feat: Add WPM calculator and display widget

app/src/wpm.c

@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include <device.h>
+#include <init.h>
+#include <kernel.h>
+
+#include <logging/log.h>
+
+LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
+
+#include <zmk/event_manager.h>
+#include <zmk/events/wpm_state_changed.h>
+#include <zmk/events/keycode_state_changed.h>
+
+#include <zmk/wpm.h>
+
+#define WPM_UPDATE_INTERVAL_SECONDS 1
+#define WPM_RESET_INTERVAL_SECONDS 5
+
+// See https://en.wikipedia.org/wiki/Words_per_minute
+// "Since the length or duration of words is clearly variable, for the purpose of measurement of
+// text entry, the definition of each "word" is often standardized to be five characters or
+// keystrokes long in English"
+#define CHARS_PER_WORD 5.0
+
+static uint8_t wpm_state = -1;
+static uint8_t last_wpm_state;
+static uint8_t wpm_update_counter;
+static uint32_t key_pressed_count;
+
+int zmk_wpm_get_state() { return wpm_state; }
+
+int wpm_event_listener(const zmk_event_t *eh) {
+    const struct zmk_keycode_state_changed *ev = as_zmk_keycode_state_changed(eh);
+    if (ev) {
+        // count only key up events
+        if (!ev->state) {
+            key_pressed_count++;
+            LOG_DBG("key_pressed_count %d keycode %d", key_pressed_count, ev->keycode);
+        }
+    }
+    return 0;
+}
+
+void wpm_work_handler(struct k_work *work) {
+    wpm_update_counter++;
+    wpm_state = (key_pressed_count / CHARS_PER_WORD) /
+                (wpm_update_counter * WPM_UPDATE_INTERVAL_SECONDS / 60.0);
+
+    if (last_wpm_state != wpm_state) {
+        LOG_DBG("Raised WPM state changed %d wpm_update_counter %d", wpm_state, wpm_update_counter);
+
+        ZMK_EVENT_RAISE(
+            new_zmk_wpm_state_changed((struct zmk_wpm_state_changed){.state = wpm_state}));
+
+        last_wpm_state = wpm_state;
+    }
+
+    if (wpm_update_counter >= WPM_RESET_INTERVAL_SECONDS) {
+        wpm_update_counter = 0;
+        key_pressed_count = 0;
+    }
+}
+
+K_WORK_DEFINE(wpm_work, wpm_work_handler);
+
+void wpm_expiry_function() { k_work_submit(&wpm_work); }
+
+K_TIMER_DEFINE(wpm_timer, wpm_expiry_function, NULL);
+
+int wpm_init() {
+    wpm_state = 0;
+    wpm_update_counter = 0;
+    k_timer_start(&wpm_timer, K_SECONDS(WPM_UPDATE_INTERVAL_SECONDS),
+                  K_SECONDS(WPM_UPDATE_INTERVAL_SECONDS));
+    return 0;
+}
+
+ZMK_LISTENER(wpm, wpm_event_listener);
+ZMK_SUBSCRIPTION(wpm, zmk_keycode_state_changed);
+
+SYS_INIT(wpm_init, APPLICATION, CONFIG_APPLICATION_INIT_PRIORITY);