style: enforce coding standard — headers, @brief on #define, Doxygen on statics, remove _ prefix, max 8 lines per function

0x0008_unitialized-variables/0x0008_unitialized-variables.c

@@ -1,23 +1,68 @@
+/**
+ * @file 0x0008_unitialized-variables.c
+ * @brief Uninitialized variables: demonstrate undefined behavior with printf
+ * @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 the danger of uninitialized variables. Prints the value of an
+ * uninitialized uint8_t over UART while blinking an LED on GPIO16.
+ *
+ * Wiring:
+ *   GPIO16 -> LED anode (with current-limiting resistor to GND)
+ */
+
 #include <stdio.h>
 #include "pico/stdlib.h"
 
-#define LED_PIN 16 
+/** @brief GPIO pin number for the LED */
+#define LED_PIN 16
+
+/**
+ * @brief Toggle LED and print uninitialized variable value
+ *
+ * @details Blinks the LED on and off with a 500ms delay between each
+ *          transition and prints the age variable each cycle.
+ *
+ * @param age value to print (uninitialized in this demo)
+ */
+static void blink_and_print(uint8_t age) {
+    printf("age: %d\r\n", age);
+    gpio_put(LED_PIN, 1);
+    sleep_ms(500);
+    gpio_put(LED_PIN, 0);
+    sleep_ms(500);
+}
 
 int main(void) {
     uint8_t age;
-
     stdio_init_all();
-
     gpio_init(LED_PIN);
     gpio_set_dir(LED_PIN, GPIO_OUT);
-
     while (true) {
-        printf("age: %d\r\n", age);
-
-        gpio_put(LED_PIN, 1);
-        sleep_ms(500);
-
-        gpio_put(LED_PIN, 0);
-        sleep_ms(500);
+        blink_and_print(age);
     }
 }