assert( memIsValid(pArg) );
    apVal[i] = pArg;
    Deephemeralize(pArg);
    sqlite3VdbeMemStoreType(pArg);
    REGISTER_TRACE(pOp->p2+i, pArg);
  }

  assert( pOp->p4type==P4_FUNCDEF );

  ctx.pFunc = pOp->p4.pFunc;






  ctx.s.flags = MEM_Null;
  ctx.s.db = db;
  ctx.s.xDel = 0;
  ctx.s.zMalloc = 0;
  ctx.iOp = pc;
  ctx.pVdbe = p;

  /* The output cell may already have a buffer allocated. Move
  ** the pointer to ctx.s so in case the user-function can use
  ** the already allocated buffer instead of allocating a new one.
  */
  sqlite3VdbeMemMove(&ctx.s, pOut);
  MemSetTypeFlag(&ctx.s, MEM_Null);

  db->lastRowid = lastRowid;
  (*ctx.pFunc->xFunc)(&ctx, n, apVal); /* IMP: R-24505-23230 */
  lastRowid = db->lastRowid;

  /* If any auxiliary data functions have been called by this user function,
  ** immediately call the destructor for any non-static values.
  */

  sqlite3VdbeDeleteAuxData(p, pc, pOp->p1);




  if( db->mallocFailed ){
    /* Even though a malloc() has failed, the implementation of the
    ** user function may have called an sqlite3_result_XXX() function
    ** to return a value. The following call releases any resources
    ** associated with such a value.
    */

*/
typedef struct Vdbe Vdbe;

/*
** The names of the following types declared in vdbeInt.h are required
** for the VdbeOp definition.
*/

typedef struct Mem Mem;
typedef struct SubProgram SubProgram;

/*
** A single instruction of the virtual machine has an opcode
** and as many as three operands.  The instruction is recorded
** as an instance of the following structure:

  union {             /* fourth parameter */
    int i;                 /* Integer value if p4type==P4_INT32 */
    void *p;               /* Generic pointer */
    char *z;               /* Pointer to data for string (char array) types */
    i64 *pI64;             /* Used when p4type is P4_INT64 */
    double *pReal;         /* Used when p4type is P4_REAL */
    FuncDef *pFunc;        /* Used when p4type is P4_FUNCDEF */

    CollSeq *pColl;        /* Used when p4type is P4_COLLSEQ */
    Mem *pMem;             /* Used when p4type is P4_MEM */
    VTable *pVtab;         /* Used when p4type is P4_VTAB */
    KeyInfo *pKeyInfo;     /* Used when p4type is P4_KEYINFO */
    int *ai;               /* Used when p4type is P4_INTARRAY */
    SubProgram *pProgram;  /* Used when p4type is P4_SUBPROGRAM */
    int (*xAdvance)(BtCursor *, int *);

*/
#define P4_NOTUSED    0   /* The P4 parameter is not used */
#define P4_DYNAMIC  (-1)  /* Pointer to a string obtained from sqliteMalloc() */
#define P4_STATIC   (-2)  /* Pointer to a static string */
#define P4_COLLSEQ  (-4)  /* P4 is a pointer to a CollSeq structure */
#define P4_FUNCDEF  (-5)  /* P4 is a pointer to a FuncDef structure */
#define P4_KEYINFO  (-6)  /* P4 is a pointer to a KeyInfo structure */

#define P4_MEM      (-8)  /* P4 is a pointer to a Mem*    structure */
#define P4_TRANSIENT  0   /* P4 is a pointer to a transient string */
#define P4_VTAB     (-10) /* P4 is a pointer to an sqlite3_vtab structure */
#define P4_MPRINTF  (-11) /* P4 is a string obtained from sqlite3_mprintf() */
#define P4_REAL     (-12) /* P4 is a 64-bit floating point value */
#define P4_INT64    (-13) /* P4 is a 64-bit signed integer */
#define P4_INT32    (-14) /* P4 is a 32-bit signed integer */

/* Opaque type used by code in vdbesort.c */
typedef struct VdbeSorter VdbeSorter;

/* Opaque type used by the explainer */
typedef struct Explain Explain;

/* Elements of the linked list at Vdbe.pAuxData */
typedef struct AuxData AuxData;

/*
** A cursor is a pointer into a single BTree within a database file.
** The cursor can seek to a BTree entry with a particular key, or
** loop over all entries of the Btree.  You can also insert new BTree
** entries or retrieve the key or data from the entry that the cursor
** is currently pointing to.
** 

** Return true if a memory cell is not marked as invalid.  This macro
** is for use inside assert() statements only.
*/
#ifdef SQLITE_DEBUG
#define memIsValid(M)  ((M)->flags & MEM_Invalid)==0
#endif

/*
** Each auxilliary data pointer stored by a user defined function 


** implementation calling sqlite3_set_auxdata() is stored in an instance
** of this structure. All such structures associated with a single VM


** are stored in a linked list headed at Vdbe.pAuxData. All are destroyed
** when the VM is halted (if not before).
*/



struct AuxData {
  int iOp;                        /* Instruction number of OP_Function opcode */
  int iArg;                       /* Index of function argument. */
  void *pAux;                     /* Aux data pointer */
  void (*xDelete)(void *);        /* Destructor for the aux data */
  AuxData *pNext;                 /* Next element in list */
};

/*
** The "context" argument for a installable function.  A pointer to an
** instance of this structure is the first argument to the routines used
** implement the SQL functions.
**
** There is a typedef for this structure in sqlite.h.  So all routines,
** even the public interface to SQLite, can use a pointer to this structure.
** But this file is the only place where the internal details of this
** structure are known.
**
** This structure is defined inside of vdbeInt.h because it uses substructures
** (Mem) which are only defined there.
*/
struct sqlite3_context {
  FuncDef *pFunc;       /* Pointer to function information.  MUST BE FIRST */

  Mem s;                /* The return value is stored here */
  Mem *pMem;            /* Memory cell used to store aggregate context */
  CollSeq *pColl;       /* Collating sequence */
  int isError;          /* Error code returned by the function. */
  int skipFlag;         /* Skip skip accumulator loading if true */
  int iOp;              /* Instruction number of OP_Function */
  Vdbe *pVdbe;          /* The VM that owns this context */
};

/*
** An Explain object accumulates indented output which is helpful
** in describing recursive data structures.
*/
struct Explain {

  VdbeFrame *pFrame;      /* Parent frame */
  VdbeFrame *pDelFrame;   /* List of frame objects to free on VM reset */
  int nFrame;             /* Number of frames in pFrame list */
  u32 expmask;            /* Binding to these vars invalidates VM */
  SubProgram *pProgram;   /* Linked list of all sub-programs used by VM */
  int nOnceFlag;          /* Size of array aOnceFlag[] */
  u8 *aOnceFlag;          /* Flags for OP_Once */
  AuxData *pAuxData;      /* Linked list of auxdata allocations */
};

/*
** The following are allowed values for Vdbe.magic
*/
#define VDBE_MAGIC_INIT     0x26bceaa5    /* Building a VDBE program */
#define VDBE_MAGIC_RUN      0xbdf20da3    /* VDBE is ready to execute */

#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
void sqlite3VdbePrintOp(FILE*, int, Op*);
#endif
u32 sqlite3VdbeSerialTypeLen(u32);
u32 sqlite3VdbeSerialType(Mem*, int);
u32 sqlite3VdbeSerialPut(unsigned char*, int, Mem*, int);
u32 sqlite3VdbeSerialGet(const unsigned char*, u32, Mem*);
void sqlite3VdbeDeleteAuxData(Vdbe*, int, int);

int sqlite2BtreeKeyCompare(BtCursor *, const void *, int, int, int *);
int sqlite3VdbeIdxKeyCompare(VdbeCursor*,UnpackedRecord*,int*);
int sqlite3VdbeIdxRowid(sqlite3*, BtCursor *, i64 *);
int sqlite3MemCompare(const Mem*, const Mem*, const CollSeq*);
int sqlite3VdbeExec(Vdbe*);
int sqlite3VdbeList(Vdbe*);

}

/*
** Return the auxilary data pointer, if any, for the iArg'th argument to
** the user-function defined by pCtx.
*/
void *sqlite3_get_auxdata(sqlite3_context *pCtx, int iArg){
  AuxData *pAuxData;

  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );
  for(pAuxData=pCtx->pVdbe->pAuxData; pAuxData; pAuxData=pAuxData->pNext){
    if( pAuxData->iOp==pCtx->iOp && pAuxData->iArg==iArg ) break;

  }

  return (pAuxData ? pAuxData->pAux : 0);
}

/*
** Set the auxilary data pointer and delete function, for the iArg'th
** argument to the user-function defined by pCtx. Any previous value is
** deleted by calling the delete function specified when it was set.
*/
void sqlite3_set_auxdata(
  sqlite3_context *pCtx, 
  int iArg, 
  void *pAux, 
  void (*xDelete)(void*)
){
  AuxData *pAuxData;
  Vdbe *pVdbe = pCtx->pVdbe;


  assert( sqlite3_mutex_held(pCtx->s.db->mutex) );






  if( iArg<0 ) goto failed;



  for(pAuxData=pVdbe->pAuxData; pAuxData; pAuxData=pAuxData->pNext){
    if( pAuxData->iOp==pCtx->iOp && pAuxData->iArg==iArg ) break;
  }
  if( pAuxData==0 ){
    pAuxData = sqlite3DbMallocZero(pVdbe->db, sizeof(AuxData));
    if( !pAuxData ) goto failed;
    pAuxData->iOp = pCtx->iOp;
    pAuxData->iArg = iArg;
    pAuxData->pNext = pVdbe->pAuxData;
    pVdbe->pAuxData = pAuxData;
  }else if( pAuxData->xDelete ){
    pAuxData->xDelete(pAuxData->pAux);
  }

  pAuxData->pAux = pAux;
  pAuxData->xDelete = xDelete;
  return;

failed:
  if( xDelete ){
    xDelete(pAux);

        sqlite3DbFree(db, p4);
        break;
      }
      case P4_MPRINTF: {
        if( db->pnBytesFreed==0 ) sqlite3_free(p4);
        break;
      }







      case P4_FUNCDEF: {
        freeEphemeralFunction(db, (FuncDef*)p4);
        break;
      }
      case P4_MEM: {
        if( db->pnBytesFreed==0 ){
          sqlite3ValueFree((sqlite3_value*)p4);

    releaseMemArray(&p->aMem[1], p->nMem);
  }
  while( p->pDelFrame ){
    VdbeFrame *pDel = p->pDelFrame;
    p->pDelFrame = pDel->pParent;
    sqlite3VdbeFrameDelete(pDel);
  }

  /* Delete any auxdata allocations made by the VM */
  sqlite3VdbeDeleteAuxData(p, -1, 0);
  assert( p->pAuxData==0 );
}

/*
** Clean up the VM after execution.
**
** This routine will automatically close any cursors, lists, and/or
** sorters that were left open.  It also deletes the values of

    assert( (rc & p->db->errMask)==rc );
  }
  sqlite3VdbeDelete(p);
  return rc;
}

/*
** If parameter iOp is less than zero, then invoke the destructor for
** all auxiliary data pointers currently cached by the VM passed as
** the first argument.
**
** Or, if iOp is greater than or equal to zero, then the destructor is
** only invoked for those auxiliary data pointers created by the user 
** function invoked by the OP_Function opcode at instruction iOp of 
** VM pVdbe, and only then if:
**
**    * the associated function parameter is the 32nd or later (counting
**      from left to right), or
**
**    * the corresponding bit in argument mask is clear (where the first


**      function parameter corrsponds to bit 0 etc.).
*/
void sqlite3VdbeDeleteAuxData(Vdbe *pVdbe, int iOp, int mask){

  AuxData **pp = &pVdbe->pAuxData;
  while( *pp ){
    AuxData *pAux = *pp;
    if( (iOp<0)
     || (pAux->iOp==iOp && (pAux->iArg>31 || !(mask & ((u32)1<<pAux->iArg))))
    ){
      if( pAux->xDelete ){
        pAux->xDelete(pAux->pAux);
      }
      *pp = pAux->pNext;
      sqlite3DbFree(pVdbe->db, pAux);
    }else{
      pp= &pAux->pNext;
    }
  }
}

/*
** Free all memory associated with the Vdbe passed as the second argument,
** except for object itself, which is preserved.

  sqlite3_bind_text $STMT 1 hello\000 -1
  set res [list]
  while { "SQLITE_ROW"==[sqlite3_step $STMT] } {
    lappend res [sqlite3_column_text $STMT 0]
  }
  lappend res [sqlite3_finalize $STMT]
} {{0 0} {1 0} SQLITE_OK}

# Test that auxiliary data is discarded when a statement is reset.
do_execsql_test 13.8.1 {
  SELECT test_auxdata('constant') FROM t4;
} {0 1}
do_execsql_test 13.8.2 {
  SELECT test_auxdata('constant') FROM t4;
} {0 1}
db cache flush
do_execsql_test 13.8.3 {
  SELECT test_auxdata('constant') FROM t4;
} {0 1}
set V "one"
do_execsql_test 13.8.4 {
  SELECT test_auxdata($V), $V FROM t4;
} {0 one 1 one}
set V "two"
do_execsql_test 13.8.5 {
  SELECT test_auxdata($V), $V FROM t4;
} {0 two 1 two}
db cache flush
set V "three"
do_execsql_test 2.3 {
  SELECT test_auxdata($V), $V FROM t4;
} {0 three 1 three}


# Make sure that a function with a very long name is rejected
do_test func-14.1 {
  catch {
    db function [string repeat X 254] {return "hello"}
  } 
} {0}