[Keymap] Adding bdk keymap for ergobox_ez (#4850)

* Adding bdk keymap

* Updating keymap after review from drashna

4 files changed, 220 insertions, 0 deletions

diff --git a/keyboards/ergodox_ez/keymaps/bdk/config.h b/keyboards/ergodox_ez/keymaps/bdk/config.h
new file mode 100644
index 000000000..e824b7310
--- /dev/null
+++ b/keyboards/ergodox_ez/keymaps/bdk/config.h
@@ -0,0 +1,5 @@
+#pragma once
+
+#define ONESHOT_TAP_TOGGLE 2
+#define ONESHOT_TIMEOUT 167
+#define FORCE_NKRO
diff --git a/keyboards/ergodox_ez/keymaps/bdk/keymap.c b/keyboards/ergodox_ez/keymaps/bdk/keymap.c
new file mode 100644
index 000000000..20af6c18e
--- /dev/null
+++ b/keyboards/ergodox_ez/keymaps/bdk/keymap.c
@@ -0,0 +1,176 @@
+#include QMK_KEYBOARD_H
+
+#define SHIFT_DOWN() (get_mods() & (MOD_BIT(KC_LSFT)|MOD_BIT(KC_RSFT)))
+#define KC_FKEYS MO(FKEYS)
+
+// Layers
+enum {
+    BASE=0,
+    SYMNUM,  // Symbols and numbers (activated by holding enter)
+    FKEYS,   // Function keys (activated by a thumb button)
+};
+
+// counter that increments on all key press events.  This is needed for our LT
+// handling
+uint16_t press_counter = 0;
+
+const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
+
+// Keymap 0: Base layer
+
+[BASE] = LAYOUT_ergodox(
+  // left hand ---------------------------------------------------------------------------------------------------
+  KC_NO,          KC_EXLM,        KC_AT,          KC_HASH,        KC_DLR,         KC_PERC,        KC_NO,
+  KC_GRV,         KC_QUOT,        KC_COMM,        KC_DOT,         KC_P,           KC_Y,           KC_LGUI,
+  KC_SLSH,        KC_A,           KC_O,           KC_E,           KC_U,           KC_I,
+  KC_LSFT,        KC_SCLN,        KC_Q,           KC_J,           KC_K,           KC_X,           KC_HOME,
+  KC_LCTL,        KC_LALT,        KC_PGUP,        KC_PGDN,        KC_NO,
+  // left thumb --------------------------------------------------------------------------------------------------
+                                                                                  KC_NO,          KC_NO,
+                                                                                                  KC_NO,
+                                                                  KC_SPC,         KC_TAB,         KC_FKEYS,
+  // right hand --------------------------------------------------------------------------------------------------
+  KC_NO,          KC_CIRC,        KC_AMPR,        KC_ASTR,        KC_LPRN,        KC_RPRN,        KC_NO,
+  KC_RGUI,        KC_F,           KC_G,           KC_C,           KC_R,           KC_L,           KC_BSLS,
+                  KC_D,           KC_H,           KC_T,           KC_N,           KC_S,           KC_MINS,
+  KC_END,         KC_B,           KC_M,           KC_W,           KC_V,           KC_Z,           KC_RSFT,
+                  KC_LEFT,        KC_UP,          KC_DOWN,        KC_RIGHT,       KC_RCTL,
+  // right thumb -------------------------------------------------------------------------------------------------
+  KC_NO,          KC_NO,
+  KC_NO,
+  KC_DEL,         KC_BSPC,        KC_ENT
+),
+// SYMNUM -- numpad and function keys
+[SYMNUM] = LAYOUT_ergodox(
+  // left hand ---------------------------------------------------------------------------------------------------
+  KC_TRNS,        LALT(KC_1),     LALT(KC_2),     LALT(KC_3),     LALT(KC_4),     LALT(KC_5),     KC_TRNS,
+  KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_AMPR,        KC_TRNS,        KC_TRNS,
+  KC_TRNS,        KC_LCBR,        KC_LBRC,        KC_LPRN,        KC_0,           KC_MINS,
+  KC_TRNS,        KC_6,           KC_7,           KC_8,           KC_9,           KC_SLSH,        KC_TRNS,
+  KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,
+  // left thumb --------------------------------------------------------------------------------------------------
+                                                                                  KC_TRNS,        KC_TRNS,
+                                                                                                  KC_TRNS,
+                                                                  KC_TRNS,        KC_TRNS,        KC_TRNS,
+  // right hand --------------------------------------------------------------------------------------------------
+  KC_TRNS,        LALT(KC_6),     LALT(KC_7),     LALT(KC_8),     LALT(KC_9),     LALT(KC_0),     KC_TRNS,
+  KC_TRNS,        KC_PERC,        KC_EQL,         KC_LT,          KC_GT,          KC_EXLM,        KC_TRNS,
+                  KC_PLUS,        KC_1,           KC_RPRN,        KC_RBRC,        KC_RCBR,        KC_TRNS,
+  KC_TRNS,        KC_ASTR,        KC_2,           KC_3,           KC_4,           KC_5,           KC_TRNS,
+                  KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,
+  // right thumb -------------------------------------------------------------------------------------------------
+  KC_TRNS,        KC_TRNS,
+  KC_TRNS,
+  KC_TRNS,        KC_TRNS,        KC_TRNS
+),
+// FKEYS -- function keys
+[FKEYS] = LAYOUT_ergodox(
+  // left hand ---------------------------------------------------------------------------------------------------
+  KC_TRNS,        KC_F1,          KC_F2,          KC_F3,          KC_F4,          KC_F5,          KC_F6,
+  KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,
+  KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,
+  KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,
+  KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,
+  // left thumb --------------------------------------------------------------------------------------------------
+                                                                                  KC_TRNS,        KC_TRNS,
+                                                                                                  KC_TRNS,
+                                                                  KC_TRNS,        KC_TRNS,        KC_TRNS,
+  // right hand --------------------------------------------------------------------------------------------------
+  KC_F7,          KC_F8,          KC_F9,          KC_F10,         KC_F11,         KC_F12,         KC_TRNS,
+  KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,
+                  KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,
+  KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,
+                  KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,        KC_TRNS,
+  // right thumb -------------------------------------------------------------------------------------------------
+  KC_TRNS,        KC_TRNS,
+  KC_TRNS,
+  KC_TRNS,        KC_TRNS,        KC_TRNS
+),
+};
+
+// Code to handle layer tap.
+//
+// The default code doesn't work for me, so I rolled my own code.  The main
+// difference is that it always tries to send modifier+key combination, rather
+// than two keys.  One place where this is noticable is if you tap the key,
+// then try hold it.
+
+struct tap_start_info {
+    uint16_t timer;
+    uint16_t initial_press_counter;
+};
+
+static struct tap_start_info tap_start_infos[5];
+
+// Quick check to see if a key is down.  Note that this requires NKRO enabled
+static bool key_down(uint8_t code) {
+    return (keyboard_report->nkro.bits[code>>3] & 1<<(code&7)) != 0;
+}
+
+static bool handle_lt(uint16_t keycode, keyrecord_t *record, uint8_t layer, uint8_t index) {
+    struct tap_start_info* tap_start = tap_start_infos + index;
+
+    if(record->event.pressed) {
+        layer_on(layer);
+        tap_start->timer = timer_read();
+        tap_start->initial_press_counter = press_counter;
+    } else {
+        layer_off(layer);
+        // Only click the key if:
+        //   - No other keys are pressed between the press and release events
+        //   - The release happens before the ONESHOT_TIMEOUT
+        if(press_counter == tap_start->initial_press_counter && timer_elapsed(tap_start->timer) < ONESHOT_TIMEOUT) {
+            register_code16(keycode);
+            unregister_code16(keycode);
+        }
+    }
+    return false;
+}
+
+static bool handle_mt(uint16_t keycode, keyrecord_t *record, uint8_t mods, uint8_t index) {
+    struct tap_start_info* tap_start = tap_start_infos + index;
+
+    if(record->event.pressed) {
+        register_mods(mods);
+        tap_start->timer = timer_read();
+        tap_start->initial_press_counter = press_counter;
+    } else {
+        unregister_mods(mods);
+        // Only click the key if:
+        //   - No other keys are pressed between the press and release events
+        //   - The release happens before the ONESHOT_TIMEOUT
+        if(press_counter == tap_start->initial_press_counter && timer_elapsed(tap_start->timer) < ONESHOT_TIMEOUT) {
+            register_code16(keycode);
+            unregister_code16(keycode);
+        }
+    }
+    return false;
+}
+
+bool process_record_user(uint16_t keycode, keyrecord_t *record) {
+    if(record->event.pressed) {
+        press_counter++;
+        // The symbol layer allows sequences repeat the same "physical" key.
+        // For example "0)", which is like pressing the "0" key twice in a
+        // row.  It's very easy to make a sequence of these where the ")"
+        // press comes before the "0" release.  If that happens, force a
+        // release of the "0" key, otherwise nothing will happen.
+        uint8_t shortcode = keycode & 0xFF;
+        if(key_down(shortcode)) {
+            unregister_code(shortcode);
+        }
+    }
+
+    switch(keycode) {
+        case KC_ENTER:
+            return handle_lt(keycode, record, SYMNUM, 0);
+
+        case KC_TAB:
+            return handle_mt(keycode, record, MOD_BIT(KC_LCTL), 1);
+
+        case KC_LSFT:
+        case KC_RSFT:
+            return handle_mt(KC_ESC, record, MOD_BIT(keycode), 2);
+    }
+    return true;
+}
diff --git a/keyboards/ergodox_ez/keymaps/bdk/readme.md b/keyboards/ergodox_ez/keymaps/bdk/readme.md
new file mode 100644
index 000000000..36a211d32
--- /dev/null
+++ b/keyboards/ergodox_ez/keymaps/bdk/readme.md
@@ -0,0 +1,36 @@
+# The BDK Ergodox Keyboard Layout
+
+## Dvorak-based
+
+This was the first alternative layout I switched to and I don't want to change
+again.
+
+## Mod-tap / Layer-tap is great for thumb keys
+
+This means a key that activates a layer/modifier when you hold it down, but
+results in a keyclick when you tap it.  Thumb keys are great for this since
+they are good for both high-usage keys as well as modifiers.
+
+The one thing to avoid is when you mean to tap a key, but hit the next key
+before you release, which results in the modifier/layer instead of a tap.  To
+avoid this, I chose Enter/Tab as the tap keys, since they aren't chorded
+together with other keys often.
+
+The other issue is I found several problems with using the standard MT,LT code,
+so I rolled my own to handle it.
+
+## Don't have too many layers
+
+My first layouts had multiple layers that I could switch to, but that
+overloaded my brain.  This layout basically only uses 1 extra layer.
+Technically there's also a function key layer, but I only use those keys for
+a handlful of things: boot order, rename, reload page, that's basically it.
+
+## Brackets should be easy to use
+
+There's a lot of ways to lay out a symbol layer.  I organized mine around
+making the {[()]} chars easy to use since they're so frequent in programming.
+I put them all on the symbol layer home row.
+
+I also arranged the numbers so 0/1 were also on the symbol layer home row.
+This makes for fairly easy chording of "[0]" and "[1]".
diff --git a/keyboards/ergodox_ez/keymaps/bdk/rules.mk b/keyboards/ergodox_ez/keymaps/bdk/rules.mk
new file mode 100644
index 000000000..6c5163623
--- /dev/null
+++ b/keyboards/ergodox_ez/keymaps/bdk/rules.mk
@@ -0,0 +1,3 @@
+# CONSOLE_ENABLE   = yes
+# DEBUG_ENABLE = yes
+COMMAND_ENABLE   = no