iterative api

buddy.h

@@ -1,24 +1,38 @@
 #include <stddef.h>
 #include <stdint.h>
 
-struct buddy_alloc {
-    void *base;
-    void *lists[5];
-    uint32_t *bitsets;
-    int num_bitsets;
+#define BUDDY_ALLOC_MAX_BLOCK_LOG2 12
+#define BUDDY_ALLOC_MIN_BLOCK_LOG2 8
+#define BUDDY_ALLOC_NUM_LISTS (BUDDY_ALLOC_MAX_BLOCK_LOG2 - BUDDY_ALLOC_MIN_BLOCK_LOG2 + 1)
+
+/*
+ * To keep track of the allocation state of a page,
+ * we need one bit for each possible block that can
+ * be made out of it. For instance, if the page can
+ * only be allocated in its entirety, 1 bit is required.
+ * If the blocks halfs can be allocated too, 3 bits
+ * are required: 1 for the page, 1 for the frist half
+ * and 1 for the second half. Allowing the allocation
+ * of page quarters requires 4 more bits, for a total
+ * of 7. In general, if we allow splitting a page N
+ * times (N=0 means only the entire page can be allocated),
+ * then 2^(N+1)-1 bits are necessary.
+ */
+#define BUDDY_ALLOC_BITS_PER_PAGE ((1U << (BUDDY_ALLOC_NUM_LISTS)) - 1)
+#define BUDDY_ALLOC_WORDS_PER_PAGE ((BUDDY_ALLOC_BITS_PER_PAGE + 31) / 32)
+
+struct page_info {
+    uint32_t bits[BUDDY_ALLOC_WORDS_PER_PAGE];
 };
 
-void init_buddy_alloc(struct buddy_alloc *alloc,
-                      char *base, size_t size,
-                      uint32_t *bitsets, int num_bitsets);
+struct buddy_alloc {
+    void *base;
+    void *lists[BUDDY_ALLOC_NUM_LISTS];
+    struct page_info *info;
+    int num_info;
+};
 
-void free_buddy_alloc(struct buddy_alloc *alloc);
-
-void *buddy_malloc(struct buddy_alloc *alloc,
-                   size_t len);
-
-void buddy_free(struct buddy_alloc *alloc,
-                void *ptr, size_t len);
-
-bool buddy_allocated(struct buddy_alloc *alloc,
-                     void *ptr, size_t len);
+struct buddy_alloc buddy_startup(char *base, size_t size, struct page_info *page_info, int num_page_info);
+void               buddy_cleanup(struct buddy_alloc *alloc);
+void              *buddy_malloc (struct buddy_alloc *alloc, size_t len);
+void               buddy_free   (struct buddy_alloc *alloc, size_t len, void *ptr);