root/btree/src/btree.h

/* 
 * ADT of Btree
 */

#define BLOCK_SIZE      4096
#define KEY_SIZE        160
#define ENTRY_SIZE      (KEY_SIZE+8)
#define ENTRY_PER_NODE  ((BLOCK_SIZE-16)/ENTRY_SIZE) 

/* sizeof(btree_entry) == NODE_SIZE */
typedef struct {
        char    key[KEY_SIZE];  /* key */
        int     value;          /* var */
        int     child;          /* offset of next child */
} btree_entry;

/* sizeof(btree_node) < BLOCK_SIZE */
typedef struct {
        int     n;              /* number of entries */
        int     prev_node;      /* offset of previous node */
        int     next_node;      /* offset of next node */
        int     child;          /* offset of first child  */
        btree_entry entry[ENTRY_PER_NODE];
} btree_node;

typedef struct {
        int     fd;     /* btree file pointer */
        int     root;   /* offset of root node */
        int     depth;  /* depth of tree */
        int (*compare)( btree_entry* l, btree_entry* r );
} btree;

//btree* btree_open( char* btree_file );
void btree_insert( btree* tree, char* key );