+/* The current RDB version. When the format changes in a way that is no longer
+ * backward compatible this number gets incremented. */
+#define REDIS_RDB_VERSION 6
+
+/* Defines related to the dump file format. To store 32 bits lengths for short
+ * keys requires a lot of space, so we check the most significant 2 bits of
+ * the first byte to interpreter the length:
+ *
+ * 00|000000 => if the two MSB are 00 the len is the 6 bits of this byte
+ * 01|000000 00000000 => 01, the len is 14 byes, 6 bits + 8 bits of next byte
+ * 10|000000 [32 bit integer] => if it's 01, a full 32 bit len will follow
+ * 11|000000 this means: specially encoded object will follow. The six bits
+ * number specify the kind of object that follows.
+ * See the REDIS_RDB_ENC_* defines.
+ *
+ * Lenghts up to 63 are stored using a single byte, most DB keys, and may
+ * values, will fit inside. */
+#define REDIS_RDB_6BITLEN 0
+#define REDIS_RDB_14BITLEN 1
+#define REDIS_RDB_32BITLEN 2
+#define REDIS_RDB_ENCVAL 3
+#define REDIS_RDB_LENERR UINT_MAX
+
+/* When a length of a string object stored on disk has the first two bits
+ * set, the remaining two bits specify a special encoding for the object
+ * accordingly to the following defines: */
+#define REDIS_RDB_ENC_INT8 0 /* 8 bit signed integer */
+#define REDIS_RDB_ENC_INT16 1 /* 16 bit signed integer */
+#define REDIS_RDB_ENC_INT32 2 /* 32 bit signed integer */
+#define REDIS_RDB_ENC_LZF 3 /* string compressed with FASTLZ */
+
+/* Dup object types to RDB object types. Only reason is readability (are we
+ * dealing with RDB types or with in-memory object types?). */
+#define REDIS_RDB_TYPE_STRING 0
+#define REDIS_RDB_TYPE_LIST 1
+#define REDIS_RDB_TYPE_SET 2
+#define REDIS_RDB_TYPE_ZSET 3
+#define REDIS_RDB_TYPE_HASH 4
+
+/* Object types for encoded objects. */
+#define REDIS_RDB_TYPE_HASH_ZIPMAP 9
+#define REDIS_RDB_TYPE_LIST_ZIPLIST 10
+#define REDIS_RDB_TYPE_SET_INTSET 11
+#define REDIS_RDB_TYPE_ZSET_ZIPLIST 12
+#define REDIS_RDB_TYPE_HASH_ZIPLIST 13
+
+/* Test if a type is an object type. */
+#define rdbIsObjectType(t) ((t >= 0 && t <= 4) || (t >= 9 && t <= 12))
+
+/* Special RDB opcodes (saved/loaded with rdbSaveType/rdbLoadType). */
+#define REDIS_RDB_OPCODE_EXPIRETIME_MS 252
+#define REDIS_RDB_OPCODE_EXPIRETIME 253
+#define REDIS_RDB_OPCODE_SELECTDB 254
+#define REDIS_RDB_OPCODE_EOF 255
+
+/* Test if a type is an opcode. */
+#define rdbIsOpcode(t) (t >= 253 && t <= 255)
+
+int rdbSaveType(rio *rdb, unsigned char type);
+int rdbLoadType(rio *rdb);
+int rdbSaveTime(rio *rdb, time_t t);
+time_t rdbLoadTime(rio *rdb);
+int rdbSaveLen(rio *rdb, uint32_t len);
+uint32_t rdbLoadLen(rio *rdb, int *isencoded);
+int rdbSaveObjectType(rio *rdb, robj *o);
+int rdbLoadObjectType(rio *rdb);