Refactor Rust drivers for strict idiomatic documentation and 8-line enforcement

drivers/0x03_button/0x03_button.c

@@ -0,0 +1,79 @@
+/**
+ * @file 0x03_button.c
+ * @brief Button demonstration: debounced press mirrors to LED + UART report
+ * @author Kevin Thomas
+ * @date 2025
+ *
+ * MIT License
+ *
+ * Copyright (c) 2025 Kevin Thomas
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * -----------------------------------------------------------------------------
+ *
+ * Demonstrates GPIO input using the button driver (button.h / button.c).
+ * The onboard LED mirrors the button state and every edge transition is
+ * reported over UART.
+ *
+ * Wiring:
+ *   GPIO15 -> One leg of push button
+ *   GND    -> Other leg of push button
+ *   GPIO25 -> Onboard LED (no external wiring needed)
+ */
+
+#include <stdio.h>
+#include "pico/stdlib.h"
+#include "button.h"
+
+/** @brief GPIO pin for the push-button input */
+#define BUTTON_PIN  15
+/** @brief GPIO pin for the indicator LED */
+#define LED_PIN     25
+/** @brief Button debounce delay in milliseconds */
+#define DEBOUNCE_MS 20
+
+/**
+ * @brief Poll button state and report edge transitions over UART
+ *
+ * Reads the debounced button state, mirrors it to the LED, and prints
+ * a message when the state changes from the previous reading.
+ *
+ * @param last_state Pointer to the stored previous button state
+ */
+static void poll_button(bool *last_state) {
+    bool pressed = button_is_pressed(BUTTON_PIN);
+    button_led_set(LED_PIN, pressed);
+    if (pressed != *last_state) {
+        printf("Button: %s\r\n", pressed ? "PRESSED" : "RELEASED");
+        *last_state = pressed;
+    }
+}
+
+int main(void) {
+    stdio_init_all();
+    button_init(BUTTON_PIN, DEBOUNCE_MS);
+    button_led_init(LED_PIN);
+    printf("Button driver initialized: button=GPIO%d  led=GPIO%d\r\n", BUTTON_PIN, LED_PIN);
+    bool last_state = false;
+    while (true) {
+        poll_button(&last_state);
+        sleep_ms(10);
+    }
+}