feat(sticky keys): initial implementation

app/CMakeLists.txt

@@ -41,6 +41,7 @@ if (NOT CONFIG_ZMK_SPLIT_BLE_ROLE_PERIPHERAL)
   target_sources(app PRIVATE src/behaviors/behavior_key_press.c)
   target_sources(app PRIVATE src/behaviors/behavior_reset.c)
   target_sources(app PRIVATE src/behaviors/behavior_hold_tap.c)
+  target_sources(app PRIVATE src/behaviors/behavior_sticky_key.c)
   target_sources(app PRIVATE src/behaviors/behavior_momentary_layer.c)
   target_sources(app PRIVATE src/behaviors/behavior_outputs.c)
   target_sources(app PRIVATE src/behaviors/behavior_toggle_layer.c)

app/dts/behaviors.dtsi

@@ -3,6 +3,7 @@
 #include <behaviors/none.dtsi>
 #include <behaviors/mod_tap.dtsi>
 #include <behaviors/layer_tap.dtsi>
+#include <behaviors/sticky_key.dtsi>
 #include <behaviors/momentary_layer.dtsi>
 #include <behaviors/toggle_layer.dtsi>
 #include <behaviors/reset.dtsi>

app/dts/behaviors/sticky_key.dtsi

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+/ {
+	behaviors {
+		sk: behavior_sticky_key {
+			compatible = "zmk,behavior-sticky-key";
+			label = "STICKY_KEY";
+			#binding-cells = <1>;
+			release-after-ms = <1000>;
+			bindings = <&kp>;
+		};
+		sl: behavior_sticky_layer {
+			compatible = "zmk,behavior-sticky-key";
+			label = "STICKY_LAYER";
+			#binding-cells = <1>;
+			release-after-ms = <1000>;
+			bindings = <&mo>;
+		};
+	};
+
+};
+

app/dts/bindings/behaviors/zmk,behavior-sticky-key.yaml

@@ -0,0 +1,15 @@
+# Copyright (c) 2020 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+description: Sticky key behavior
+
+compatible: "zmk,behavior-sticky-key"
+
+include: one_param.yaml
+
+properties:
+  bindings:
+    type: phandles
+    required: true
+  release-after-ms:
+    type: int 

app/src/behaviors/behavior_sticky_key.c

@@ -0,0 +1,272 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#define DT_DRV_COMPAT zmk_behavior_sticky_key
+
+#include <device.h>
+#include <drivers/behavior.h>
+#include <logging/log.h>
+#include <zmk/behavior.h>
+
+#include <zmk/matrix.h>
+#include <zmk/endpoints.h>
+#include <zmk/event-manager.h>
+#include <zmk/events/position-state-changed.h>
+#include <zmk/events/keycode-state-changed.h>
+#include <zmk/events/modifiers-state-changed.h>
+#include <zmk/hid.h>
+
+LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
+
+#if DT_NODE_EXISTS(DT_DRV_INST(0))
+
+#define ZMK_BHV_STICKY_KEY_MAX_HELD 10
+
+// increase this if you need more keys in the board
+#define ZMK_BHV_STICKY_KEY_POSITION_NOT_USED ULONG_MAX
+
+struct behavior_sticky_key_config {
+    u32_t release_after_ms;
+    struct zmk_behavior_binding behavior;
+};
+
+struct active_sticky_key {
+    u32_t position;
+    u32_t param1;
+    u32_t param2;
+    const struct behavior_sticky_key_config *config;
+    // timer data.
+    bool timer_started;
+    s64_t release_at;
+    struct k_delayed_work release_timer;
+    bool timer_is_cancelled;
+    // usage page and keycode for the key that is being modified by this sticky key
+    u8_t modified_key_usage_page;
+    u32_t modified_key_keycode;
+};
+
+struct active_sticky_key active_sticky_keys[ZMK_BHV_STICKY_KEY_MAX_HELD] = {};
+
+static struct active_sticky_key *store_sticky_key(u32_t position, u32_t param1, u32_t param2,
+                                                  const struct behavior_sticky_key_config *config) {
+    for (int i = 0; i < ZMK_BHV_STICKY_KEY_MAX_HELD; i++) {
+        if (active_sticky_keys[i].position != ZMK_BHV_STICKY_KEY_POSITION_NOT_USED) {
+            continue;
+        }
+        active_sticky_keys[i].position = position;
+        active_sticky_keys[i].param1 = param1;
+        active_sticky_keys[i].param2 = param2;
+        active_sticky_keys[i].config = config;
+        active_sticky_keys[i].release_at = 0;
+        active_sticky_keys[i].timer_is_cancelled = false;
+        active_sticky_keys[i].timer_started = false;
+        active_sticky_keys[i].modified_key_usage_page = 0;
+        active_sticky_keys[i].modified_key_keycode = 0;
+        return &active_sticky_keys[i];
+    }
+    return NULL;
+}
+
+static void clear_sticky_key(struct active_sticky_key *sticky_key) {
+    sticky_key->position = ZMK_BHV_STICKY_KEY_POSITION_NOT_USED;
+}
+
+static struct active_sticky_key *find_sticky_key(u32_t position) {
+    for (int i = 0; i < ZMK_BHV_STICKY_KEY_MAX_HELD; i++) {
+        if (active_sticky_keys[i].position == position) {
+            return &active_sticky_keys[i];
+        }
+    }
+    return NULL;
+}
+
+static inline int press_sticky_key_behavior(struct active_sticky_key *sticky_key, s64_t timestamp) {
+    struct zmk_behavior_binding binding = {
+        .behavior_dev = sticky_key->config->behavior.behavior_dev,
+        .param1 = sticky_key->param1,
+        .param2 = sticky_key->param2,
+    };
+    struct zmk_behavior_binding_event event = {
+        .position = sticky_key->position,
+        .timestamp = timestamp,
+    };
+    return behavior_keymap_binding_pressed(&binding, event);
+}
+
+static inline int release_sticky_key_behavior(struct active_sticky_key *sticky_key,
+                                              s64_t timestamp) {
+    struct zmk_behavior_binding binding = {
+        .behavior_dev = sticky_key->config->behavior.behavior_dev,
+        .param1 = sticky_key->param1,
+        .param2 = sticky_key->param2,
+    };
+    struct zmk_behavior_binding_event event = {
+        .position = sticky_key->position,
+        .timestamp = timestamp,
+    };
+    return behavior_keymap_binding_released(&binding, event);
+}
+
+static int stop_timer(struct active_sticky_key *sticky_key) {
+    int timer_cancel_result = k_delayed_work_cancel(&sticky_key->release_timer);
+    if (timer_cancel_result == -EINPROGRESS) {
+        // too late to cancel, we'll let the timer handler clear up.
+        sticky_key->timer_is_cancelled = true;
+    }
+    return timer_cancel_result;
+}
+
+static int on_sticky_key_binding_pressed(struct zmk_behavior_binding *binding,
+                                         struct zmk_behavior_binding_event event) {
+    struct device *dev = device_get_binding(binding->behavior_dev);
+    const struct behavior_sticky_key_config *cfg = dev->config_info;
+
+    struct active_sticky_key *sticky_key =
+        store_sticky_key(event.position, binding->param1, binding->param2, cfg);
+    if (sticky_key == NULL) {
+        LOG_ERR("unable to store sticky key, did you press more than %d sticky_key?",
+                ZMK_BHV_STICKY_KEY_MAX_HELD);
+        return 0;
+    }
+
+    press_sticky_key_behavior(sticky_key, event.timestamp);
+    LOG_DBG("%d new sticky_key", event.position);
+    return 0;
+}
+
+static int on_sticky_key_binding_released(struct zmk_behavior_binding *binding,
+                                          struct zmk_behavior_binding_event event) {
+    struct active_sticky_key *sticky_key = find_sticky_key(event.position);
+    if (sticky_key == NULL) {
+        LOG_ERR("ACTIVE STICKY KEY CLEARED TOO EARLY");
+        return 0;
+    }
+
+    if (sticky_key->modified_key_usage_page != 0 && sticky_key->modified_key_keycode != 0) {
+        LOG_DBG("Another key was pressed while the sticky key was pressed. Act like a normal key.");
+        int retval = release_sticky_key_behavior(sticky_key, event.timestamp);
+        clear_sticky_key(sticky_key);
+        return retval;
+    }
+
+    // No other key was pressed. Start the timer.
+    sticky_key->timer_started = true;
+    sticky_key->release_at = event.timestamp + sticky_key->config->release_after_ms;
+    // adjust timer in case this behavior was queued by a hold-tap
+    s32_t ms_left = sticky_key->release_at - k_uptime_get();
+    if (ms_left > 0) {
+        k_delayed_work_submit(&sticky_key->release_timer, K_MSEC(ms_left));
+    }
+    return 0;
+}
+
+static const struct behavior_driver_api behavior_sticky_key_driver_api = {
+    .binding_pressed = on_sticky_key_binding_pressed,
+    .binding_released = on_sticky_key_binding_released,
+};
+
+static int sticky_key_keycode_state_changed_listener(const struct zmk_event_header *eh) {
+    if (!is_keycode_state_changed(eh)) {
+        return 0;
+    }
+    struct keycode_state_changed *ev = cast_keycode_state_changed(eh);
+    for (int i = 0; i < ZMK_BHV_STICKY_KEY_MAX_HELD; i++) {
+        struct active_sticky_key *sticky_key = &active_sticky_keys[i];
+        if (sticky_key->position == ZMK_BHV_STICKY_KEY_POSITION_NOT_USED) {
+            continue;
+        }
+
+        if (strcmp(sticky_key->config->behavior.behavior_dev, "KEY_PRESS") == 0 &&
+            HID_USAGE_ID(sticky_key->param1) == ev->keycode &&
+            HID_USAGE_PAGE(sticky_key->param1) == ev->usage_page &&
+            SELECT_MODS(sticky_key->param1) == ev->implicit_modifiers) {
+            // don't catch key down events generated by the sticky key behavior itself
+            continue;
+        }
+
+        // If events were queued, the timer event may be queued late or not at all.
+        // Release the sticky key if the timer should've run out in the meantime.
+        if (sticky_key->release_at != 0 && ev->timestamp > sticky_key->release_at) {
+            release_sticky_key_behavior(sticky_key, sticky_key->release_at);
+            if (stop_timer(sticky_key)) {
+                clear_sticky_key(sticky_key);
+            }
+            continue;
+        }
+
+        if (ev->state) { // key down
+            if (sticky_key->modified_key_usage_page != 0 || sticky_key->modified_key_keycode != 0) {
+                // this sticky key is already in use for a keycode
+                continue;
+            }
+            if (sticky_key->timer_started) {
+                stop_timer(sticky_key);
+            }
+            sticky_key->modified_key_usage_page = ev->usage_page;
+            sticky_key->modified_key_keycode = ev->keycode;
+
+        } else { // key up
+            if (sticky_key->timer_started &&
+                sticky_key->modified_key_usage_page == ev->usage_page &&
+                sticky_key->modified_key_keycode == ev->keycode) {
+                release_sticky_key_behavior(sticky_key, ev->timestamp);
+            }
+        }
+    }
+    return 0;
+}
+
+ZMK_LISTENER(behavior_sticky_key, sticky_key_keycode_state_changed_listener);
+ZMK_SUBSCRIPTION(behavior_sticky_key, keycode_state_changed);
+
+void behavior_sticky_key_timer_handler(struct k_work *item) {
+    struct active_sticky_key *sticky_key =
+        CONTAINER_OF(item, struct active_sticky_key, release_timer);
+    if (sticky_key->position == ZMK_BHV_STICKY_KEY_POSITION_NOT_USED) {
+        return;
+    }
+    if (!sticky_key->timer_is_cancelled) {
+        release_sticky_key_behavior(sticky_key, k_uptime_get());
+    }
+    clear_sticky_key(sticky_key);
+}
+
+static int behavior_sticky_key_init(struct device *dev) {
+    static bool init_first_run = true;
+    if (init_first_run) {
+        for (int i = 0; i < ZMK_BHV_STICKY_KEY_MAX_HELD; i++) {
+            k_delayed_work_init(&active_sticky_keys[i].release_timer,
+                                behavior_sticky_key_timer_handler);
+            active_sticky_keys[i].position = ZMK_BHV_STICKY_KEY_POSITION_NOT_USED;
+        }
+    }
+    init_first_run = false;
+    return 0;
+}
+
+struct behavior_sticky_key_data {};
+static struct behavior_sticky_key_data behavior_sticky_key_data;
+
+#define _TRANSFORM_ENTRY(idx, node)                                                                \
+    {                                                                                              \
+        .behavior_dev = DT_LABEL(DT_INST_PHANDLE_BY_IDX(node, bindings, idx)),                     \
+        .param1 = COND_CODE_0(DT_INST_PHA_HAS_CELL_AT_IDX(node, bindings, idx, param1), (0),       \
+                              (DT_INST_PHA_BY_IDX(node, bindings, idx, param1))),                  \
+        .param2 = COND_CODE_0(DT_INST_PHA_HAS_CELL_AT_IDX(node, bindings, idx, param2), (0),       \
+                              (DT_INST_PHA_BY_IDX(node, bindings, idx, param2))),                  \
+    },
+
+#define KP_INST(n)                                                                                 \
+    static struct behavior_sticky_key_config behavior_sticky_key_config_##n = {                    \
+        .behavior = _TRANSFORM_ENTRY(0, n).release_after_ms = DT_INST_PROP(n, release_after_ms),   \
+    };                                                                                             \
+    DEVICE_AND_API_INIT(behavior_sticky_key_##n, DT_INST_LABEL(n), behavior_sticky_key_init,       \
+                        &behavior_sticky_key_data, &behavior_sticky_key_config_##n, APPLICATION,   \
+                        CONFIG_KERNEL_INIT_PRIORITY_DEFAULT, &behavior_sticky_key_driver_api);
+
+DT_INST_FOREACH_STATUS_OKAY(KP_INST)
+
+#endif

app/tests/sticky-keys/1-os-dn-up/events.patterns

@@ -0,0 +1 @@
+s/.*hid_listener_keycode_//p

app/tests/sticky-keys/1-os-dn-up/keycode_events.snapshot

@@ -0,0 +1,4 @@
+pressed: usage_page 0x07 keycode 0x08 mods 0x00
+released: usage_page 0x07 keycode 0x08 mods 0x00
+pressed: usage_page 0x07 keycode 0x04 mods 0x00
+released: usage_page 0x07 keycode 0x04 mods 0x00

app/tests/sticky-keys/1-os-dn-up/native_posix.keymap

@@ -0,0 +1,13 @@
+#include <dt-bindings/zmk/keys.h>
+#include <behaviors.dtsi>
+#include <dt-bindings/zmk/kscan-mock.h>
+#include "../behavior_keymap.dtsi"
+
+&kscan {
+	events = <
+		ZMK_MOCK_PRESS(0,0,10) 
+		ZMK_MOCK_RELEASE(0,0,1200) 
+		ZMK_MOCK_PRESS(1,0,10)
+		ZMK_MOCK_RELEASE(1,0,10)
+	>;
+};

app/tests/sticky-keys/2-os-dn-up-kcdn-kcup/events.patterns

@@ -0,0 +1 @@
+s/.*hid_listener_keycode_//p

app/tests/sticky-keys/2-os-dn-up-kcdn-kcup/keycode_events.snapshot

@@ -0,0 +1,4 @@
+pressed: usage_page 0x07 keycode 0x08 mods 0x00
+pressed: usage_page 0x07 keycode 0x04 mods 0x00
+released: usage_page 0x07 keycode 0x08 mods 0x00
+released: usage_page 0x07 keycode 0x04 mods 0x00

app/tests/sticky-keys/2-os-dn-up-kcdn-kcup/native_posix.keymap

@@ -0,0 +1,13 @@
+#include <dt-bindings/zmk/keys.h>
+#include <behaviors.dtsi>
+#include <dt-bindings/zmk/kscan-mock.h>
+#include "../behavior_keymap.dtsi"
+
+&kscan {
+	events = <
+		ZMK_MOCK_PRESS(0,0,10) 
+		ZMK_MOCK_RELEASE(0,0,10) 
+		ZMK_MOCK_PRESS(1,0,10)
+		ZMK_MOCK_RELEASE(1,0,10)
+	>;
+};

app/tests/sticky-keys/3a-os-dn-kcdn-kcup-up/events.patterns

@@ -0,0 +1 @@
+s/.*hid_listener_keycode_//p

app/tests/sticky-keys/3a-os-dn-kcdn-kcup-up/keycode_events.snapshot

@@ -0,0 +1,4 @@
+pressed: usage_page 0x07 keycode 0x08 mods 0x00
+pressed: usage_page 0x07 keycode 0x04 mods 0x00
+released: usage_page 0x07 keycode 0x04 mods 0x00
+released: usage_page 0x07 keycode 0x08 mods 0x00

app/tests/sticky-keys/3a-os-dn-kcdn-kcup-up/native_posix.keymap

@@ -0,0 +1,13 @@
+#include <dt-bindings/zmk/keys.h>
+#include <behaviors.dtsi>
+#include <dt-bindings/zmk/kscan-mock.h>
+#include "../behavior_keymap.dtsi"
+
+&kscan {
+	events = <
+		ZMK_MOCK_PRESS(0,0,10) 
+		ZMK_MOCK_PRESS(1,0,10)
+		ZMK_MOCK_RELEASE(1,0,10)
+		ZMK_MOCK_RELEASE(0,0,10) 
+	>;
+};

app/tests/sticky-keys/3b-os-dn-kcdn-up-kcup/events.patterns

@@ -0,0 +1 @@
+s/.*hid_listener_keycode_//p

app/tests/sticky-keys/3b-os-dn-kcdn-up-kcup/keycode_events.snapshot

@@ -0,0 +1,4 @@
+pressed: usage_page 0x07 keycode 0x08 mods 0x00
+pressed: usage_page 0x07 keycode 0x04 mods 0x00
+released: usage_page 0x07 keycode 0x08 mods 0x00
+released: usage_page 0x07 keycode 0x04 mods 0x00

app/tests/sticky-keys/3b-os-dn-kcdn-up-kcup/native_posix.keymap

@@ -0,0 +1,13 @@
+#include <dt-bindings/zmk/keys.h>
+#include <behaviors.dtsi>
+#include <dt-bindings/zmk/kscan-mock.h>
+#include "../behavior_keymap.dtsi"
+
+&kscan {
+	events = <
+		ZMK_MOCK_PRESS(0,0,10) 
+		ZMK_MOCK_PRESS(1,0,10)
+		ZMK_MOCK_RELEASE(0,0,10) 
+		ZMK_MOCK_RELEASE(1,0,10)
+	>;
+};

app/tests/sticky-keys/4-os-dn-up-kcdn-timer-kcup/events.patterns

@@ -0,0 +1 @@
+s/.*hid_listener_keycode_//p

app/tests/sticky-keys/4-os-dn-up-kcdn-timer-kcup/keycode_events.snapshot

@@ -0,0 +1,4 @@
+pressed: usage_page 0x07 keycode 0x08 mods 0x00
+pressed: usage_page 0x07 keycode 0x04 mods 0x00
+released: usage_page 0x07 keycode 0x08 mods 0x00
+released: usage_page 0x07 keycode 0x04 mods 0x00

app/tests/sticky-keys/4-os-dn-up-kcdn-timer-kcup/native_posix.keymap

@@ -0,0 +1,13 @@
+#include <dt-bindings/zmk/keys.h>
+#include <behaviors.dtsi>
+#include <dt-bindings/zmk/kscan-mock.h>
+#include "../behavior_keymap.dtsi"
+
+&kscan {
+	events = <
+		ZMK_MOCK_PRESS(0,0,10) 
+		ZMK_MOCK_RELEASE(0,0,800) 
+		ZMK_MOCK_PRESS(1,0,400)
+		ZMK_MOCK_RELEASE(1,0,10)
+	>;
+};

app/tests/sticky-keys/5-os-kcdn-dn-kcup-up/events.patterns

@@ -0,0 +1 @@
+s/.*hid_listener_keycode_//p

app/tests/sticky-keys/5-os-kcdn-dn-kcup-up/keycode_events.snapshot

@@ -0,0 +1,4 @@
+pressed: usage_page 0x07 keycode 0x04 mods 0x00
+pressed: usage_page 0x07 keycode 0x08 mods 0x00
+released: usage_page 0x07 keycode 0x04 mods 0x00
+released: usage_page 0x07 keycode 0x08 mods 0x00

app/tests/sticky-keys/5-os-kcdn-dn-kcup-up/native_posix.keymap

@@ -0,0 +1,13 @@
+#include <dt-bindings/zmk/keys.h>
+#include <behaviors.dtsi>
+#include <dt-bindings/zmk/kscan-mock.h>
+#include "../behavior_keymap.dtsi"
+
+&kscan {
+	events = <
+		ZMK_MOCK_PRESS(1,0,10)
+		ZMK_MOCK_PRESS(0,0,10) 
+		ZMK_MOCK_RELEASE(1,0,10)
+		ZMK_MOCK_RELEASE(0,0,1100) 
+	>;
+};

app/tests/sticky-keys/7-os-dn-up-kc1dn-kc2dn-kc1up-kc2up/events.patterns

@@ -0,0 +1 @@
+s/.*hid_listener_keycode_//p

app/tests/sticky-keys/7-os-dn-up-kc1dn-kc2dn-kc1up-kc2up/keycode_events.snapshot

@@ -0,0 +1,6 @@
+pressed: usage_page 0x07 keycode 0x08 mods 0x00
+pressed: usage_page 0x07 keycode 0x04 mods 0x00
+pressed: usage_page 0x07 keycode 0x05 mods 0x00
+released: usage_page 0x07 keycode 0x08 mods 0x00
+released: usage_page 0x07 keycode 0x04 mods 0x00
+released: usage_page 0x07 keycode 0x05 mods 0x00

app/tests/sticky-keys/7-os-dn-up-kc1dn-kc2dn-kc1up-kc2up/native_posix.keymap

@@ -0,0 +1,15 @@
+#include <dt-bindings/zmk/keys.h>
+#include <behaviors.dtsi>
+#include <dt-bindings/zmk/kscan-mock.h>
+#include "../behavior_keymap.dtsi"
+
+&kscan {
+	events = <
+		ZMK_MOCK_PRESS(0,0,10) 
+		ZMK_MOCK_RELEASE(0,0,10) 
+		ZMK_MOCK_PRESS(1,0,10)
+		ZMK_MOCK_PRESS(1,1,10)
+		ZMK_MOCK_RELEASE(1,0,100)
+		ZMK_MOCK_RELEASE(1,1,100)
+	>;
+};

app/tests/sticky-keys/behavior_keymap.dtsi

@@ -0,0 +1,22 @@
+#include <dt-bindings/zmk/keys.h>
+#include <behaviors.dtsi>
+#include <dt-bindings/zmk/kscan-mock.h>
+
+/ {
+	keymap {
+		compatible = "zmk,keymap";
+		label ="Default keymap";
+
+		default_layer {
+			bindings = <
+				&sk E &mo 1
+				&kp A &kp B>;
+		};
+
+		lower_layer {
+			bindings = <
+				&sk LEFT_CONTROL &kp X
+				&kp Y  &kp Z>;
+		};
+	};
+};