Optimize matrix scanning (#343)

1 files changed, 56 insertions, 78 deletions

diff --git a/tmk_core/common/keyboard.c b/tmk_core/common/keyboard.c
index 1d99818481..c6d54ae333 100644
--- a/tmk_core/common/keyboard.c
+++ b/tmk_core/common/keyboard.c
@@ -1,5 +1,5 @@
 /*
-Copyright 2011,2012,2013 Jun Wako <wakojun@gmail.com>
+Copyright 2011, 2012, 2013 Jun Wako <wakojun@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
@@ -27,13 +27,13 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "command.h"
 #include "util.h"
 #include "sendchar.h"
+#include "eeconfig.h"
+#include "backlight.h"
 #ifdef BOOTMAGIC_ENABLE
-    #include "bootmagic.h"
+#   include "bootmagic.h"
 #else
-    #include "magic.h"
+#   include "magic.h"
 #endif
-#include "eeconfig.h"
-#include "backlight.h"
 #ifdef MOUSEKEY_ENABLE
 #   include "mousekey.h"
 #endif
@@ -41,40 +41,35 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #   include "ps2_mouse.h"
 #endif
 #ifdef SERIAL_MOUSE_ENABLE
-#include "serial_mouse.h"
+#   include "serial_mouse.h"
 #endif
 #ifdef ADB_MOUSE_ENABLE
-#include "adb.h"
+#   include "adb.h"
 #endif
 
-
 #ifdef MATRIX_HAS_GHOST
-static bool has_ghost_in_row(uint8_t row)
-{
-    matrix_row_t matrix_row = matrix_get_row(row);
-    // No ghost exists when less than 2 keys are down on the row
-    if (((matrix_row - 1) & matrix_row) == 0)
-        return false;
-
-    // Ghost occurs when the row shares column line with other row
-    for (uint8_t i=0; i < MATRIX_ROWS; i++) {
-        if (i != row && (matrix_get_row(i) & matrix_row))
-            return true;
+static bool is_row_ghosting(uint8_t row){
+    matrix_row_t state = matrix_get_row(row);
+    /* no ghosting happens when only one key in the row is pressed */
+    if (!(state - 1 & state)) return false;
+    /* ghosting occurs when two keys in the same column are pressed */
+    for (int8_t r = MATRIX_ROWS - 1; r >= 0; --r) {
+        if (r != row && matrix_get_row(r) & state) return true;
     }
     return false;
 }
+
 #endif
 
+__attribute__ ((weak))
+void matrix_setup(void) {
+}
 
-__attribute__ ((weak)) void matrix_setup(void) {}
-void keyboard_setup(void)
-{
+void keyboard_setup(void) {
     matrix_setup();
 }
 
-void keyboard_init(void)
-{
-
+void keyboard_init(void) {
     timer_init();
     matrix_init();
 #ifdef PS2_MOUSE_ENABLE
@@ -86,104 +81,87 @@ void keyboard_init(void)
 #ifdef ADB_MOUSE_ENABLE
     adb_mouse_init();
 #endif
-
-
 #ifdef BOOTMAGIC_ENABLE
     bootmagic();
 #else
     magic();
 #endif
-
 #ifdef BACKLIGHT_ENABLE
     backlight_init();
 #endif
-
 #if defined(NKRO_ENABLE) && defined(FORCE_NKRO)
 	keyboard_nkro = true;
 #endif
-
 }
 
-/*
- * Do keyboard routine jobs: scan mantrix, light LEDs, ...
- * This is repeatedly called as fast as possible.
- */
-void keyboard_task(void)
-{
-    static matrix_row_t matrix_prev[MATRIX_ROWS];
+/* does routine keyboard jobs */
+void keyboard_task(void) {
+    static matrix_row_t previous_matrix[MATRIX_ROWS];
 #ifdef MATRIX_HAS_GHOST
-    static matrix_row_t matrix_ghost[MATRIX_ROWS];
+    static matrix_row_t deghosting_matrix[MATRIX_ROWS];
 #endif
     static uint8_t led_status = 0;
-    matrix_row_t matrix_row = 0;
-    matrix_row_t matrix_change = 0;
-
     matrix_scan();
-    for (uint8_t r = 0; r < MATRIX_ROWS; r++) {
-        matrix_row = matrix_get_row(r);
-        matrix_change = matrix_row ^ matrix_prev[r];
-        if (matrix_change) {
+    for (int8_t r = MATRIX_ROWS - 1; r >= 0; --r) {
+        matrix_row_t state = matrix_get_row(r);
+        matrix_row_t changes = state ^ previous_matrix[r];
+        if (changes) {
 #ifdef MATRIX_HAS_GHOST
-            if (has_ghost_in_row(r)) {
-                /* 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 (is_row_ghosting(r)) {
+                /* debugs the deghosting mechanism */
+                /* doesn't update previous_matrix until the ghosting has stopped
+                 * in order to prevent the last key from being lost
                  */
-                if (debug_matrix && matrix_ghost[r] != matrix_row) {
+                if (debug_matrix && deghosting_matrix[r] != state) {
                     matrix_print();
                 }
-                matrix_ghost[r] = matrix_row;
+                deghosting_matrix[r] = state;
                 continue;
             }
-            matrix_ghost[r] = matrix_row;
+            deghosting_matrix[r] = state;
 #endif
             if (debug_matrix) matrix_print();
-            for (uint8_t c = 0; c < MATRIX_COLS; c++) {
-                if (matrix_change & ((matrix_row_t)1<<c)) {
-                    action_exec((keyevent_t){
-                        .key = (keypos_t){ .row = r, .col = c },
-                        .pressed = (matrix_row & ((matrix_row_t)1<<c)),
-                        .time = (timer_read() | 1) /* time should not be 0 */
-                    });
-                    // record a processed key
-                    matrix_prev[r] ^= ((matrix_row_t)1<<c);
-                    // process a key per task call
-                    goto MATRIX_LOOP_END;
+            for (int8_t c = MATRIX_COLS - 1; c >= 0; --c) {
+                matrix_row_t mask = (matrix_row_t)1 << c;
+                if (changes & mask) {
+                    keyevent_t event;
+                    event.key = (keypos_t){ .row = r, .col = c };
+                    event.pressed = state & mask;
+                    /* the time should not be 0 */
+                    event.time = timer_read() | 1;
+                    action_exec(event);
+                    /* records the processed key event */
+                    previous_matrix[r] ^= mask;
+                    /* processes one key event per call */
+                    goto event_processed;
                 }
             }
         }
     }
-    // call with pseudo tick event when no real key event.
+    /* sends tick events when the keyboard is idle */
     action_exec(TICK);
-
-MATRIX_LOOP_END:
-
+event_processed:
 #ifdef MOUSEKEY_ENABLE
-    // mousekey repeat & acceleration
+    /* repeats and accelerates the mouse keys */
     mousekey_task();
 #endif
-
 #ifdef PS2_MOUSE_ENABLE
     ps2_mouse_task();
 #endif
-
 #ifdef SERIAL_MOUSE_ENABLE
-        serial_mouse_task();
+    serial_mouse_task();
 #endif
-
 #ifdef ADB_MOUSE_ENABLE
-        adb_mouse_task();
+    adb_mouse_task();
 #endif
-
-    // update LED
+    /* updates the LEDs */
     if (led_status != host_keyboard_leds()) {
         led_status = host_keyboard_leds();
         keyboard_set_leds(led_status);
     }
 }
 
-void keyboard_set_leds(uint8_t leds)
-{
-    if (debug_keyboard) { debug("keyboard_set_led: "); debug_hex8(leds); debug("\n"); }
+void keyboard_set_leds(uint8_t leds) {
+    if (debug_keyboard) dprintf("Keyboard LEDs state: %x\n", leds);
     led_set(leds);
 }