1 files changed, 123 insertions, 0 deletions
diff --git a/src/c/config.c b/src/c/config.c
new file mode 100644
index 0000000..0791b85
--- /dev/null
+++ b/src/c/config.c
@@ -0,0 +1,123 @@
+/* Copyright (C) 2026 Reiner Herrmann
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <pebble.h>
+#include "config.h"
+#include "metronome.h"
+
+struct Configuration {
+	uint8_t version;
+	uint16_t bpm;
+	uint8_t beats;
+	uint8_t volume;
+	uint8_t beat_indicators;
+} __attribute__((__packed__));
+
+#define SETTINGS_KEY 1
+#define CONFIG_VERSION 1
+
+static struct Configuration configuration;
+
+static void config_persist() {
+	persist_write_data(SETTINGS_KEY, &configuration, sizeof(configuration));
+}
+
+static void config_load_defaults() {
+	configuration.version = CONFIG_VERSION;
+	configuration.bpm = 90;
+	configuration.beats = 4;
+	configuration.volume = 100;
+	configuration.beat_indicators = 0xff;
+}
+
+static void config_load() {
+	config_load_defaults();
+
+	/* buffer remains unchanged if no data is persisted */
+	persist_read_data(SETTINGS_KEY, &configuration, sizeof(configuration));
+
+	if (configuration.version != CONFIG_VERSION) {
+		/* unknown persisted configuration format */
+		config_load_defaults();
+	}
+}
+
+static void config_inbox_received_handler(DictionaryIterator *iter, void *context) {
+	struct Configuration new_configuration;
+	memcpy(&new_configuration, &configuration, sizeof(configuration));
+
+	Tuple *bpm_tuple = dict_find(iter, MESSAGE_KEY_bpm);
+	if (bpm_tuple) {
+		int32_t bpm = bpm_tuple->value->int32;
+		configuration.bpm = (uint16_t) bpm;
+	}
+
+	Tuple *beats_tuple = dict_find(iter, MESSAGE_KEY_beats);
+	if (beats_tuple) {
+		int32_t beats = beats_tuple->value->int32;
+		configuration.beats = (uint8_t) beats;
+	}
+
+	Tuple *volume_tuple = dict_find(iter, MESSAGE_KEY_volume);
+	if (volume_tuple) {
+		int32_t volume = volume_tuple->value->int32;
+		configuration.volume = (uint8_t) volume;
+	}
+
+	const int num_beat_indicators = 3;
+	for (int i=0; i<num_beat_indicators; i++) {
+		Tuple *beat_indicator = dict_find(iter, MESSAGE_KEY_beat_indicators + i);
+		if (beat_indicator) {
+			bool val = beat_indicator->value->uint8;
+			/* clear bit */
+			configuration.beat_indicators &= ~(1 << i);
+			/* set value into bit */
+			configuration.beat_indicators |= (val << i);
+		}
+	}
+
+	if (memcmp(&new_configuration, &configuration, sizeof(configuration)) != 0) {
+		/* only persist if something changed */
+		config_persist();
+
+		update_display();
+	}
+}
+
+void config_init() {
+	config_load();
+
+	app_message_register_inbox_received(config_inbox_received_handler);
+	app_message_open(128, 128);
+}
+
+void config_deinit() {
+	app_message_deregister_callbacks();
+}
+
+uint16_t config_get_bpm() {
+	return configuration.bpm;
+}
+
+void config_set_bpm(uint16_t bpm) {
+	configuration.bpm = bpm;
+	config_persist();
+}
+
+uint8_t config_get_beats() {
+	return configuration.beats;
+}
+
+void config_set_beats(uint8_t beats) {
+	configuration.beats = beats;
+	config_persist();
+}
+
+uint8_t config_get_volume() {
+	return configuration.volume;
+}
+
+bool config_is_indicator_enabled(enum BeatIndicator indicator) {
+	return configuration.beat_indicators & (1 << indicator);
+}