Initial

include/lalloc.h

@@ -0,0 +1,53 @@
+#ifndef LALLOC_H_
+#define LALLOC_H_
+
+#include <stdint.h>
+#include <stddef.h>
+
+#ifdef __ccplusplus
+extern "C" {
+#endif
+
+// Internal header added in front of each allocation
+typedef struct BlockHeader BlockHeader;
+struct BlockHeader {
+    uint32_t next;            // offset from base
+    uint32_t prev;            // offset from base
+    uint32_t size_and_flags;  // size | free_bit
+    // Padding to ensure we always return 16 byte aligned pointers.
+    uint8_t pad[4];
+};
+_Static_assert(sizeof(BlockHeader) == 16, "sizeof(BlockHeader) is not 16");
+
+/**
+ * General purpose allocator.
+ * - Allocated pointers are aligned to 16 bytes.
+ * - Backing buffer must be aligned to 16 bytes start
+ * - 4Gb - 16 is max for the allocator backing buffer.
+ * - Allocation of > 0 bytes returns a size aligned up to 16 bytes
+ * - Allocation of 0 bytes returns a valid pointer with 0 usable space
+ * The allocator maintains a doubly linked list of blocks,
+ * when blocks are free'd, adjacent blocks are merged to keep
+ * fragmentation to a minimum
+ */
+typedef struct LAlloc LAlloc;
+struct LAlloc {
+    uint8_t *base;            // backing store
+    uint32_t size;            // total size
+    BlockHeader *heap_start;  // first block
+    BlockHeader *next_alloc;  // start of free block search
+};
+
+void lalloc_init(LAlloc *allocator, void *backing_store, uint32_t size);
+
+void *lalloc(LAlloc *allocator, uint32_t size);
+void lfree(LAlloc *allocator, void *ptr);
+
+BlockHeader *block_from_offset(const LAlloc *allocator, uint32_t offset);
+uint32_t block_size(const BlockHeader *block);
+int block_is_free(const BlockHeader *block);
+
+#ifdef __ccplusplus
+}  // extern "C"
+#endif
+#endif