1 files changed, 43 insertions, 15 deletions

diff --git a/tmk_core/common/keyboard.c b/tmk_core/common/keyboard.c
index eac1f1dd8..97a8f1cd8 100644
--- a/tmk_core/common/keyboard.c
+++ b/tmk_core/common/keyboard.c
@@ -61,23 +61,51 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #   include "visualizer/visualizer.h"
 #endif
 
+#ifdef MATRIX_HAS_GHOST
+extern const uint16_t keymaps[][MATRIX_ROWS][MATRIX_COLS];
+static matrix_row_t get_real_keys(uint8_t row, matrix_row_t rowdata){
+    matrix_row_t out = 0;
+    for (uint8_t col = 0; col < MATRIX_COLS; col++) {
+        //read each key in the row data and check if the keymap defines it as a real key
+        if (pgm_read_byte(&keymaps[0][row][col]) && (rowdata & (1<<col))){
+            //this creates new row data, if a key is defined in the keymap, it will be set here
+            out |= 1<<col;
+        }
+    }
+    return out;
+}
 
+static inline bool popcount_more_than_one(matrix_row_t rowdata)
+{
+    rowdata &= rowdata-1; //if there are less than two bits (keys) set, rowdata will become zero
+    return rowdata;
+}
 
-#ifdef MATRIX_HAS_GHOST
-static bool has_ghost_in_row(uint8_t row)
+static inline bool has_ghost_in_row(uint8_t row, matrix_row_t rowdata)
 {
-    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)
+    /* No ghost exists when less than 2 keys are down on the row.
+    If there are "active" blanks in the matrix, the key can't be pressed by the user,
+    there is no doubt as to which keys are really being pressed.
+    The ghosts will be ignored, they are KC_NO.   */
+    rowdata = get_real_keys(row, rowdata);
+    if ((popcount_more_than_one(rowdata)) == 0){
         return false;
-
-    // Ghost occurs when the row shares column line with other row
+    }
+    /* Ghost occurs when the row shares a column line with other row,
+    and two columns are read on each row. Blanks in the matrix don't matter,
+    so they are filtered out.
+    If there are two or more real keys pressed and they match columns with
+    at least two of another row's real keys, the row will be ignored. Keep in mind,
+    we are checking one row at a time, not all of them at once.
+    */
     for (uint8_t i=0; i < MATRIX_ROWS; i++) {
-        if (i != row && (matrix_get_row(i) & matrix_row))
+        if (i != row && popcount_more_than_one(get_real_keys(i, matrix_get_row(i)) & rowdata)){
             return true;
+        }
     }
     return false;
 }
+
 #endif
 
 __attribute__ ((weak))
@@ -127,7 +155,7 @@ void keyboard_task(void)
 {
     static matrix_row_t matrix_prev[MATRIX_ROWS];
 #ifdef MATRIX_HAS_GHOST
-    static matrix_row_t matrix_ghost[MATRIX_ROWS];
+  //  static matrix_row_t matrix_ghost[MATRIX_ROWS];
 #endif
     static uint8_t led_status = 0;
     matrix_row_t matrix_row = 0;
@@ -139,18 +167,18 @@ void keyboard_task(void)
         matrix_change = matrix_row ^ matrix_prev[r];
         if (matrix_change) {
 #ifdef MATRIX_HAS_GHOST
-            if (has_ghost_in_row(r)) {
+            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;
+                //if (debug_matrix && matrix_ghost[r] != matrix_row) {
+                //    matrix_print();
+                //}
+                //matrix_ghost[r] = matrix_row;
                 continue;
             }
-            matrix_ghost[r] = matrix_row;
+            //matrix_ghost[r] = matrix_row;
 #endif
             if (debug_matrix) matrix_print();
             for (uint8_t c = 0; c < MATRIX_COLS; c++) {