_DIRECTION == ROW2COL)
-
     // Set col, read rows
     for (uint8_t current_col = 0; current_col < MATRIX_COLS; current_col++) {
-#       if (DEBOUNCING_DELAY > 0)
-            bool matrix_changed = read_rows_on_col(matrix_debouncing, current_col);
-            if (matrix_changed) {
-                debouncing = true;
-                debouncing_time = timer_read();
-            }
-#       else
-             read_rows_on_col(matrix, current_col);
-#       endif
-
+        read_rows_on_col(matrix, current_col);
     }
-
 #endif
 
-#   if (DEBOUNCING_DELAY > 0)
-        if (debouncing && (timer_elapsed(debouncing_time) > DEBOUNCING_DELAY)) {
-            for (uint8_t i = 0; i < MATRIX_ROWS; i++) {
-                matrix[i] = matrix_debouncing[i];
-            }
-            debouncing = false;
-        }
-#   endif
-
     matrix_scan_quantum();
     return 1;
 }
 
+//Deprecated.
 bool matrix_is_modified(void)
 {
-#if (DEBOUNCING_DELAY > 0)
-    if (debouncing) return false;
-#endif
     return true;
 }
 
diff --git a/tmk_core/common.mk b/tmk_core/common.mk
index 063115acb..7a7b3928f 100644
--- a/tmk_core/common.mk
+++ b/tmk_core/common.mk
@@ -1,4 +1,5 @@
 COMMON_DIR = common
+DEBOUNCE = $(COMMON_DIR)/debounce
 ifeq ($(PLATFORM),AVR)
         PLATFORM_COMMON_DIR = $(COMMON_DIR)/avr
 else ifeq ($(PLATFORM),CHIBIOS)
@@ -11,6 +12,7 @@ endif
 
 TMK_COMMON_SRC +=       $(COMMON_DIR)/host.c \
         $(COMMON_DIR)/keyboard.c \
+        $(COMMON_DIR)/debounce.c \
         $(COMMON_DIR)/action.c \
         $(COMMON_DIR)/action_tapping.c \
         $(COMMON_DIR)/action_macro.c \
@@ -60,7 +62,20 @@ ifeq ($(PLATFORM),TEST)
         TMK_COMMON_SRC += $(PLATFORM_COMMON_DIR)/eeprom.c
 endif
 
-
+# Debounce Modules. If implemented in matrix.c, don't use these.
+ifeq ($(strip $(SPLIT_KEYBOARD)), yes)
+    # Do nothing, debouncing is inside matrix.c inside split_common
+else ifeq ($(strip $(DEBOUNCE_ALGO)), manual)
+    # Do nothing. do your debouncing in matrix.c
+else ifeq ($(strip $(DEBOUNCE_ALGO)), sym_g)
+    TMK_COMMON_SRC += $(DEBOUNCE)/debounce_sym_g.c
+else ifeq ($(strip $(DEBOUNCE_ALGO)), eager_pk)
+    TMK_COMMON_SRC += $(DEBOUNCE)/debounce_eager_pk.c
+else ifeq ($(strip $(CUSTOM_MATRIX)), yes)
+    # Do nothing. Custom matrix code.
+else # default algorithm
+    TMK_COMMON_SRC += $(DEBOUNCE)/debounce_sym_g.c
+endif
 
 # Option modules
 BOOTMAGIC_ENABLE ?= no
diff --git a/tmk_core/common/debounce.c b/tmk_core/common/debounce.c
new file mode 100644
index 000000000..406d2d0f3
--- /dev/null
+++ b/tmk_core/common/debounce.c
@@ -0,0 +1,22 @@
+/*
+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/>.
+*/
+#include "debounce.h"
+#include "matrix.h"
+//Default implementation - no debouncing
+__attribute__((weak)) void matrix_debounce_init(void) {}
+__attribute__((weak)) void matrix_debounce(void) {}
+__attribute__((weak)) matrix_row_t matrix_debounce_get_row(uint8_t row)
+{
+  return matrix_get_row(row);
+}
diff --git a/tmk_core/common/debounce.h b/tmk_core/common/debounce.h
new file mode 100644
index 000000000..fe3effab3
--- /dev/null
+++ b/tmk_core/common/debounce.h
@@ -0,0 +1,21 @@
+#ifndef DEBOUNCE_H
+#define DEBOUNCE_H
+#include <stdbool.h>
+#include <stdint.h>
+#include "matrix.h"
+#ifdef __cplusplus
+extern "C" {
+#endif
+  /* called to initialize any data stores your implementation has*/
+  void matrix_debounce_init(void);
+  /* call this every keyboard_task to debounce the matrix*/
+  void matrix_debounce(void);
+  /* matrix state on row */
+  matrix_row_t matrix_debounce_get_row(uint8_t row);
+  /* whether a switch is on */
+  bool matrix_debounce_is_on(uint8_t row, uint8_t col);
+
+#ifdef __cplusplus
+}
+#endif
+#endif
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!
diff --git a/tmk_core/common/keyboard.c b/tmk_core/common/keyboard.c
index 6f659b244..1bfd4c9cc 100644
--- a/tmk_core/common/keyboard.c
+++ b/tmk_core/common/keyboard.c
@@ -18,6 +18,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <stdint.h>
 #include "keyboard.h"
 #include "matrix.h"
+#include "debounce.h"
 #include "keymap.h"
 #include "host.h"
 #include "led.h"
@@ -164,6 +165,7 @@ bool is_keyboard_master(void) {
 void keyboard_init(void) {
     timer_init();
     matrix_init();
+    matrix_debounce_init();
 #ifdef QWIIC_ENABLE
     qwiic_init();
 #endif
@@ -216,9 +218,6 @@ void keyboard_init(void) {
 void keyboard_task(void)
 {
     static matrix_row_t matrix_prev[MATRIX_ROWS];
-#ifdef MATRIX_HAS_GHOST
-  //  static matrix_row_t matrix_ghost[MATRIX_ROWS];
-#endif
     static uint8_t led_status = 0;
     matrix_row_t matrix_row = 0;
     matrix_row_t matrix_change = 0;
@@ -227,24 +226,15 @@ void keyboard_task(void)
 #endif
 
     matrix_scan();
+    matrix_debounce();
+
     if (is_keyboard_master()) {
         for (uint8_t r = 0; r < MATRIX_ROWS; r++) {
-            matrix_row = matrix_get_row(r);
+            matrix_row = matrix_debounce_get_row(r);
             matrix_change = matrix_row ^ matrix_prev[r];
             if (matrix_change) {
 #ifdef MATRIX_HAS_GHOST
-                if (has_ghost_in_row(r, matrix_row)) {
-                    /* Keep track of whether ghosted status has changed for
-                    * debugging. But don't update matrix_prev until un-ghosted, or
-                    * the last key would be lost.
-                    */
-                    //if (debug_matrix && matrix_ghost[r] != matrix_row) {
-                    //    matrix_print();
-                    //}
-                    //matrix_ghost[r] = matrix_row;
-                    continue;
-                }
-                //matrix_ghost[r] = matrix_row;
+                if (has_ghost_in_row(r, matrix_row)) continue;
 #endif
                 if (debug_matrix) matrix_print();
                 for (uint8_t c = 0; c < MATRIX_COLS; c++) {