Added block functions which are required for navigation on data layout level.

private-include/block_header.h

@@ -77,6 +77,20 @@ void set_size(void *ptr, size_t size);
 void set_requested_size(void *ptr, size_t size);
 
 /**
+ * Mark the memory block as used
+ *
+ * \param ptr 	The pointer to the data part of the memory block.
+ */
+void mark_used(void *ptr);
+
+/**
+ * Mark the memory block as free
+ *
+ * \param ptr 	The pointer to the data part of the memory block.
+ */
+void mark_free(void *ptr);
+
+/**
  * Set the availability and the size of the previous memory block's data
  *
  * \param ptr 		The pointer to the data part of the current memory block.
@@ -107,6 +121,8 @@ bool is_previous_free(void *ptr);
  */
 size_t get_previous_size(void *ptr);
 
+size_t get_previous_size_availability(void *ptr);
+
 /**
  * Get the previous memory block (in the memory space)
  *

src/block_header.c

@@ -31,12 +31,24 @@ void set_requested_size(void *ptr, size_t size) {
     get_header(ptr)->requested_size = size;
 }
 
+void mark_used(void *ptr) {
+    get_header(ptr)->size |= 1;
+}
+
+void mark_free(void *ptr) {
+    get_header(ptr)->size &= (~ 0x1);
+}
+
 void set_next(void *ptr, void *next_block) {
     get_header(ptr)->next = next_block;
 }
 
 bool is_previous_free(void *ptr) {
-    return (bool) (get_header(ptr)->previous_size & 1);
+    if (get_header(ptr)->previous_size & (size_t) 1) {
+        return false;
+    } else {
+        return true;
+    }
 }
 
 void set_previous_size_availability(void *ptr, size_t previous_size_availability) {
@@ -47,15 +59,19 @@ size_t get_previous_size(void *ptr) {
     return get_header(ptr)->previous_size >> 1;
 }
 
+size_t get_previous_size_availability(void *ptr) {
+    return get_header(ptr)->previous_size;
+}
+
 void * get_previous(void *ptr) {
-    return (void *) ((char *) ptr - get_previous_size(ptr));
+    return (void *) ((char *) ptr - HEADER_SIZE - get_previous_size(ptr));
 }
 
 void remove_block(void *block, void *starting_node) {
 
     void *current_node, *previous_node;
 
-    // Traverse a list starting from the starting node until block is found.
+    /* Traverse a list starting from the starting node until block is found. */
     for(current_node = starting_node; current_node != NULL; 
             current_node = get_next(current_node)) {
         if(current_node == block) {