Starting Point

include/lib/ringbuffer.h

@@ -0,0 +1,89 @@
+#ifndef RINGBUFFER_H_
+#define RINGBUFFER_H_
+
+/**
+ * \brief Ringbuffer Datenstruktur
+ * \file ringbuffer.h
+ *
+ * Diese Datei ist eine Hilfestellung für Aufgabe 2.
+ * Sie erspart euch den Aufwand, selber einen Ringbuffer zu implementieren.
+ */
+
+struct ring_buff {
+	unsigned int head;
+	unsigned int tail;
+	unsigned int size;
+	unsigned int mask;
+	char	    *buffer;
+};
+
+/**
+ * \brief Überprüft ob eine positive Zahl eine Zweierpotenz ist
+ *
+ * Beispiel: (0b100 & 0b011) == 0b000.
+ */
+#define is_power_of_two(val) (((val) & ((val) - 1)) == 0)
+
+/**
+ * \brief Macro um einen Ringbuffer zu erstellen
+ * \param name Bezeichnung des Buffers
+ * \param size Größe des Buffers
+ *
+ */
+#define create_ringbuffer(name, size)                                                        \
+	static_assert((size) >= 1, "Size of Ringbuffer has to be at least 1");               \
+	static_assert(is_power_of_two(size), "Size of Ringbuffer has to be a power of 2");   \
+	static char			  _b_##name[size];                                   \
+	static struct ring_buff		  _##name = { 0, 0, (size), (size) - 1, _b_##name }; \
+	static volatile struct ring_buff *name	  = &_##name
+
+[[nodiscard]] static bool buff_is_empty(volatile struct ring_buff *b)
+{
+	return b->head == b->tail;
+}
+
+[[nodiscard]] static bool buff_is_full(volatile struct ring_buff *b)
+{
+	return ((b->tail & b->mask) == (b->head & b->mask)) && !buff_is_empty(b);
+}
+
+static bool buff_putc(volatile struct ring_buff *b, char c)
+{
+	if (buff_is_full(b)) {
+		return true;
+	}
+
+	b->buffer[b->head & b->mask] = c;
+	b->head++;
+
+	return false;
+}
+
+static char buff_getc(volatile struct ring_buff *b)
+{
+	while (buff_is_empty(b)) {
+	}
+
+	char c = b->buffer[b->tail & b->mask];
+	b->tail++;
+
+	return c;
+}
+
+[[nodiscard, maybe_unused]] static char buff_peekc(volatile struct ring_buff *b)
+{
+	while (buff_is_empty(b)) {
+	}
+
+	return b->buffer[b->tail & b->mask];
+}
+
+[[nodiscard, maybe_unused]] static char buff_peekc_last(volatile struct ring_buff *b)
+{
+	while (buff_is_empty(b)) {
+	}
+
+	return b->buffer[(b->head - 1) & b->mask];
+}
+
+#endif