feat: update structure

cs2106/labs/lab4/bitmap/mymalloc.c

@@ -0,0 +1,40 @@
+#include "mymalloc.h"
+#include "bitmap.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+char _heap[MEMSIZE] = {0};
+unsigned char _bitmap[BITMAP_SIZE] = {};
+char lens[MEMSIZE] = {0};
+
+// Do not change this. Used by the test harness.
+// You may however use this function in your code if necessary.
+long get_index(void *ptr) {
+  if (ptr == NULL)
+    return -1;
+  else
+    return (long)((char *)ptr - &_heap[0]);
+}
+
+void print_memlist() { print_map(_bitmap, BITMAP_SIZE); }
+
+// Allocates size bytes of memory and returns a pointer
+// to the first byte.
+void *mymalloc(size_t size) {
+  long start = search_map(_bitmap, BITMAP_SIZE, size);
+  if (start == -1)
+    return NULL;
+  allocate_map(_bitmap, start, size);
+  lens[start] = size;
+  return (void *)(&_heap[start]);
+}
+
+// Frees memory pointer to by ptr.
+void myfree(void *ptr) {
+  if (ptr == NULL)
+    return;
+  long ptrIdx = get_index(ptr);
+  long size = lens[ptrIdx];
+  free_map(_bitmap, ptrIdx, size);
+  lens[ptrIdx] = 0;
+}