SQLite

** is an instance of the following structure. 
*/
struct Mem {
  int i;              /* Integer value */
  int n;              /* Number of characters in string value, including '\0' */
  int flags;          /* Some combination of MEM_Null, MEM_Str, MEM_Dyn, etc. */
  double r;           /* Real value */
  char *z;            /* String or BLOB value */
  char zShort[NBFS];  /* Space for short strings */
};
typedef struct Mem Mem;

/*
** Allowed values for Mem.flags.
**
** The first 5 values determine the data type(s).  Null and Blob must
** occur alone.  But Str, Int, and Real can occur together.
**
** The next 3 utf entries determine the text representation for strings.
** These values are only meaningful if the type is Str.
**
** The last 4 values specify what kind of memory Mem.z points to.
** These valus are only meaningful if the Str or Blob types are used.
*/
#define MEM_Null      0x0001   /* Value is NULL */
#define MEM_Str       0x0002   /* Value is a string */
#define MEM_Int       0x0004   /* Value is an integer */
#define MEM_Real      0x0008   /* Value is a real number */
#define MEM_Blob      0x0010   /* Value is a BLOB */

#define MEM_Utf8      0x0020   /* String uses UTF-8 encoding */
#define MEM_Utf16be   0x0040   /* String uses UTF-16 big-endian */
#define MEM_Utf16le   0x0080   /* String uses UTF-16 little-endian */

#define MEM_Dyn       0x0100   /* Need to call sqliteFree() on Mem.z */
#define MEM_Static    0x0200   /* Mem.z points to a static string */
#define MEM_Ephem     0x0400   /* Mem.z points to an ephemeral string */
#define MEM_Short     0x0800   /* Mem.z points to Mem.zShort */

/* The following MEM_ value appears only in AggElem.aMem.s.flag fields.
** It indicates that the corresponding AggElem.aMem.z points to a
** aggregate function context that needs to be finalized.
*/
#define MEM_AggCtx    0x0100   /* Mem.z points to an agg function context */

void sqlite3VdbePrintOp(FILE*, int, Op*);
#endif
int sqlite3VdbeSerialize(const Mem *, unsigned char *);
int sqlite3VdbeSerialLen(const Mem *);
int sqlite3VdbeDeserialize(Mem *, const unsigned char *);

int sqlite2BtreeKeyCompare(BtCursor *, const void *, int, int, int *);