malloc: defined get_next_chunk, get_prev_chunk, and align

include/gc_malloc.h

@@ -12,7 +12,7 @@
 #define MIN 3 /* Minimum number of 8-byte segments for data in a chunk */
 
 /*
- * Metadata for allocated memory
+ * Metadata and user data for allocated memory
  *
  * footer: user data for previous chunk
  * size: size of chunk in bytes
@@ -30,6 +30,18 @@ struct gc_chunk {
 	struct gc_chunk *prev;
 };
 
+// Gets a pointer to the next chunk
+struct gc_chunk *get_next_chunk(struct gc_chunk *curr);
+
+// Gets a pointer to the previous chunk, ensuring that current can be coalesced
+struct gc_chunk *get_prev_chunk(struct gc_chunk *curr);
+
+// Updates chunk footer information
+void set_footer(struct gc_chunk *curr);
+
+// Gets footer information for the current chunk
+int get_footer(struct gc_chunk *curr);
+
 // Performs allocations of SIZE bytes
 void *gc_malloc(size_t size);
 

src/gc_malloc.c

@@ -1,4 +1,5 @@
 #include <assert.h>
+#include <stdint.h>
 #include <sys/mman.h>
 
 #include "gc_malloc.h"
@@ -14,3 +15,28 @@ static inline struct gc_chunk *magic(void *mem)
 {
 	return (struct gc_chunk *)((uint64_t *)mem - MAGIC);
 }
+
+// Aligns the amount of memory requested by the user with chunk size
+static inline size_t align(size_t size)
+{
+	const size_t alignment = 8;
+	size = (size + (alignment - 1)) & ~(alignment - 1);
+
+	if (size <= MIN)
+		return MIN;
+	else
+		return size;
+}
+
+struct gc_chunk *get_next_chunk(struct gc_chunk *curr)
+{
+	unsigned size = curr->size;
+	return (struct gc_chunk *)((uint64_t *)curr + MAGIC + (size - 1));
+}
+
+struct gc_chunk *get_prev_chunk(struct gc_chunk *curr)
+{
+	assert(curr->merge);
+	unsigned size = curr->footer;
+	return (struct gc_chunk *)((uint64_t *)curr - (size - 1) - MAGIC);
+}