Merge pull request #433 from LudwigOrtmann/lifo_debug

lifo debug and reset

core/include/lifo.h

@@ -11,17 +11,52 @@
  * @{
  *
  * @file        lifo.h
- * @brief       LIFO buffer API
+ * @brief       LIFO buffer API, read long description carefully
+ * @author      probably Kaspar Schleiser
  *
- * @author      unknwon
+ * @long        This LIFO implementation very efficiently handles
+ *              integer values. The caveat is that it can only handle
+ *              values between 0 and its own size -1. Also it can only
+ *              handle up to one element of each value. If you insert
+ *              a value twice the LIFO will break.
  */
 
 #ifndef __LIFO_H
 #define __LIFO_H
 
+/**
+ * @brief:  check if the given lifo is empty
+ * @return: true if empty, false otherwise
+ */
 int lifo_empty(int *array);
+
+/**
+ * @brief:           initialize a lifo array
+ *
+ * @param array:     an array of int of size n+1
+ * @param n:         maximum integer value the lifo is able to store
+ */
 void lifo_init(int *array, int n);
+
+/**
+ * @brief:          insert an element into the lifo
+ *
+ * @param array:    an integer array of least i+1 size that does not
+ *                  already contain i 
+ * @param i:        the integer value to store, between 0 and the size
+ *                  of the array -1, must not be stored already
+ *
+ */
 void lifo_insert(int *array, int i);
+
+/**
+ * @brief:          extract the least recently inserted element from the lifo
+ * 
+ * @param array:    an integer array
+ *
+ * @return:         -1 if the lifo is empty, the least recently
+ *                  inserted element otherwise
+ */
 int lifo_get(int *array);
 
 /** @} */

core/lifo.c

@@ -9,18 +9,17 @@
 /**
  * @ingroup     core_util
  * @{
- *
  * @file        lifo.c
  * @brief       LIFO buffer implementation
- *
- * @file        lifo.c
- * @brief       LIFO buffer implementation
- * @author      unknown
+ * @author      probably Kaspar Schleiser
  * @}
  */
 
 #include "lifo.h"
 
+#define ENABLE_DEBUG (0)
+#include "debug.h"
+
 int lifo_empty(int *array)
 {
     return array[0] == -1;
@@ -28,6 +27,7 @@ int lifo_empty(int *array)
 
 void lifo_init(int *array, int n)
 {
+    DEBUG("lifo_init(%i)\n", n);
     for (int i = 0; i <= n; i++) {
         array[i] = -1;
     }
@@ -35,19 +35,36 @@ void lifo_init(int *array, int n)
 
 void lifo_insert(int *array, int i)
 {
+    DEBUG("lifo_insert(%i)\n", i);
+
     int index = i + 1;
+
+#if DEVELHELP
+    if ((array[index] != -1) && (array[0] != -1)) {
+        printf("lifo_insert: overwriting array[%i] == %i with %i\n\n\n\t\tThe lifo is broken now.\n\n\n", index, array[index], array[0]);
+    }
+#endif
+
     array[index] = array[0];
     array[0] = i;
 }
 
 int lifo_get(int *array)
 {
+    DEBUG("lifo_get\n");
     int head = array[0];
 
     if (head != -1) {
         array[0] = array[head + 1];
     }
 
+#if DEVELHELP
+    /* make sure a double insert does not result in an infinite
+     * resource of values */
+    array[head+1] = -1;
+#endif
+
+    DEBUG("lifo_get: returning %i\n", head);
     return head;
 }
 
@@ -60,12 +77,20 @@ int main()
 
     lifo_init(array, 4);
 
-    lifo_insert(array, 0);
-    lifo_insert(array, 1);
     lifo_insert(array, 2);
+    lifo_insert(array, 1);
+    lifo_insert(array, 3);
+    lifo_insert(array, 0);
     lifo_insert(array, 3);
     printf("get: %i\n", lifo_get(array));
-
+    printf("get: %i\n", lifo_get(array));
+    printf("get: %i\n", lifo_get(array));
+    printf("get: %i\n", lifo_get(array));
+    printf("get: %i\n", lifo_get(array));
+    printf("get: %i\n", lifo_get(array));
+    printf("get: %i\n", lifo_get(array));
+    printf("get: %i\n", lifo_get(array));
+    printf("get: %i\n", lifo_get(array));
 
     return 0;
 }