Added ralloc function.

.idea/vcs.xml

@@ -1,5 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
+  <component name="GitSharedSettings">
+    <option name="FORCE_PUSH_PROHIBITED_PATTERNS">
+      <list />
+    </option>
+  </component>
   <component name="VcsDirectoryMappings">
     <mapping directory="" vcs="Git" />
   </component>

main.c

@@ -4,6 +4,7 @@
 
 #define ALIGN4(s) (((((s)-1)>>2)<<2)+4)
 #define BLOCK_SIZE sizeof(struct block)
+#define MINIMUM_BLOCK_SIZE  16
 
 /// The memory block's header.
 struct block
@@ -22,6 +23,10 @@ struct block* last = NULL;
 /// @returns The new memory block.
 struct block* extend_heap(size_t s)
 {
+	// Ensure the allocated size is at least the minimum block size
+	if (s < MINIMUM_BLOCK_SIZE)
+		s = MINIMUM_BLOCK_SIZE;
+
 	struct block* b = sbrk(0);
 
 	if (sbrk(BLOCK_SIZE + s) == (void*)-1)
@@ -52,6 +57,10 @@ struct block* find_first(size_t s)
 	return current;
 }
 
+/// Fragments an existing free memory block into the given size.
+/// @param [in] in The memory block to fragment.
+/// @param [in] s The size of the new memory block.
+/// @returns The new memory block.
 struct block* fragment_block(struct block* in, size_t s)
 {
 	size_t totalSize = BLOCK_SIZE + s;
@@ -75,19 +84,19 @@ void* malloc(size_t size)
 {
 	struct block* b;
 
-	size_t alignedSize = ALIGN4(size);
+	size = ALIGN4(size);
 
 	if (first)
 	{
-		b = find_first(alignedSize);
+		b = find_first(size);
 		if (!b)
-			b = extend_heap(alignedSize);
+			b = extend_heap(size);
-		else if (b->size > BLOCK_SIZE + alignedSize)
+		else if (b->size > BLOCK_SIZE + size)
-			b = fragment_block(b, alignedSize);
+			b = fragment_block(b, size);
 	}
 	else
 	{
-		b = extend_heap(alignedSize);
+		b = extend_heap(size);
 		if (!b)
 			return NULL;
 
@@ -97,6 +106,26 @@ void* malloc(size_t size)
 	return b + 1;
 }
 
+void* realloc(void* ptr, size_t new_size)
+{
+	if (!ptr)
+		return malloc(new_size);
+
+	if (!new_size)
+		return NULL;
+
+	struct block* b = (struct block*)ptr - 1;
+	if (b->free)
+		return NULL;
+
+	if (b->size == new_size)
+		return ptr;
+	else if (b->size > BLOCK_SIZE + new_size)
+		return fragment_block(b, new_size) + 1;
+
+	return NULL;
+}
+
 /// Will flag the provided memory as free and will defragment other blocks adjacent to it.
 /// @param [in] ptr The memory to flag as free.
 /// @note If all data after the provided memory is free, it will reduce the heap size.