add src/button.h and src/button.c

- this relates to the issue #8

src/button.c

@@ -0,0 +1,74 @@
+/*
+ * This file is part of the 'Yet another gauge' project.
+ *
+ * Copyright (C) 2018 Ivan Dyachenko <[email protected]>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdlib.h>
+
+#include <subject.h>
+
+#include <libopencm3/stm32/gpio.h>
+
+#include "button.h"
+
+struct button_t {
+  uint16_t gpio_pin;
+  uint32_t gpio_port;
+
+  enum rcc_periph_clken clken;
+
+  subject_t *subject;
+};
+
+button_t *button_new(enum rcc_periph_clken clken, uint16_t gpio_pin, uint32_t gpio_port) {
+  // Enable the clock on particular peripheral
+  rcc_periph_clock_enable(clken);
+
+  // Enable the peripheral clock
+  gpio_mode_setup(gpio_port, GPIO_MODE_INPUT, GPIO_PUPD_PULLDOWN, gpio_pin);
+
+  button_t *button = malloc(sizeof(button_t));
+
+  button->gpio_pin = gpio_pin;
+  button->gpio_port = gpio_port;
+
+  button->clken = clken;
+
+  button->subject = subject_new();
+
+  return button;
+}
+
+void button_free(button_t *button) {
+  if (button != NULL) {
+    subject_delete(button->subject);
+
+    free(button);
+  }
+}
+
+void button_attach(button_t *button, const observer_t *observer) {
+  subject_attach(button->subject, observer);
+}
+
+void button_detach(button_t *button, const observer_t *observer) {
+  subject_detach(button->subject, observer);
+}
+
+void button_notify(const button_t *button, int argc, const void *argv[]) {
+  subject_notify(button->subject, argc, argv);
+}

src/button.h

@@ -0,0 +1,68 @@
+/*
+ * This file is part of the 'Yet another gauge' project.
+ *
+ * Copyright (C) 2018 Ivan Dyachenko <[email protected]>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef YET_ANOTHER_GAUGE__LOOP_CALIBRATOR__BUTTON_H
+#define YET_ANOTHER_GAUGE__LOOP_CALIBRATOR__BUTTON_H
+
+#include <stdint.h>
+
+#include <observer.h>
+
+#include <libopencm3/stm32/rcc.h>
+
+typedef struct button_t button_t;
+
+/**
+ * @brief Allocate a struct button_t, intended to be used as an button
+ * @param [in] clken
+ * @param [in] gpio_pin
+ * @param [in] gpio_port
+ * @return The button
+ */
+button_t *button_new(enum rcc_periph_clken clken, uint16_t gpio_pin, uint32_t gpio_port);
+
+/**
+ * @brief Free the memory for the given button
+ * @param [in,out] button
+ */
+void button_free(button_t *);
+
+/**
+ * @brief Attach the observer to a button
+ * @param [in,out] button
+ * @param [in] observer
+ */
+void button_attach(button_t *, const observer_t *);
+
+/**
+ * @brief Detach the given observer from the button
+ * @param [in,out] button
+ * @param [in] observer
+ */
+void button_detach(button_t *, const observer_t *);
+
+/**
+ * @brief Send a notification to all the observers of the button
+ * @param [in] button
+ * @param [in] argc
+ * @param [in] argv
+ */
+void button_notify(const button_t *, int argc, const void *argv[]);
+
+#endif // YET_ANOTHER_GAUGE__LOOP_CALIBRATOR__BUTTON_H