**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.860 2009/06/22 12:05:10 drh Exp $
*/
#include "sqliteInt.h"
#include "vdbeInt.h"

/*
** The following global variable is incremented every time a cursor
** moves, either by the OP_SeekXX, OP_Next, or OP_Prev opcodes.  The test
................................................................................
      ** larger than 32 bits. */
      assert( (payloadSize64 & SQLITE_MAX_U32)==(u64)payloadSize64 );
      payloadSize = (u32)payloadSize64;
    }else{
      sqlite3BtreeDataSize(pCrsr, &payloadSize);
    }
    nField = pC->nField;
  }else{
    assert( pC->pseudoTable );
    /* The record is the sole entry of a pseudo-table */
    payloadSize = pC->nData;
    zRec = pC->pData;
    pC->cacheStatus = CACHE_STALE;
    assert( payloadSize==0 || zRec!=0 );
    nField = pC->nField;
    pCrsr = 0;



  }

  /* If payloadSize is 0, then just store a NULL */
  if( payloadSize==0 ){
    assert( pDest->flags&MEM_Null );
    goto op_column_out;
  }
................................................................................
  }
  if( pOp->p5 ){
    assert( p2>0 );
    assert( p2<=p->nMem );
    pIn2 = &p->aMem[p2];
    sqlite3VdbeMemIntegerify(pIn2);
    p2 = (int)pIn2->u.i;




    if( NEVER(p2<2) ) {
      rc = SQLITE_CORRUPT_BKPT;
      goto abort_due_to_error;
    }
  }
  if( pOp->p4type==P4_KEYINFO ){
    pKeyInfo = pOp->p4.pKeyInfo;
................................................................................
  */
  if( db->xUpdateCallback && pOp->p4.z ){
    assert( pC->isTable );
    assert( pC->rowidIsValid );  /* lastRowid set by previous OP_NotFound */
    iKey = pC->lastRowid;
  }









  rc = sqlite3VdbeCursorMoveto(pC);
  if( rc ) goto abort_due_to_error;

  sqlite3BtreeSetCachedRowid(pC->pCursor, 0);
  rc = sqlite3BtreeDelete(pC->pCursor);
  pC->cacheStatus = CACHE_STALE;

  /* Invoke the update-hook if required. */
  if( rc==SQLITE_OK && db->xUpdateCallback && pOp->p4.z ){
    const char *zDb = db->aDb[pC->iDb].zName;
................................................................................
  assert( pC->isTable || pOp->opcode==OP_RowKey );
  assert( pC->isIndex || pOp->opcode==OP_RowData );
  assert( pC!=0 );
  assert( pC->nullRow==0 );
  assert( pC->pseudoTable==0 );
  assert( pC->pCursor!=0 );
  pCrsr = pC->pCursor;







  rc = sqlite3VdbeCursorMoveto(pC);
  if( rc ) goto abort_due_to_error;

  if( pC->isIndex ){
    assert( !pC->isTable );
    sqlite3BtreeKeySize(pCrsr, &n64);
    if( n64>db->aLimit[SQLITE_LIMIT_LENGTH] ){
      goto too_big;
    }
    n = (u32)n64;
................................................................................
  BtCursor *pCrsr;
  int res;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  pCrsr = pC->pCursor;
  assert( pCrsr!=0 );


  rc = sqlite3BtreeLast(pCrsr, &res);

  pC->nullRow = (u8)res;
  pC->deferredMoveto = 0;
  pC->rowidIsValid = 0;
  pC->cacheStatus = CACHE_STALE;
  if( res && pOp->p2>0 ){
    pc = pOp->p2 - 1;
  }
  break;
}


/* Opcode: Sort P1 P2 * * *
................................................................................
  CHECK_FOR_INTERRUPT;
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  if( pC==0 ){
    break;  /* See ticket #2273 */
  }
  pCrsr = pC->pCursor;
  assert( pCrsr );



  res = 1;
  assert( pC->deferredMoveto==0 );
  rc = pOp->opcode==OP_Next ? sqlite3BtreeNext(pCrsr, &res) :
                              sqlite3BtreePrevious(pCrsr, &res);
  pC->nullRow = (u8)res;
  pC->cacheStatus = CACHE_STALE;
  if( res==0 ){
................................................................................
  const char *zKey;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pIn2->flags & MEM_Blob );
  pCrsr = pC->pCursor;
  if( pCrsr!=0 ){
    assert( pC->isTable==0 );
    rc = ExpandBlob(pIn2);
    if( rc==SQLITE_OK ){
      nKey = pIn2->n;
      zKey = pIn2->z;
      rc = sqlite3BtreeInsert(pCrsr, zKey, nKey, "", 0, 0, pOp->p3, 
          ((pOp->p5 & OPFLAG_USESEEKRESULT) ? pC->seekResult : 0)
................................................................................
** The content of P3 registers starting at register P2 form
** an unpacked index key. This opcode removes that entry from the 
** index opened by cursor P1.
*/
case OP_IdxDelete: {
  VdbeCursor *pC;
  BtCursor *pCrsr;



  assert( pOp->p3>0 );
  assert( pOp->p2>0 && pOp->p2+pOp->p3<=p->nMem+1 );
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  pCrsr = pC->pCursor;
  if( pCrsr!=0 ){
    int res;
    UnpackedRecord r;
    r.pKeyInfo = pC->pKeyInfo;
    r.nField = (u16)pOp->p3;
    r.flags = 0;
    r.aMem = &p->aMem[pOp->p2];
    rc = sqlite3BtreeMovetoUnpacked(pCrsr, &r, 0, 0, &res);
    if( rc==SQLITE_OK && res==0 ){
      rc = sqlite3BtreeDelete(pCrsr);
................................................................................
  VdbeCursor *pC;
  i64 rowid;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  pCrsr = pC->pCursor;
  if( pCrsr!=0 ){
    rc = sqlite3VdbeCursorMoveto(pC);
    if( rc ) goto abort_due_to_error;
    assert( pC->deferredMoveto==0 );
    assert( pC->isTable==0 );
    if( !pC->nullRow ){
      rc = sqlite3VdbeIdxRowid(pCrsr, &rowid);
      if( rc!=SQLITE_OK ){
        goto abort_due_to_error;
      }
................................................................................
  VdbeCursor *pC;
  int res;
  UnpackedRecord r;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  if( pC->pCursor!=0 ){
    assert( pC->deferredMoveto==0 );
    assert( pOp->p5==0 || pOp->p5==1 );
    assert( pOp->p4type==P4_INT32 );
    r.pKeyInfo = pC->pKeyInfo;
    r.nField = (u16)pOp->p4.i;
    if( pOp->p5 ){
      r.flags = UNPACKED_INCRKEY | UNPACKED_IGNORE_ROWID;
................................................................................
  ** schema of database iDb before the SQL statement runs. The schema
  ** will not be reloaded becuase the db->init.busy flag is set. This
  ** can result in a "no such table: sqlite_master" or "malformed
  ** database schema" error being returned to the user.
  */
  assert( sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) );
  sqlite3BtreeEnterAll(db);
  if( pOp->p2 || DbHasProperty(db, iDb, DB_SchemaLoaded) ){
    zMaster = SCHEMA_TABLE(iDb);
    initData.db = db;
    initData.iDb = pOp->p1;
    initData.pzErrMsg = &p->zErrMsg;
    zSql = sqlite3MPrintf(db,
       "SELECT name, rootpage, sql FROM '%q'.%s WHERE %s",
       db->aDb[iDb].zName, zMaster, pOp->p4.z);

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.861 2009/06/22 19:05:41 drh Exp $
*/
#include "sqliteInt.h"
#include "vdbeInt.h"

/*
** The following global variable is incremented every time a cursor
** moves, either by the OP_SeekXX, OP_Next, or OP_Prev opcodes.  The test
................................................................................
      ** larger than 32 bits. */
      assert( (payloadSize64 & SQLITE_MAX_U32)==(u64)payloadSize64 );
      payloadSize = (u32)payloadSize64;
    }else{
      sqlite3BtreeDataSize(pCrsr, &payloadSize);
    }
    nField = pC->nField;

  }else if( pC->pseudoTable ){
    /* The record is the sole entry of a pseudo-table */
    payloadSize = pC->nData;
    zRec = pC->pData;
    pC->cacheStatus = CACHE_STALE;
    assert( payloadSize==0 || zRec!=0 );
    nField = pC->nField;
    pCrsr = 0;
  }else{
    /* Consider the row to be NULL */
    payloadSize = 0;
  }

  /* If payloadSize is 0, then just store a NULL */
  if( payloadSize==0 ){
    assert( pDest->flags&MEM_Null );
    goto op_column_out;
  }
................................................................................
  }
  if( pOp->p5 ){
    assert( p2>0 );
    assert( p2<=p->nMem );
    pIn2 = &p->aMem[p2];
    sqlite3VdbeMemIntegerify(pIn2);
    p2 = (int)pIn2->u.i;
    /* The p2 value always comes from a prior OP_CreateTable opcode and
    ** that opcode will always set the p2 value to 2 or more or else fail.
    ** If there were a failure, the prepared statement would have halted
    ** before reaching this instruction. */
    if( NEVER(p2<2) ) {
      rc = SQLITE_CORRUPT_BKPT;
      goto abort_due_to_error;
    }
  }
  if( pOp->p4type==P4_KEYINFO ){
    pKeyInfo = pOp->p4.pKeyInfo;
................................................................................
  */
  if( db->xUpdateCallback && pOp->p4.z ){
    assert( pC->isTable );
    assert( pC->rowidIsValid );  /* lastRowid set by previous OP_NotFound */
    iKey = pC->lastRowid;
  }

  /* The OP_Delete opcode always follows an OP_NotExists or OP_Last or
  ** OP_Column on the same table without any intervening operations that
  ** might move or invalidate the cursor.  Hence cursor pC is always pointing
  ** to the row to be deleted and the sqlite3VdbeCursorMoveto() operation
  ** below is always a no-op and cannot fail.  We will run it anyhow, though,
  ** to guard against future changes to the code generator.
  **/
  assert( pC->deferredMoveto==0 );
  rc = sqlite3VdbeCursorMoveto(pC);
  if( NEVER(rc!=SQLITE_OK) ) goto abort_due_to_error;

  sqlite3BtreeSetCachedRowid(pC->pCursor, 0);
  rc = sqlite3BtreeDelete(pC->pCursor);
  pC->cacheStatus = CACHE_STALE;

  /* Invoke the update-hook if required. */
  if( rc==SQLITE_OK && db->xUpdateCallback && pOp->p4.z ){
    const char *zDb = db->aDb[pC->iDb].zName;
................................................................................
  assert( pC->isTable || pOp->opcode==OP_RowKey );
  assert( pC->isIndex || pOp->opcode==OP_RowData );
  assert( pC!=0 );
  assert( pC->nullRow==0 );
  assert( pC->pseudoTable==0 );
  assert( pC->pCursor!=0 );
  pCrsr = pC->pCursor;

  /* The OP_RowKey and OP_RowData opcodes always follow OP_NotExists or
  ** OP_Rewind/Op_Next with no intervening instructions that might invalidate
  ** the cursor.  Hence the following sqlite3VdbeCursorMoveto() call is always
  ** a no-op and can never fail.  But we leave it in place as a safety.
  */
  assert( pC->deferredMoveto==0 );
  rc = sqlite3VdbeCursorMoveto(pC);
  if( NEVER(rc!=SQLITE_OK) ) goto abort_due_to_error;

  if( pC->isIndex ){
    assert( !pC->isTable );
    sqlite3BtreeKeySize(pCrsr, &n64);
    if( n64>db->aLimit[SQLITE_LIMIT_LENGTH] ){
      goto too_big;
    }
    n = (u32)n64;
................................................................................
  BtCursor *pCrsr;
  int res;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  pCrsr = pC->pCursor;
  if( pCrsr==0 ){
    res = 1;
  }else{
    rc = sqlite3BtreeLast(pCrsr, &res);
  }
  pC->nullRow = (u8)res;
  pC->deferredMoveto = 0;
  pC->rowidIsValid = 0;
  pC->cacheStatus = CACHE_STALE;
  if( pOp->p2>0 && res ){
    pc = pOp->p2 - 1;
  }
  break;
}


/* Opcode: Sort P1 P2 * * *
................................................................................
  CHECK_FOR_INTERRUPT;
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  if( pC==0 ){
    break;  /* See ticket #2273 */
  }
  pCrsr = pC->pCursor;
  if( pCrsr==0 ){
    pC->nullRow = 1;
    break;
  }
  res = 1;
  assert( pC->deferredMoveto==0 );
  rc = pOp->opcode==OP_Next ? sqlite3BtreeNext(pCrsr, &res) :
                              sqlite3BtreePrevious(pCrsr, &res);
  pC->nullRow = (u8)res;
  pC->cacheStatus = CACHE_STALE;
  if( res==0 ){
................................................................................
  const char *zKey;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pIn2->flags & MEM_Blob );
  pCrsr = pC->pCursor;
  if( ALWAYS(pCrsr!=0) ){
    assert( pC->isTable==0 );
    rc = ExpandBlob(pIn2);
    if( rc==SQLITE_OK ){
      nKey = pIn2->n;
      zKey = pIn2->z;
      rc = sqlite3BtreeInsert(pCrsr, zKey, nKey, "", 0, 0, pOp->p3, 
          ((pOp->p5 & OPFLAG_USESEEKRESULT) ? pC->seekResult : 0)
................................................................................
** The content of P3 registers starting at register P2 form
** an unpacked index key. This opcode removes that entry from the 
** index opened by cursor P1.
*/
case OP_IdxDelete: {
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int res;
  UnpackedRecord r;

  assert( pOp->p3>0 );
  assert( pOp->p2>0 && pOp->p2+pOp->p3<=p->nMem+1 );
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  pCrsr = pC->pCursor;
  if( ALWAYS(pCrsr!=0) ){


    r.pKeyInfo = pC->pKeyInfo;
    r.nField = (u16)pOp->p3;
    r.flags = 0;
    r.aMem = &p->aMem[pOp->p2];
    rc = sqlite3BtreeMovetoUnpacked(pCrsr, &r, 0, 0, &res);
    if( rc==SQLITE_OK && res==0 ){
      rc = sqlite3BtreeDelete(pCrsr);
................................................................................
  VdbeCursor *pC;
  i64 rowid;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  pCrsr = pC->pCursor;
  if( ALWAYS(pCrsr!=0) ){
    rc = sqlite3VdbeCursorMoveto(pC);
    if( NEVER(rc) ) goto abort_due_to_error;
    assert( pC->deferredMoveto==0 );
    assert( pC->isTable==0 );
    if( !pC->nullRow ){
      rc = sqlite3VdbeIdxRowid(pCrsr, &rowid);
      if( rc!=SQLITE_OK ){
        goto abort_due_to_error;
      }
................................................................................
  VdbeCursor *pC;
  int res;
  UnpackedRecord r;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  if( ALWAYS(pC->pCursor!=0) ){
    assert( pC->deferredMoveto==0 );
    assert( pOp->p5==0 || pOp->p5==1 );
    assert( pOp->p4type==P4_INT32 );
    r.pKeyInfo = pC->pKeyInfo;
    r.nField = (u16)pOp->p4.i;
    if( pOp->p5 ){
      r.flags = UNPACKED_INCRKEY | UNPACKED_IGNORE_ROWID;
................................................................................
  ** schema of database iDb before the SQL statement runs. The schema
  ** will not be reloaded becuase the db->init.busy flag is set. This
  ** can result in a "no such table: sqlite_master" or "malformed
  ** database schema" error being returned to the user.
  */
  assert( sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) );
  sqlite3BtreeEnterAll(db);
  if( pOp->p2 || ALWAYS(DbHasProperty(db, iDb, DB_SchemaLoaded)) ){
    zMaster = SCHEMA_TABLE(iDb);
    initData.db = db;
    initData.iDb = pOp->p1;
    initData.pzErrMsg = &p->zErrMsg;
    zSql = sqlite3MPrintf(db,
       "SELECT name, rootpage, sql FROM '%q'.%s WHERE %s",
       db->aDb[iDb].zName, zMaster, pOp->p4.z);

**
*************************************************************************
** This file contains code used for creating, destroying, and populating
** a VDBE (or an "sqlite3_stmt" as it is known to the outside world.)  Prior
** to version 2.8.7, all this code was combined into the vdbe.c source file.
** But that file was getting too big so this subroutines were split out.
**
** $Id: vdbeaux.c,v 1.462 2009/06/22 00:55:31 drh Exp $
*/
#include "sqliteInt.h"
#include "vdbeInt.h"



/*
................................................................................
  p->magic = VDBE_MAGIC_DEAD;
  sqlite3DbFree(db, p->aOp);
  sqlite3DbFree(db, p->pFree);
  sqlite3DbFree(db, p);
}

/*




** If a MoveTo operation is pending on the given cursor, then do that
** MoveTo now.  Return an error code.  If no MoveTo is pending, this
** routine does nothing and returns SQLITE_OK.






*/
int sqlite3VdbeCursorMoveto(VdbeCursor *p){
  if( p->deferredMoveto ){
    int res, rc;
#ifdef SQLITE_TEST
    extern int sqlite3_search_count;
#endif

**
*************************************************************************
** This file contains code used for creating, destroying, and populating
** a VDBE (or an "sqlite3_stmt" as it is known to the outside world.)  Prior
** to version 2.8.7, all this code was combined into the vdbe.c source file.
** But that file was getting too big so this subroutines were split out.
**
** $Id: vdbeaux.c,v 1.463 2009/06/22 19:05:41 drh Exp $
*/
#include "sqliteInt.h"
#include "vdbeInt.h"



/*
................................................................................
  p->magic = VDBE_MAGIC_DEAD;
  sqlite3DbFree(db, p->aOp);
  sqlite3DbFree(db, p->pFree);
  sqlite3DbFree(db, p);
}

/*
** Make sure the cursor p is ready to read or write the row to which it
** was last positioned.  Return an error code if an OOM fault or I/O error
** prevents us from positioning the cursor to its correct position.
**
** If a MoveTo operation is pending on the given cursor, then do that


** MoveTo now.  If no move is pending, check to see if the row has been
** deleted out from under the cursor and if it has, mark the row as
** a NULL row.
**
** If the cursor is already pointing to the correct row and that row has
** not been deleted out from under the cursor, then this routine is a no-op.
*/
int sqlite3VdbeCursorMoveto(VdbeCursor *p){
  if( p->deferredMoveto ){
    int res, rc;
#ifdef SQLITE_TEST
    extern int sqlite3_search_count;
#endif

*************************************************************************
**
** This file contains code use to manipulate "Mem" structure.  A "Mem"
** stores a single value in the VDBE.  Mem is an opaque structure visible
** only within the VDBE.  Interface routines refer to a Mem using the
** name sqlite_value
**
** $Id: vdbemem.c,v 1.148 2009/06/17 16:20:04 drh Exp $
*/
#include "sqliteInt.h"
#include "vdbeInt.h"

/*
** Call sqlite3VdbeMemExpandBlob() on the supplied value (type Mem*)
** P if required.
................................................................................
** Change the value of a Mem to be a string or a BLOB.
**
** The memory management strategy depends on the value of the xDel
** parameter. If the value passed is SQLITE_TRANSIENT, then the 
** string is copied into a (possibly existing) buffer managed by the 
** Mem structure. Otherwise, any existing buffer is freed and the
** pointer copied.






*/
int sqlite3VdbeMemSetStr(
  Mem *pMem,          /* Memory cell to set to string value */
  const char *z,      /* String pointer */
  int n,              /* Bytes in string, or negative */
  u8 enc,             /* Encoding of z.  0 for BLOBs */
  void (*xDel)(void*) /* Destructor function */
................................................................................
    pMem->xDel = 0;
  }else{
    sqlite3VdbeMemRelease(pMem);
    pMem->z = (char *)z;
    pMem->xDel = xDel;
    flags |= ((xDel==SQLITE_STATIC)?MEM_Static:MEM_Dyn);
  }
  if( nByte>iLimit ){
    return SQLITE_TOOBIG;
  }

  pMem->n = nByte;
  pMem->flags = flags;
  pMem->enc = (enc==0 ? SQLITE_UTF8 : enc);
  pMem->type = (enc==0 ? SQLITE_BLOB : SQLITE_TEXT);

#ifndef SQLITE_OMIT_UTF16
  if( pMem->enc!=SQLITE_UTF8 && sqlite3VdbeMemHandleBom(pMem) ){
    return SQLITE_NOMEM;
  }
#endif





  return SQLITE_OK;
}

/*
** Compare the values contained by the two memory cells, returning
** negative, zero or positive if pMem1 is less than, equal to, or greater

*************************************************************************
**
** This file contains code use to manipulate "Mem" structure.  A "Mem"
** stores a single value in the VDBE.  Mem is an opaque structure visible
** only within the VDBE.  Interface routines refer to a Mem using the
** name sqlite_value
**
** $Id: vdbemem.c,v 1.149 2009/06/22 19:05:41 drh Exp $
*/
#include "sqliteInt.h"
#include "vdbeInt.h"

/*
** Call sqlite3VdbeMemExpandBlob() on the supplied value (type Mem*)
** P if required.
................................................................................
** Change the value of a Mem to be a string or a BLOB.
**
** The memory management strategy depends on the value of the xDel
** parameter. If the value passed is SQLITE_TRANSIENT, then the 
** string is copied into a (possibly existing) buffer managed by the 
** Mem structure. Otherwise, any existing buffer is freed and the
** pointer copied.
**
** If the string is too large (if it exceeds the SQLITE_LIMIT_LENGTH
** size limit) then no memory allocation occurs.  If the string can be
** stored without allocating memory, then it is.  If a memory allocation
** is required to store the string, then value of pMem is unchanged.  In
** either case, SQLITE_TOOBIG is returned.
*/
int sqlite3VdbeMemSetStr(
  Mem *pMem,          /* Memory cell to set to string value */
  const char *z,      /* String pointer */
  int n,              /* Bytes in string, or negative */
  u8 enc,             /* Encoding of z.  0 for BLOBs */
  void (*xDel)(void*) /* Destructor function */
................................................................................
    pMem->xDel = 0;
  }else{
    sqlite3VdbeMemRelease(pMem);
    pMem->z = (char *)z;
    pMem->xDel = xDel;
    flags |= ((xDel==SQLITE_STATIC)?MEM_Static:MEM_Dyn);
  }




  pMem->n = nByte;
  pMem->flags = flags;
  pMem->enc = (enc==0 ? SQLITE_UTF8 : enc);
  pMem->type = (enc==0 ? SQLITE_BLOB : SQLITE_TEXT);

#ifndef SQLITE_OMIT_UTF16
  if( pMem->enc!=SQLITE_UTF8 && sqlite3VdbeMemHandleBom(pMem) ){
    return SQLITE_NOMEM;
  }
#endif

  if( nByte>iLimit ){
    return SQLITE_TOOBIG;
  }

  return SQLITE_OK;
}

/*
** Compare the values contained by the two memory cells, returning
** negative, zero or positive if pMem1 is less than, equal to, or greater