add buffer_8 code

buffer_8/buffer.c

@@ -0,0 +1,60 @@
+#include "buffer.h"
+// implementation for a FIFO-buffer with ints
+// this very simple FIFO-buffer can only hold one int
+#define FIFO_SIZE 8
+
+// shared variables within this file
+static int FIFO[FIFO_SIZE];
+static unsigned int FIFO_count = 0;
+
+// read and write pointers
+unsigned int FIFO_write_p = 0;
+unsigned int FIFO_read_p = 0;
+
+/** incrementPointer
+ *
+ * add one and rotates if it overflows the buffersize
+ */
+unsigned int incrementPointer(unsigned int p)
+{
+    p++;
+    if (p == FIFO_SIZE)
+    {
+        p = 0;
+    }
+    return p;
+}
+
+bool buffer_put(int i)
+{
+    bool notFull = !buffer_is_full();
+    if (notFull)
+    {
+        FIFO[FIFO_write_p] = i;
+        FIFO_count++;
+        FIFO_write_p = incrementPointer(FIFO_write_p);
+    }
+    return notFull;
+}
+
+bool buffer_get(int *p)
+{
+    bool notEmpty = !buffer_is_empty();
+    if (notEmpty)
+    {
+        *p = FIFO[FIFO_read_p];
+        FIFO_count--;
+        FIFO_read_p = incrementPointer(FIFO_read_p);
+    }
+    return notEmpty;
+}
+
+bool buffer_is_full(void)
+{
+    return (FIFO_count >= FIFO_SIZE);
+}
+
+bool buffer_is_empty(void)
+{
+    return (FIFO_count <= 0);
+}

buffer_8/buffer.h

@@ -0,0 +1,22 @@
+#ifndef _HR_BroJZ_buffer_
+#define _HR_BroJZ_buffer_
+
+#include <stdbool.h>
+
+// interface for a buffer with int's
+
+// put value i in buffer if buffer is not full
+// returns true on success or false otherways
+extern bool buffer_put(int i);
+
+// get value from buffer and writes it to *p if buffer not empty
+// returns true on success or false otherways
+extern bool buffer_get(int *p);
+
+// returns true when buffer is full or false otherways
+extern bool buffer_is_full(void);
+
+// returns true when buffer is empty or false otherways
+extern bool buffer_is_empty(void);
+
+#endif