SQLite

# all that automatic generation.
#
.target_source:	$(SRC)
	rm -rf tsrc
	mkdir -p tsrc
	cp $(SRC) tsrc
	rm tsrc/sqlite.h.in tsrc/parse.y
	$(TCLSH_CMD) $(TOP)/tool/vdbe-compress.tcl <tsrc/vdbe.c >vdbe.new
	mv vdbe.new tsrc/vdbe.c
	touch .target_source

sqlite3.c:	.target_source $(TOP)/tool/mksqlite3c.tcl
	$(TCLSH_CMD) $(TOP)/tool/mksqlite3c.tcl

# Rules to build the LEMON compiler generator
#

# This target creates a directory named "tsrc" and fills it with
# copies of all of the C source code and header files needed to
# build on the target system.  Some of the C source code and header
# files are automatically generated.  This target takes care of
# all that automatic generation.
#
target_source:	$(SRC) $(TOP)/tool/vdbe-compress.tcl
	rm -rf tsrc
	mkdir tsrc
	cp -f $(SRC) tsrc
	rm tsrc/sqlite.h.in tsrc/parse.y
	tclsh $(TOP)/tool/vdbe-compress.tcl <tsrc/vdbe.c >vdbe.new
	mv vdbe.new tsrc/vdbe.c
	touch target_source

sqlite3.c:	target_source $(TOP)/tool/mksqlite3c.tcl
	tclsh $(TOP)/tool/mksqlite3c.tcl
	cp sqlite3.c tclsqlite3.c
	cat $(TOP)/src/tclsqlite.c >>tclsqlite3.c

**
** 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 1.844 2009/06/02 15:21:42 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

#ifdef VDBE_PROFILE
  u64 start;                 /* CPU clock count at start of opcode */
  int origPc;                /* Program counter at start of opcode */
#endif
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  int nProgressOps = 0;      /* Opcodes executed since progress callback. */
#endif
  /*** INSERT STACK UNION HERE ***/



  assert( p->magic==VDBE_MAGIC_RUN );  /* sqlite3_step() verifies this */
  assert( db->magic==SQLITE_MAGIC_BUSY );
  sqlite3VdbeMutexArrayEnter(p);
  if( p->rc==SQLITE_NOMEM ){
    /* This happens if a malloc() inside a call to sqlite3_column_text() or
    ** sqlite3_column_text16() failed.  */

** Transfer the values of bound parameters P1..P1+P3-1 into registers
** P2..P2+P3-1.
**
** If the parameter is named, then its name appears in P4 and P3==1.
** The P4 value is used by sqlite3_bind_parameter_name().
*/
case OP_Variable: {
  int p1;          /* Variable to copy from */
  int p2;          /* Register to copy to */
  int n;           /* Number of values left to copy */
  Mem *pVar;       /* Value being transferred */

  p1 = pOp->p1 - 1;
  p2 = pOp->p2;

  n = pOp->p3;
  assert( p1>=0 && p1+n<=p->nVar );
  assert( p2>=1 && p2+n-1<=p->nMem );
  assert( pOp->p4.z==0 || pOp->p3==1 );

  while( n-- > 0 ){
    pVar = &p->aVar[p1++];
    if( sqlite3VdbeMemTooBig(pVar) ){
      goto too_big;
    }
    pOut = &p->aMem[p2++];
    sqlite3VdbeMemReleaseExternal(pOut);
    pOut->flags = MEM_Null;
    sqlite3VdbeMemShallowCopy(pOut, pVar, MEM_Static);
    UPDATE_MAX_BLOBSIZE(pOut);
  }
  break;
}

/* Opcode: Move P1 P2 P3 * *
**
** Move the values in register P1..P1+P3-1 over into
** registers P2..P2+P3-1.  Registers P1..P1+P1-1 are
** left holding a NULL.  It is an error for register ranges
** P1..P1+P3-1 and P2..P2+P3-1 to overlap.
*/
case OP_Move: {
  char *zMalloc;   /* Holding variable for allocated memory */
  int n;           /* Number of registers left to copy */
  int p1;          /* Register to copy from */
  int p2;          /* Register to copy to */

  n = pOp->p3;
  p1 = pOp->p1;
  p2 = pOp->p2;
  assert( n>0 && p1>0 && p2>0 );
  assert( p1+n<=p2 || p2+n<=p1 );

  pIn1 = &p->aMem[p1];
  pOut = &p->aMem[p2];
  while( n-- ){
    assert( pOut<=&p->aMem[p->nMem] );

** If either operand is NULL, the result is NULL.
*/
case OP_Add:                   /* same as TK_PLUS, in1, in2, out3 */
case OP_Subtract:              /* same as TK_MINUS, in1, in2, out3 */
case OP_Multiply:              /* same as TK_STAR, in1, in2, out3 */
case OP_Divide:                /* same as TK_SLASH, in1, in2, out3 */
case OP_Remainder: {           /* same as TK_REM, in1, in2, out3 */
  int flags;      /* Combined MEM_* flags from both inputs */
  i64 iA;         /* Integer value of left operand */
  i64 iB;         /* Integer value of right operand */
  double rA;      /* Real value of left operand */
  double rB;      /* Real value of right operand */

  applyNumericAffinity(pIn1);
  applyNumericAffinity(pIn2);
  flags = pIn1->flags | pIn2->flags;
  if( (flags & MEM_Null)!=0 ) goto arithmetic_result_is_null;
  if( (pIn1->flags & pIn2->flags & MEM_Int)==MEM_Int ){

    iA = pIn1->u.i;
    iB = pIn2->u.i;
    switch( pOp->opcode ){
      case OP_Add:         iB += iA;       break;
      case OP_Subtract:    iB -= iA;       break;
      case OP_Multiply:    iB *= iA;       break;
      case OP_Divide: {
        if( iA==0 ) goto arithmetic_result_is_null;
        /* Dividing the largest possible negative 64-bit integer (1<<63) by 
        ** -1 returns an integer too large to store in a 64-bit data-type. On
        ** some architectures, the value overflows to (1<<63). On others,
        ** a SIGFPE is issued. The following statement normalizes this
        ** behavior so that all architectures behave as if integer 
        ** overflow occurred.
        */
        if( iA==-1 && iB==SMALLEST_INT64 ) iA = 1;
        iB /= iA;
        break;
      }
      default: {
        if( iA==0 ) goto arithmetic_result_is_null;
        if( iA==-1 ) iA = 1;
        iB %= iA;
        break;
      }
    }
    pOut->u.i = iB;
    MemSetTypeFlag(pOut, MEM_Int);
  }else{

    rA = sqlite3VdbeRealValue(pIn1);
    rB = sqlite3VdbeRealValue(pIn2);
    switch( pOp->opcode ){
      case OP_Add:         rB += rA;       break;
      case OP_Subtract:    rB -= rA;       break;
      case OP_Multiply:    rB *= rA;       break;
      case OP_Divide: {
        /* (double)0 In case of SQLITE_OMIT_FLOATING_POINT... */
        if( rA==(double)0 ) goto arithmetic_result_is_null;
        rB /= rA;
        break;
      }
      default: {
        iA = rA;
        iB = rB;
        if( iA==0 ) goto arithmetic_result_is_null;
        if( iA==-1 ) iA = 1;
        rB = (double)(iB % iA);
        break;
      }
    }
    if( sqlite3IsNaN(rB) ){
      goto arithmetic_result_is_null;
    }
    pOut->r = rB;
    MemSetTypeFlag(pOut, MEM_Real);
    if( (flags & MEM_Real)==0 ){
      sqlite3VdbeIntegerAffinity(pOut);
    }
  }
  break;

** See also: AggStep and AggFinal
*/
case OP_Function: {
  int i;
  Mem *pArg;
  sqlite3_context ctx;
  sqlite3_value **apVal;
  int n;

  n = pOp->p5;
  apVal = p->apArg;
  assert( apVal || n==0 );

  assert( n==0 || (pOp->p2>0 && pOp->p2+n<=p->nMem+1) );
  assert( pOp->p3<pOp->p2 || pOp->p3>=pOp->p2+n );
  pArg = &p->aMem[pOp->p2];
  for(i=0; i<n; i++, pArg++){

** Store the result in register P3.
** If either input is NULL, the result is NULL.
*/
case OP_BitAnd:                 /* same as TK_BITAND, in1, in2, out3 */
case OP_BitOr:                  /* same as TK_BITOR, in1, in2, out3 */
case OP_ShiftLeft:              /* same as TK_LSHIFT, in1, in2, out3 */
case OP_ShiftRight: {           /* same as TK_RSHIFT, in1, in2, out3 */
  i64 a;
  i64 b;

  if( (pIn1->flags | pIn2->flags) & MEM_Null ){
    sqlite3VdbeMemSetNull(pOut);
    break;
  }
  a = sqlite3VdbeIntValue(pIn2);
  b = sqlite3VdbeIntValue(pIn1);

** only.  The KeyInfo elements are used sequentially.
**
** The comparison is a sort comparison, so NULLs compare equal,
** NULLs are less than numbers, numbers are less than strings,
** and strings are less than blobs.
*/
case OP_Compare: {
  int n;
  int i;
  int p1;
  int p2;
  const KeyInfo *pKeyInfo;
  int idx;
  CollSeq *pColl;    /* Collating sequence to use on this term */
  int bRev;          /* True for DESCENDING sort order */

  n = pOp->p3;
  pKeyInfo = pOp->p4.pKeyInfo;
  assert( n>0 );
  assert( pKeyInfo!=0 );
  p1 = pOp->p1;
  assert( p1>0 && p1+n<=p->nMem+1 );
  p2 = pOp->p2;
  assert( p2>0 && p2+n<=p->nMem+1 );
  for(i=0; i<n; i++){
    idx = aPermute ? aPermute[i] : i;


    REGISTER_TRACE(p1+idx, &p->aMem[p1+idx]);
    REGISTER_TRACE(p2+idx, &p->aMem[p2+idx]);
    assert( i<pKeyInfo->nField );
    pColl = pKeyInfo->aColl[i];
    bRev = pKeyInfo->aSortOrder[i];
    iCompare = sqlite3MemCompare(&p->aMem[p1+idx], &p->aMem[p2+idx], pColl);
    if( iCompare ){

**
** If either P1 or P2 is nonzero (true) then the result is 1 (true)
** even if the other input is NULL.  A NULL and false or two NULLs
** give a NULL output.
*/
case OP_And:              /* same as TK_AND, in1, in2, out3 */
case OP_Or: {             /* same as TK_OR, in1, in2, out3 */
  int v1;    /* Left operand:  0==FALSE, 1==TRUE, 2==UNKNOWN or NULL */
  int v2;    /* Right operand: 0==FALSE, 1==TRUE, 2==UNKNOWN or NULL */

  if( pIn1->flags & MEM_Null ){
    v1 = 2;
  }else{
    v1 = sqlite3VdbeIntValue(pIn1)!=0;
  }
  if( pIn2->flags & MEM_Null ){

**
** If the column contains fewer than P2 fields, then extract a NULL.  Or,
** if the P4 argument is a P4_MEM use the value of the P4 argument as
** the result.
*/
case OP_Column: {
  int payloadSize;   /* Number of bytes in the record */
  i64 payloadSize64; /* Number of bytes in the record */
  int p1;            /* P1 value of the opcode */
  int p2;            /* column number to retrieve */
  VdbeCursor *pC;    /* The VDBE cursor */
  char *zRec;        /* Pointer to complete record-data */
  BtCursor *pCrsr;   /* The BTree cursor */
  u32 *aType;        /* aType[i] holds the numeric type of the i-th column */
  u32 *aOffset;      /* aOffset[i] is offset to start of data for i-th column */
  int nField;        /* number of fields in the record */
  int len;           /* The length of the serialized data for the column */
  int i;             /* Loop counter */
  char *zData;       /* Part of the record being decoded */
  Mem *pDest;        /* Where to write the extracted value */
  Mem sMem;          /* For storing the record being decoded */
  u8 *zIdx;         /* Index into header */
  u8 *zEndHdr;      /* Pointer to first byte after the header */
  int offset;       /* Offset into the data */
  int szHdrSz;      /* Size of the header size field at start of record */
  int avail;        /* Number of bytes of available data */


  p1 = pOp->p1;
  p2 = pOp->p2;
  pC = 0;
  memset(&sMem, 0, sizeof(sMem));
  assert( p1<p->nCursor );
  assert( pOp->p3>0 && pOp->p3<=p->nMem );
  pDest = &p->aMem[pOp->p3];
  MemSetTypeFlag(pDest, MEM_Null);

  /* This block sets the variable payloadSize to be the total number of

    pCrsr = pC->pCursor;
    if( pC->nullRow ){
      payloadSize = 0;
    }else if( pC->cacheStatus==p->cacheCtr ){
      payloadSize = pC->payloadSize;
      zRec = (char*)pC->aRow;
    }else if( pC->isIndex ){

      sqlite3BtreeKeySize(pCrsr, &payloadSize64);
      payloadSize = (int)payloadSize64;
    }else{
      sqlite3BtreeDataSize(pCrsr, (u32 *)&payloadSize);
    }
    nField = pC->nField;
  }else{

  /* Read and parse the table header.  Store the results of the parse
  ** into the record header cache fields of the cursor.
  */
  aType = pC->aType;
  if( pC->cacheStatus==p->cacheCtr ){
    aOffset = pC->aOffset;
  }else{






    assert(aType);
    avail = 0;
    pC->aOffset = aOffset = &aType[nField];
    pC->payloadSize = payloadSize;
    pC->cacheStatus = p->cacheCtr;

    /* Figure out how many bytes are in the header */
    if( zRec ){
      zData = zRec;

    /* If we have read more header data than was contained in the header,
    ** or if the end of the last field appears to be past the end of the
    ** record, or if the end of the last field appears to be before the end
    ** of the record (when all fields present), then we must be dealing 
    ** with a corrupt database.
    */
    if( (zIdx > zEndHdr)|| (offset > payloadSize)
     || (zIdx==zEndHdr && offset!=payloadSize) ){
      rc = SQLITE_CORRUPT_BKPT;
      goto op_column_out;
    }
  }

  /* Get the column information. If aOffset[p2] is non-zero, then 

** Apply affinities to a range of P2 registers starting with P1.
**
** P4 is a string that is P2 characters long. The nth character of the
** string indicates the column affinity that should be used for the nth
** memory cell in the range.
*/
case OP_Affinity: {
  char *zAffinity;   /* The affinity to be applied */
  Mem *pData0;       /* First register to which to apply affinity */
  Mem *pLast;        /* Last register to which to apply affinity */
  Mem *pRec;         /* Current register */

  zAffinity = pOp->p4.z;
  pData0 = &p->aMem[pOp->p1];
  pLast = &pData0[pOp->p2-1];


  for(pRec=pData0; pRec<=pLast; pRec++){
    ExpandBlob(pRec);
    applyAffinity(pRec, zAffinity[pRec-pData0], encoding);
  }
  break;
}

**
** The mapping from character to affinity is given by the SQLITE_AFF_
** macros defined in sqliteInt.h.
**
** If P4 is NULL then all index fields have the affinity NONE.
*/
case OP_MakeRecord: {
  u8 *zNewRecord;        /* A buffer to hold the data for the new record */
  Mem *pRec;             /* The new record */
  u64 nData;             /* Number of bytes of data space */
  int nHdr;              /* Number of bytes of header space */
  i64 nByte;             /* Data space required for this record */
  int nZero;             /* Number of zero bytes at the end of the record */
  int nVarint;           /* Number of bytes in a varint */
  u32 serial_type;       /* Type field */
  Mem *pData0;           /* First field to be combined into the record */
  Mem *pLast;            /* Last field of the record */
  int nField;            /* Number of fields in the record */
  char *zAffinity;       /* The affinity string for the record */
  int file_format;       /* File format to use for encoding */
  int i;                 /* Space used in zNewRecord[] */
  int len;               /* Length of a field */

  /* Assuming the record contains N fields, the record format looks
  ** like this:
  **
  ** ------------------------------------------------------------------------
  ** | hdr-size | type 0 | type 1 | ... | type N-1 | data0 | ... | data N-1 | 
  ** ------------------------------------------------------------------------
  **
  ** Data(0) is taken from register P1.  Data(1) comes from register P1+1
  ** and so froth.
  **
  ** Each type field is a varint representing the serial type of the 
  ** corresponding data element (see sqlite3VdbeSerialType()). The
  ** hdr-size field is also a varint which is the offset from the beginning
  ** of the record to data0.
  */


  nData = 0;         /* Number of bytes of data space */
  nHdr = 0;          /* Number of bytes of header space */
  nByte = 0;         /* Data space required for this record */
  nZero = 0;         /* Number of zero bytes at the end of the record */









  nField = pOp->p1;
  zAffinity = pOp->p4.z;
  assert( nField>0 && pOp->p2>0 && pOp->p2+nField<=p->nMem+1 );
  pData0 = &p->aMem[nField];
  nField = pOp->p2;
  pLast = &pData0[nField-1];
  file_format = p->minWriteFileFormat;

  /* Loop through the elements that will make up the record to figure
  ** out how much space is required for the new record.
  */
  for(pRec=pData0; pRec<=pLast; pRec++){

    if( zAffinity ){
      applyAffinity(pRec, zAffinity[pRec-pData0], encoding);
    }
    if( pRec->flags&MEM_Zero && pRec->n>0 ){
      sqlite3VdbeMemExpandBlob(pRec);
    }
    serial_type = sqlite3VdbeSerialType(pRec, file_format);

** will be allocated and initialized.
**
** The statement is begun on the database file with index P1.  The main
** database file has an index of 0 and the file used for temporary tables
** has an index of 1.
*/
case OP_Statement: {
  int i;
  Btree *pBt;
  if( db->autoCommit==0 || db->activeVdbeCnt>1 ){
    i = pOp->p1;

    assert( i>=0 && i<db->nDb );
    assert( db->aDb[i].pBt!=0 );
    pBt = db->aDb[i].pBt;
    assert( sqlite3BtreeIsInTrans(pBt) );
    assert( (p->btreeMask & (1<<i))!=0 );
    if( p->iStatement==0 ){
      assert( db->nStatement>=0 && db->nSavepoint>=0 );

/* Opcode: Savepoint P1 * * P4 *
**
** Open, release or rollback the savepoint named by parameter P4, depending
** on the value of P1. To open a new savepoint, P1==0. To release (commit) an
** existing savepoint, P1==1, or to rollback an existing savepoint P1==2.
*/
case OP_Savepoint: {
  int p1;                         /* Value of P1 operand */
  char *zName;                    /* Name of savepoint */
  int nName;
  Savepoint *pNew;
  Savepoint *pSavepoint;
  Savepoint *pTmp;
  int iSavepoint;
  int ii;

  p1 = pOp->p1;
  zName = pOp->p4.z;

  /* Assert that the p1 parameter is valid. Also that if there is no open
  ** transaction, then there cannot be any savepoints. 
  */
  assert( db->pSavepoint==0 || db->autoCommit==0 );
  assert( p1==SAVEPOINT_BEGIN||p1==SAVEPOINT_RELEASE||p1==SAVEPOINT_ROLLBACK );
  assert( db->pSavepoint || db->isTransactionSavepoint==0 );
  assert( checkSavepointCount(db) );

  if( p1==SAVEPOINT_BEGIN ){
    if( db->writeVdbeCnt>0 ){
      /* A new savepoint cannot be created if there are active write 
      ** statements (i.e. open read/write incremental blob handles).
      */
      sqlite3SetString(&p->zErrMsg, db, "cannot open savepoint - "
        "SQL statements in progress");
      rc = SQLITE_BUSY;
    }else{
      nName = sqlite3Strlen30(zName);


      /* Create a new savepoint structure. */
      pNew = sqlite3DbMallocRaw(db, sizeof(Savepoint)+nName+1);
      if( pNew ){
        pNew->zName = (char *)&pNew[1];
        memcpy(pNew->zName, zName, nName+1);
    

    
        /* Link the new savepoint into the database handle's list. */
        pNew->pNext = db->pSavepoint;
        db->pSavepoint = pNew;
      }
    }
  }else{

    iSavepoint = 0;

    /* Find the named savepoint. If there is no such savepoint, then an
    ** an error is returned to the user.  */
    for(
      pSavepoint = db->pSavepoint; 
      pSavepoint && sqlite3StrICmp(pSavepoint->zName, zName);
      pSavepoint = pSavepoint->pNext
    ){
      iSavepoint++;
    }
    if( !pSavepoint ){
      sqlite3SetString(&p->zErrMsg, db, "no such savepoint: %s", zName);
      rc = SQLITE_ERROR;
    }else if( 

          db->autoCommit = 0;
          p->rc = rc = SQLITE_BUSY;
          goto vdbe_return;
        }
        db->isTransactionSavepoint = 0;
        rc = p->rc;
      }else{

        iSavepoint = db->nSavepoint - iSavepoint - 1;
        for(ii=0; ii<db->nDb; ii++){
          rc = sqlite3BtreeSavepoint(db->aDb[ii].pBt, p1, iSavepoint);
          if( rc!=SQLITE_OK ){
            goto abort_due_to_error;
          }
        }
        if( p1==SAVEPOINT_ROLLBACK && (db->flags&SQLITE_InternChanges)!=0 ){
          sqlite3ExpirePreparedStatements(db);
          sqlite3ResetInternalSchema(db, 0);
        }
      }
  
      /* Regardless of whether this is a RELEASE or ROLLBACK, destroy all 
      ** savepoints nested inside of the savepoint being operated on. */
      while( db->pSavepoint!=pSavepoint ){
        pTmp = db->pSavepoint;
        db->pSavepoint = pTmp->pNext;
        sqlite3DbFree(db, pTmp);
        db->nSavepoint--;
      }

      /* If it is a RELEASE, then destroy the savepoint being operated on too */
      if( p1==SAVEPOINT_RELEASE ){

** back any currently active btree transactions. If there are any active
** VMs (apart from this one), then a ROLLBACK fails.  A COMMIT fails if
** there are active writing VMs or active VMs that use shared cache.
**
** This instruction causes the VM to halt.
*/
case OP_AutoCommit: {
  int desiredAutoCommit;
  int rollback;
  int turnOnAC;

  desiredAutoCommit = pOp->p1;
  rollback = pOp->p2;
  turnOnAC = desiredAutoCommit && !db->autoCommit;
  assert( desiredAutoCommit==1 || desiredAutoCommit==0 );
  assert( desiredAutoCommit==1 || rollback==0 );

  assert( db->activeVdbeCnt>0 );  /* At least this one VM is active */

  if( turnOnAC && rollback && db->activeVdbeCnt>1 ){
    /* If this instruction implements a ROLLBACK and other VMs are
    ** still running, and a transaction is active, return an error indicating
    ** that the other VMs must complete first. 
    */

** write transaction must be started before any changes can be made to the
** database.  If P2 is 2 or greater then an EXCLUSIVE lock is also obtained
** on the file.
**
** If P2 is zero, then a read-lock is obtained on the database file.
*/
case OP_Transaction: {
  int i;
  Btree *pBt;

  i = pOp->p1;
  assert( i>=0 && i<db->nDb );
  assert( (p->btreeMask & (1<<i))!=0 );
  pBt = db->aDb[i].pBt;

  if( pBt ){
    rc = sqlite3BtreeBeginTrans(pBt, pOp->p2);
    if( rc==SQLITE_BUSY ){

**
** There must be a read-lock on the database (either a transaction
** must be started or there must be an open cursor) before
** executing this instruction.
*/
case OP_ReadCookie: {               /* out2-prerelease */
  int iMeta;
  int iDb;
  int iCookie;

  iDb = pOp->p1;
  iCookie = pOp->p3;
  assert( pOp->p3<SQLITE_N_BTREE_META );
  if( iDb<0 ){
    iDb = (-1*(iDb+1));
    iCookie *= -1;
  }
  assert( iDb>=0 && iDb<db->nDb );
  assert( db->aDb[iDb].pBt!=0 );

** in read/write mode.  For a given table, there can be one or more read-only
** cursors or a single read/write cursor but not both.
**
** See also OpenRead.
*/
case OP_OpenRead:
case OP_OpenWrite: {
  int nField;
  KeyInfo *pKeyInfo;
  int i;
  int p2;
  int iDb;
  int wrFlag;
  Btree *pX;
  VdbeCursor *pCur;
  Db *pDb;
  int flags;

  nField = 0;
  pKeyInfo = 0;
  i = pOp->p1;
  p2 = pOp->p2;
  iDb = pOp->p3;
  assert( iDb>=0 && iDb<db->nDb );
  assert( (p->btreeMask & (1<<iDb))!=0 );
  pDb = &db->aDb[iDb];
  pX = pDb->pBt;
  assert( pX!=0 );
  if( pOp->opcode==OP_OpenWrite ){
    wrFlag = 1;

  switch( rc ){
    case SQLITE_BUSY: {
      p->pc = pc;
      p->rc = rc = SQLITE_BUSY;
      goto vdbe_return;
    }
    case SQLITE_OK: {
      flags = sqlite3BtreeFlags(pCur->pCursor);
      /* Sanity checking.  Only the lower four bits of the flags byte should
      ** be used.  Bit 3 (mask 0x08) is unpredictable.  The lower 3 bits
      ** (mask 0x07) should be either 5 (intkey+leafdata for tables) or
      ** 2 (zerodata for indices).  If these conditions are not met it can
      ** only mean that we are dealing with a corrupt database file
      */
      if( (flags & 0xf0)!=0 || ((flags & 0x07)!=5 && (flags & 0x07)!=2) ){

** This opcode was once called OpenTemp.  But that created
** confusion because the term "temp table", might refer either
** to a TEMP table at the SQL level, or to a table opened by
** this opcode.  Then this opcode was call OpenVirtual.  But
** that created confusion with the whole virtual-table idea.
*/
case OP_OpenEphemeral: {
  int i;
  VdbeCursor *pCx;
  static const int openFlags = 
      SQLITE_OPEN_READWRITE |
      SQLITE_OPEN_CREATE |
      SQLITE_OPEN_EXCLUSIVE |
      SQLITE_OPEN_DELETEONCLOSE |
      SQLITE_OPEN_TRANSIENT_DB;

  i = pOp->p1;
  assert( i>=0 );
  pCx = allocateCursor(p, i, pOp->p2, -1, 1);
  if( pCx==0 ) goto no_mem;
  pCx->nullRow = 1;
  rc = sqlite3BtreeFactory(db, 0, 1, SQLITE_DEFAULT_TEMP_CACHE_SIZE, openFlags,
                           &pCx->pBt);
  if( rc==SQLITE_OK ){

** memory cell containing the row data is not overwritten until the
** pseudo table is closed (or a new row is inserted into it).
**
** P3 is the number of fields in the records that will be stored by
** the pseudo-table.
*/
case OP_OpenPseudo: {
  int i;
  VdbeCursor *pCx;

  i = pOp->p1;
  assert( i>=0 );
  pCx = allocateCursor(p, i, pOp->p3, -1, 0);
  if( pCx==0 ) goto no_mem;
  pCx->nullRow = 1;
  pCx->pseudoTable = 1;
  pCx->ephemPseudoTable = (u8)pOp->p2;
  pCx->isTable = 1;

**
** See also: Found, NotFound, Distinct, SeekGt, SeekGe, SeekLt
*/
case OP_SeekLt:         /* jump, in3 */
case OP_SeekLe:         /* jump, in3 */
case OP_SeekGe:         /* jump, in3 */
case OP_SeekGt: {       /* jump, in3 */
  int i;
  int res;
  int oc;
  VdbeCursor *pC;
  UnpackedRecord r;
  int nField;
  i64 iKey;      /* The rowid we are to seek to */

  i = pOp->p1;
  assert( i>=0 && i<p->nCursor );
  assert( pOp->p2!=0 );
  pC = p->apCsr[i];
  assert( pC!=0 );
  if( pC->pCursor!=0 ){

    oc = pOp->opcode;
    pC->nullRow = 0;
    if( pC->isTable ){


      /* The input value in P3 might be of any type: integer, real, string,
      ** blob, or NULL.  But it needs to be an integer before we can do
      ** the seek, so covert it. */
      applyNumericAffinity(pIn3);
      iKey = sqlite3VdbeIntValue(pIn3);
      pC->rowidIsValid = 0;

        goto abort_due_to_error;
      }
      if( res==0 ){
        pC->rowidIsValid = 1;
        pC->lastRowid = iKey;
      }
    }else{

      nField = pOp->p4.i;
      assert( pOp->p4type==P4_INT32 );
      assert( nField>0 );
      r.pKeyInfo = pC->pKeyInfo;
      r.nField = (u16)nField;
      if( oc==OP_SeekGt || oc==OP_SeekLe ){
        r.flags = UNPACKED_INCRKEY;
      }else{

** for P1 to move so that it points to the rowid given by P2.
**
** This is actually a deferred seek.  Nothing actually happens until
** the cursor is used to read a record.  That way, if no reads
** occur, no unnecessary I/O happens.
*/
case OP_Seek: {    /* in2 */
  int i;
  VdbeCursor *pC;

  i = pOp->p1;
  assert( i>=0 && i<p->nCursor );
  pC = p->apCsr[i];
  assert( pC!=0 );
  if( pC->pCursor!=0 ){
    assert( pC->isTable );
    pC->nullRow = 0;
    pC->movetoTarget = sqlite3VdbeIntValue(pIn2);

** to P2.  If an entry does existing, fall through.  The cursor is left
** pointing to the entry that matches.
**
** See also: Found, NotExists, IsUnique
*/
case OP_NotFound:       /* jump, in3 */
case OP_Found: {        /* jump, in3 */
  int i;
  int alreadyExists;
  VdbeCursor *pC;
  int res;
  UnpackedRecord *pIdxKey;
  char aTempRec[ROUND8(sizeof(UnpackedRecord)) + sizeof(Mem)*3 + 7];

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



    assert( pC->isTable==0 );
    assert( pIn3->flags & MEM_Blob );
    pIdxKey = sqlite3VdbeRecordUnpack(pC->pKeyInfo, pIn3->n, pIn3->z,
                                      aTempRec, sizeof(aTempRec));
    if( pIdxKey==0 ){
      goto no_mem;

** See also: NotFound, NotExists, Found
*/
case OP_IsUnique: {        /* jump, in3 */
  u16 ii;
  VdbeCursor *pCx;
  BtCursor *pCrsr;
  u16 nField;
  Mem *aMem;
  UnpackedRecord r;                  /* B-Tree index search key */
  i64 R;                             /* Rowid stored in register P3 */

  aMem = &p->aMem[pOp->p4.i];
  /* Assert that the values of parameters P1 and P4 are in range. */
  assert( pOp->p4type==P4_INT32 );
  assert( pOp->p4.i>0 && pOp->p4.i<=p->nMem );
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );

  /* Find the index cursor. */
  pCx = p->apCsr[pOp->p1];

      pCrsr = 0;
      break;
    }
  }
  assert( (aMem[nField].flags & MEM_Null)==0 );

  if( pCrsr!=0 ){



    /* Populate the index search key. */
    r.pKeyInfo = pCx->pKeyInfo;
    r.nField = nField + 1;
    r.flags = UNPACKED_PREFIX_SEARCH;
    r.aMem = aMem;

    /* Extract the value of R from register P3. */

** operation assumes the key is an integer and that P1 is a table whereas
** NotFound assumes key is a blob constructed from MakeRecord and
** P1 is an index.
**
** See also: Found, NotFound, IsUnique
*/
case OP_NotExists: {        /* jump, in3 */
  int i;
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int res;
  u64 iKey;

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

    assert( pIn3->flags & MEM_Int );
    assert( p->apCsr[i]->isTable );
    iKey = intToKey(pIn3->u.i);
    rc = sqlite3BtreeMovetoUnpacked(pCrsr, 0, iKey, 0, &res);
    pC->lastRowid = pIn3->u.i;
    pC->rowidIsValid = res==0 ?1:0;
    pC->nullRow = 0;

** generated record number.  No new record numbers are allowed to be less
** than this value.  When this value reaches its maximum, a SQLITE_FULL
** error is generated.  The P3 register is updated with the generated
** record number.  This P3 mechanism is used to help implement the
** AUTOINCREMENT feature.
*/
case OP_NewRowid: {           /* out2-prerelease */
  int i;
  i64 v;
  VdbeCursor *pC;
  int res;
  int rx;
  int cnt;
  i64 x;
  Mem *pMem;

  i = pOp->p1;
  v = 0;
  res = 0;
  rx = SQLITE_OK;
  assert( i>=0 && i<p->nCursor );
  assert( p->apCsr[i]!=0 );
  if( (pC = p->apCsr[i])->pCursor==0 ){
    /* The zero initialization above is all that is needed */
  }else{
    /* The next rowid or record number (different terms for the same
    ** thing) is obtained in a two-step algorithm.

    ** random number generator based on the RC4 algorithm.
    **
    ** To promote locality of reference for repetitive inserts, the
    ** first few attempts at choosing a random rowid pick values just a little
    ** larger than the previous rowid.  This has been shown experimentally
    ** to double the speed of the COPY operation.
    */


    cnt = 0;
    if( (sqlite3BtreeFlags(pC->pCursor)&(BTREE_INTKEY|BTREE_ZERODATA)) !=
          BTREE_INTKEY ){
      rc = SQLITE_CORRUPT_BKPT;
      goto abort_due_to_error;
    }
    assert( (sqlite3BtreeFlags(pC->pCursor) & BTREE_INTKEY)!=0 );

            v++;
          }
        }
      }

#ifndef SQLITE_OMIT_AUTOINCREMENT
      if( pOp->p3 ){

        assert( pOp->p3>0 && pOp->p3<=p->nMem ); /* P3 is a valid memory cell */
        pMem = &p->aMem[pOp->p3];
	REGISTER_TRACE(pOp->p3, pMem);
        sqlite3VdbeMemIntegerify(pMem);
        assert( (pMem->flags & MEM_Int)!=0 );  /* mem(P3) holds an integer */
        if( pMem->u.i==MAX_ROWID || pC->useRandomRowid ){
          rc = SQLITE_FULL;

** value of register P2 will then change.  Make sure this does not
** cause any problems.)
**
** This instruction only works on tables.  The equivalent instruction
** for indices is OP_IdxInsert.
*/
case OP_Insert: {
  Mem *pData;
  Mem *pKey;

  i64 iKey;   /* The integer ROWID or key for the record to be inserted */
  int i;
  VdbeCursor *pC;
  int nZero;
  int seekResult;
  const char *zDb;
  const char *zTbl;
  int op;

  pData = &p->aMem[pOp->p2];
  pKey = &p->aMem[pOp->p3];
  i = pOp->p1;
  assert( i>=0 && i<p->nCursor );
  pC = p->apCsr[i];
  assert( pC!=0 );
  assert( pC->pCursor!=0 || pC->pseudoTable );
  assert( pKey->flags & MEM_Int );
  assert( pC->isTable );
  REGISTER_TRACE(pOp->p2, pData);

      if( !pC->pData ) goto no_mem;
      memcpy(pC->pData, pData->z, pC->nData);
      pC->pData[pC->nData] = 0;
      pC->pData[pC->nData+1] = 0;
    }
    pC->nullRow = 0;
  }else{

    seekResult = ((pOp->p5 & OPFLAG_USESEEKRESULT) ? pC->seekResult : 0);
    if( pData->flags & MEM_Zero ){
      nZero = pData->u.nZero;
    }else{
      nZero = 0;
    }
    sqlite3BtreeSetCachedRowid(pC->pCursor, 0);
    rc = sqlite3BtreeInsert(pC->pCursor, 0, iKey,
                            pData->z, pData->n, nZero,
                            pOp->p5 & OPFLAG_APPEND, seekResult
    );
  }
  
  pC->rowidIsValid = 0;
  pC->deferredMoveto = 0;
  pC->cacheStatus = CACHE_STALE;

  /* Invoke the update-hook if required. */
  if( rc==SQLITE_OK && db->xUpdateCallback && pOp->p4.z ){
    zDb = db->aDb[pC->iDb].zName;
    zTbl = pOp->p4.z;
    op = ((pOp->p5 & OPFLAG_ISUPDATE) ? SQLITE_UPDATE : SQLITE_INSERT);
    assert( pC->isTable );
    db->xUpdateCallback(db->pUpdateArg, op, zDb, zTbl, iKey);
    assert( pC->iDb>=0 );
  }
  break;
}

**
** If P4 is not NULL, then it is the name of the table that P1 is
** pointing to.  The update hook will be invoked, if it exists.
** If P4 is not NULL then the P1 cursor must have been positioned
** using OP_NotFound prior to invoking this opcode.
*/
case OP_Delete: {
  int i;
  i64 iKey;
  VdbeCursor *pC;

  i = pOp->p1;
  iKey = 0;
  assert( i>=0 && i<p->nCursor );
  pC = p->apCsr[i];
  assert( pC!=0 );
  assert( pC->pCursor!=0 );  /* Only valid for real tables, no pseudotables */

  /* If the update-hook will be invoked, set iKey to the rowid of the
  ** row being deleted.

** it is found in the database file.
**
** If the P1 cursor must be pointing to a valid row (not a NULL row)
** of a real table, not a pseudo-table.
*/
case OP_RowKey:
case OP_RowData: {
  int i;
  VdbeCursor *pC;
  BtCursor *pCrsr;
  u32 n;
  i64 n64;

  i = pOp->p1;
  pOut = &p->aMem[pOp->p2];

  /* Note that RowKey and RowData are really exactly the same instruction */
  assert( i>=0 && i<p->nCursor );
  pC = p->apCsr[i];
  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 = (int)n64;
  }else{

** P1 is currently point to.
**
** P1 can be either an ordinary table or a virtual table.  There used to
** be a separate OP_VRowid opcode for use with virtual tables, but this
** one opcode now works for both table types.
*/
case OP_Rowid: {                 /* out2-prerelease */
  int i;
  VdbeCursor *pC;
  i64 v;
  sqlite3_vtab *pVtab;
  const sqlite3_module *pModule;

  i = pOp->p1;
  assert( i>=0 && i<p->nCursor );
  pC = p->apCsr[i];
  assert( pC!=0 );
  if( pC->nullRow ){
    /* Do nothing so that reg[P2] remains NULL */
    break;
  }else if( pC->deferredMoveto ){
    v = pC->movetoTarget;
  }else if( pC->pseudoTable ){
    v = keyToInt(pC->iKey);
#ifndef SQLITE_OMIT_VIRTUALTABLE
  }else if( pC->pVtabCursor ){


    pVtab = pC->pVtabCursor->pVtab;
    pModule = pVtab->pModule;
    assert( pModule->xRowid );
    if( sqlite3SafetyOff(db) ) goto abort_due_to_misuse;
    rc = pModule->xRowid(pC->pVtabCursor, &v);
    sqlite3DbFree(db, p->zErrMsg);
    p->zErrMsg = pVtab->zErrMsg;

/* Opcode: NullRow P1 * * * *
**
** Move the cursor P1 to a null row.  Any OP_Column operations
** that occur while the cursor is on the null row will always
** write a NULL.
*/
case OP_NullRow: {
  int i;
  VdbeCursor *pC;

  i = pOp->p1;
  assert( i>=0 && i<p->nCursor );
  pC = p->apCsr[i];
  assert( pC!=0 );
  pC->nullRow = 1;
  pC->rowidIsValid = 0;
  if( pC->pCursor ){
    sqlite3BtreeClearCursor(pC->pCursor);
  }
  break;
}

/* Opcode: Last P1 P2 * * *
**
** The next use of the Rowid or Column or Next instruction for P1 
** will refer to the last entry in the database table or index.
** If the table or index is empty and P2>0, then jump immediately to P2.
** If P2 is 0 or if the table or index is not empty, fall through
** to the following instruction.
*/
case OP_Last: {        /* jump */
  int i;
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int res;

  i = pOp->p1;
  assert( i>=0 && i<p->nCursor );
  pC = p->apCsr[i];
  assert( pC!=0 );
  pCrsr = pC->pCursor;
  assert( pCrsr!=0 );
  rc = sqlite3BtreeLast(pCrsr, &res);
  pC->nullRow = (u8)res;

** The next use of the Rowid or Column or Next instruction for P1 
** will refer to the first entry in the database table or index.
** If the table or index is empty and P2>0, then jump immediately to P2.
** If P2 is 0 or if the table or index is not empty, fall through
** to the following instruction.
*/
case OP_Rewind: {        /* jump */
  int i;
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int res;

  i = pOp->p1;
  assert( i>=0 && i<p->nCursor );
  pC = p->apCsr[i];
  assert( pC!=0 );
  if( (pCrsr = pC->pCursor)!=0 ){
    rc = sqlite3BtreeFirst(pCrsr, &res);
    pC->atFirst = res==0 ?1:0;
    pC->deferredMoveto = 0;

** P3 is a flag that provides a hint to the b-tree layer that this
** insert is likely to be an append.
**
** This instruction only works for indices.  The equivalent instruction
** for tables is OP_Insert.
*/
case OP_IdxInsert: {        /* in2 */
  int i;
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int nKey;
  const char *zKey;

  i = pOp->p1;
  assert( i>=0 && i<p->nCursor );
  assert( p->apCsr[i]!=0 );
  assert( pIn2->flags & MEM_Blob );
  if( (pCrsr = (pC = p->apCsr[i])->pCursor)!=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)
      );
      assert( pC->deferredMoveto==0 );
      pC->cacheStatus = CACHE_STALE;
    }
  }
  break;
}

/* Opcode: IdxDelete P1 P2 P3 * *
**
** 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: {
  int i;
  VdbeCursor *pC;
  BtCursor *pCrsr;

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

** Write into register P2 an integer which is the last entry in the record at
** the end of the index key pointed to by cursor P1.  This integer should be
** the rowid of the table entry to which this index entry points.
**
** See also: Rowid, MakeRecord.
*/
case OP_IdxRowid: {              /* out2-prerelease */
  int i;
  BtCursor *pCrsr;
  VdbeCursor *pC;
  i64 rowid;

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

** Otherwise fall through to the next instruction.
**
** If P5 is non-zero then the key value is increased by an epsilon prior 
** to the comparison.  This makes the opcode work like IdxLE.
*/
case OP_IdxLT:          /* jump, in3 */
case OP_IdxGE: {        /* jump, in3 */
  int i;
  VdbeCursor *pC;
  int res;
  UnpackedRecord r;

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

** If AUTOVACUUM is disabled then a zero is stored in register P2.
**
** See also: Clear
*/
case OP_Destroy: {     /* out2-prerelease */
  int iMoved;
  int iCnt;

  Vdbe *pVdbe;
  int iDb;
#ifndef SQLITE_OMIT_VIRTUALTABLE
  iCnt = 0;
  for(pVdbe=db->pVdbe; pVdbe; pVdbe = pVdbe->pNext){
    if( pVdbe->magic==VDBE_MAGIC_RUN && pVdbe->inVtabMethod<2 && pVdbe->pc>=0 ){
      iCnt++;
    }
  }
#else
  iCnt = db->activeVdbeCnt;
#endif
  if( iCnt>1 ){
    rc = SQLITE_LOCKED;
    p->errorAction = OE_Abort;
  }else{
    iDb = pOp->p3;
    assert( iCnt==1 );
    assert( (p->btreeMask & (1<<iDb))!=0 );
    rc = sqlite3BtreeDropTable(db->aDb[iDb].pBt, pOp->p1, &iMoved);
    MemSetTypeFlag(pOut, MEM_Int);
    pOut->u.i = iMoved;
#ifndef SQLITE_OMIT_AUTOVACUUM
    if( rc==SQLITE_OK && iMoved!=0 ){

** count is incremented by the number of rows in the table being cleared. 
** If P3 is greater than zero, then the value stored in register P3 is
** also incremented by the number of rows in the table being cleared.
**
** See also: Destroy
*/
case OP_Clear: {
  int nChange;
 
  nChange = 0;
  assert( (p->btreeMask & (1<<pOp->p2))!=0 );
  rc = sqlite3BtreeClearTable(
      db->aDb[pOp->p2].pBt, pOp->p1, (pOp->p3 ? &nChange : 0)
  );
  if( pOp->p3 ){
    p->nChange += nChange;
    if( pOp->p3>0 ){

** P1>1.  Write the root page number of the new table into
** register P2.
**
** See documentation on OP_CreateTable for additional information.
*/
case OP_CreateIndex:            /* out2-prerelease */
case OP_CreateTable: {          /* out2-prerelease */
  int pgno;
  int flags;
  Db *pDb;

  pgno = 0;
  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( (p->btreeMask & (1<<pOp->p1))!=0 );
  pDb = &db->aDb[pOp->p1];
  assert( pDb->pBt!=0 );
  if( pOp->opcode==OP_CreateTable ){
    /* flags = BTREE_INTKEY; */
    flags = BTREE_LEAFDATA|BTREE_INTKEY;

** is false, the SQLITE_MASTER table is only parsed if the rest of the
** schema is already loaded into the symbol table.
**
** This opcode invokes the parser to create a new virtual machine,
** then runs the new virtual machine.  It is thus a re-entrant opcode.
*/
case OP_ParseSchema: {
  int iDb;
  const char *zMaster;
  char *zSql;
  InitData initData;

  iDb = pOp->p1;
  assert( iDb>=0 && iDb<db->nDb );

  /* If pOp->p2 is 0, then this opcode is being executed to read a
  ** single row, for example the row corresponding to a new index
  ** created by this VDBE, from the sqlite_master table. It only
  ** does this if the corresponding in-memory schema is currently
  ** loaded. Otherwise, the new index definition can be loaded along

  ** 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);
    if( zSql==0 ){

/* Opcode: LoadAnalysis P1 * * * *
**
** Read the sqlite_stat1 table for database P1 and load the content
** of that table into the internal index hash table.  This will cause
** the analysis to be used when preparing all subsequent queries.
*/
case OP_LoadAnalysis: {

  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  rc = sqlite3AnalysisLoad(db, pOp->p1);
  break;  
}
#endif /* !defined(SQLITE_OMIT_ANALYZE) && !defined(SQLITE_OMIT_PARSER)  */

/* Opcode: DropTable P1 * * P4 *
**
** Remove the internal (in-memory) data structures that describe

** (b) when P4==-1 there is no need to insert the value, as it will
** never be tested for, and (c) when a value that is part of set X is
** inserted, there is no need to search to see if the same value was
** previously inserted as part of set X (only if it was previously
** inserted as part of some other set).
*/
case OP_RowSetTest: {                     /* jump, in1, in3 */
  int iSet;
  int exists;

  iSet = pOp->p4.i;
  assert( pIn3->flags&MEM_Int );

  /* If there is anything other than a rowset object in memory cell P1,
  ** delete it now and initialize P1 with an empty rowset
  */
  if( (pIn1->flags & MEM_RowSet)==0 ){
    sqlite3VdbeMemSetRowSet(pIn1);
    if( (pIn1->flags & MEM_RowSet)==0 ) goto no_mem;
  }

  assert( pOp->p4type==P4_INT32 );
  assert( iSet==-1 || iSet>=0 );
  if( iSet ){

    exists = sqlite3RowSetTest(pIn1->u.pRowSet, 
                               (u8)(iSet>=0 ? iSet & 0xf : 0xff),
                               pIn3->u.i);
    if( exists ){
      pc = pOp->p2 - 1;
      break;
    }

/* Opcode: ContextPush * * * 
**
** Save the current Vdbe context such that it can be restored by a ContextPop
** opcode. The context stores the last insert row id, the last statement change
** count, and the current statement change count.
*/
case OP_ContextPush: {
  int i;
  Context *pContext;

  i = p->contextStackTop++;
  assert( i>=0 );
  /* FIX ME: This should be allocated as part of the vdbe at compile-time */
  if( i>=p->contextStackDepth ){
    p->contextStackDepth = i+1;
    p->contextStack = sqlite3DbReallocOrFree(db, p->contextStack,
                                          sizeof(Context)*(i+1));
    if( p->contextStack==0 ) goto no_mem;

/* Opcode: ContextPop * * * 
**
** Restore the Vdbe context to the state it was in when contextPush was last
** executed. The context stores the last insert row id, the last statement
** change count, and the current statement change count.
*/
case OP_ContextPop: {
  Context *pContext;
  pContext = &p->contextStack[--p->contextStackTop];
  assert( p->contextStackTop>=0 );
  db->lastRowid = pContext->lastRowid;
  p->nChange = pContext->nChange;
  break;
}
#endif /* #ifndef SQLITE_OMIT_TRIGGER */

** structure that specifies the function.  Use register
** P3 as the accumulator.
**
** The P5 arguments are taken from register P2 and its
** successors.
*/
case OP_AggStep: {
  int n;
  int i;
  Mem *pMem, *pRec;
  sqlite3_context ctx;
  sqlite3_value **apVal;

  n = pOp->p5;
  assert( n>=0 );
  pRec = &p->aMem[pOp->p2];
  apVal = p->apArg;
  assert( apVal || n==0 );
  for(i=0; i<n; i++, pRec++){
    apVal[i] = pRec;
    storeTypeInfo(pRec, encoding);

**
** P2 contains the root-page of the table to lock.
**
** P4 contains a pointer to the name of the table being locked. This is only
** used to generate an error message if the lock cannot be obtained.
*/
case OP_TableLock: {
  int p1;
  u8 isWriteLock;

  p1 = pOp->p1; 
  isWriteLock = (u8)pOp->p3;
  assert( p1>=0 && p1<db->nDb );
  assert( (p->btreeMask & (1<<p1))!=0 );
  assert( isWriteLock==0 || isWriteLock==1 );
  rc = sqlite3BtreeLockTable(db->aDb[p1].pBt, pOp->p2, isWriteLock);
  if( (rc&0xFF)==SQLITE_LOCKED ){
    const char *z = pOp->p4.z;
    sqlite3SetString(&p->zErrMsg, db, "database table is locked: %s", z);

** xBegin method for that table.
**
** Also, whether or not P4 is set, check that this is not being called from
** within a callback to a virtual table xSync() method. If it is, the error
** code will be set to SQLITE_LOCKED.
*/
case OP_VBegin: {
  sqlite3_vtab *pVtab;
  pVtab = pOp->p4.pVtab;
  rc = sqlite3VtabBegin(db, pVtab);
  if( pVtab ){
    sqlite3DbFree(db, p->zErrMsg);
    p->zErrMsg = pVtab->zErrMsg;
    pVtab->zErrMsg = 0;
  }
  break;

/* Opcode: VOpen P1 * * P4 *
**
** P4 is a pointer to a virtual table object, an sqlite3_vtab structure.
** P1 is a cursor number.  This opcode opens a cursor to the virtual
** table and stores that cursor in P1.
*/
case OP_VOpen: {
  VdbeCursor *pCur;
  sqlite3_vtab_cursor *pVtabCursor;

  sqlite3_vtab *pVtab;
  sqlite3_module *pModule;

  pCur = 0;
  pVtabCursor = 0;
  pVtab = pOp->p4.pVtab;
  pModule = (sqlite3_module *)pVtab->pModule;
  assert(pVtab && pModule);
  if( sqlite3SafetyOff(db) ) goto abort_due_to_misuse;
  rc = pModule->xOpen(pVtab, &pVtabCursor);
  sqlite3DbFree(db, p->zErrMsg);
  p->zErrMsg = pVtab->zErrMsg;
  pVtab->zErrMsg = 0;
  if( sqlite3SafetyOn(db) ) goto abort_due_to_misuse;

**
** A jump is made to P2 if the result set after filtering would be empty.
*/
case OP_VFilter: {   /* jump */
  int nArg;
  int iQuery;
  const sqlite3_module *pModule;
  Mem *pQuery;
  Mem *pArgc;
  sqlite3_vtab_cursor *pVtabCursor;
  sqlite3_vtab *pVtab;

  VdbeCursor *pCur;
  int res;
  int i;
  Mem **apArg;

  pQuery = &p->aMem[pOp->p3];
  pArgc = &pQuery[1];
  pCur = p->apCsr[pOp->p1];
  REGISTER_TRACE(pOp->p3, pQuery);
  assert( pCur->pVtabCursor );
  pVtabCursor = pCur->pVtabCursor;
  pVtab = pVtabCursor->pVtab;
  pModule = pVtab->pModule;

  /* Grab the index number and argc parameters */
  assert( (pQuery->flags&MEM_Int)!=0 && pArgc->flags==MEM_Int );
  nArg = (int)pArgc->u.i;
  iQuery = (int)pQuery->u.i;

  /* Invoke the xFilter method */
  {
    res = 0;

    apArg = p->apArg;
    for(i = 0; i<nArg; i++){
      apArg[i] = &pArgc[i+1];
      storeTypeInfo(apArg[i], 0);
    }

    if( sqlite3SafetyOff(db) ) goto abort_due_to_misuse;
    sqlite3VtabLock(pVtab);

** jump to instruction P2.  Or, if the virtual table has reached
** the end of its result set, then fall through to the next instruction.
*/
case OP_VNext: {   /* jump */
  sqlite3_vtab *pVtab;
  const sqlite3_module *pModule;
  int res = 0;
  VdbeCursor *pCur;

  pCur = p->apCsr[pOp->p1];
  assert( pCur->pVtabCursor );
  if( pCur->nullRow ){
    break;
  }
  pVtab = pCur->pVtabCursor->pVtab;
  pModule = pVtab->pModule;
  assert( pModule->xNext );

/* Opcode: VRename P1 * * P4 *
**
** P4 is a pointer to a virtual table object, an sqlite3_vtab structure.
** This opcode invokes the corresponding xRename method. The value
** in register P1 is passed as the zName argument to the xRename method.
*/
case OP_VRename: {
  sqlite3_vtab *pVtab;
  Mem *pName;

  pVtab = pOp->p4.pVtab;
  pName = &p->aMem[pOp->p1];
  assert( pVtab->pModule->xRename );
  REGISTER_TRACE(pOp->p1, pName);

  Stringify(pName, encoding);

  if( sqlite3SafetyOff(db) ) goto abort_due_to_misuse;
  sqlite3VtabLock(pVtab);

** a row to delete.
**
** P1 is a boolean flag. If it is set to true and the xUpdate call
** is successful, then the value returned by sqlite3_last_insert_rowid() 
** is set to the value of the rowid for the row just inserted.
*/
case OP_VUpdate: {
  sqlite3_vtab *pVtab;
  sqlite3_module *pModule;
  int nArg;
  int i;
  sqlite_int64 rowid;
  Mem **apArg;
  Mem *pX;

  pVtab = pOp->p4.pVtab;
  pModule = (sqlite3_module *)pVtab->pModule;
  nArg = pOp->p2;
  assert( pOp->p4type==P4_VTAB );
  if( pModule->xUpdate==0 ){
    sqlite3SetString(&p->zErrMsg, db, "read-only table");
    rc = SQLITE_ERROR;
  }else{


    apArg = p->apArg;
    pX = &p->aMem[pOp->p3];
    for(i=0; i<nArg; i++){
      storeTypeInfo(pX, 0);
      apArg[i] = pX;
      pX++;
    }
    if( sqlite3SafetyOff(db) ) goto abort_due_to_misuse;
    sqlite3VtabLock(pVtab);

#ifndef  SQLITE_OMIT_PAGER_PRAGMAS
/* Opcode: Pagecount P1 P2 * * *
**
** Write the current number of pages in database P1 to memory cell P2.
*/
case OP_Pagecount: {            /* out2-prerelease */
  int p1;
  int nPage;
  Pager *pPager;

  p1 = pOp->p1; 
  pPager = sqlite3BtreePager(db->aDb[p1].pBt);
  rc = sqlite3PagerPagecount(pPager, &nPage);
  if( rc==SQLITE_OK ){
    pOut->flags = MEM_Int;
    pOut->u.i = nPage;
  }
  break;
}
#endif

#ifndef SQLITE_OMIT_TRACE
/* Opcode: Trace * * * P4 *
**
** If tracing is enabled (by the sqlite3_trace()) interface, then
** the UTF-8 string contained in P4 is emitted on the trace callback.
*/
case OP_Trace: {
  char *zTrace;

  zTrace = (pOp->p4.z ? pOp->p4.z : p->zSql);
  if( zTrace ){
    if( db->xTrace ){
      db->xTrace(db->pTraceArg, zTrace);
    }
#ifdef SQLITE_DEBUG
    if( (db->flags & SQLITE_SqlTrace)!=0 ){
      sqlite3DebugPrintf("SQL-trace: %s\n", zTrace);

#!/usr/bin/tcl
#
# This script makes modifications to the vdbe.c source file which reduce
# the amount of stack space required by the sqlite3VdbeExec() routine.
#
# The modifications performed by this script are optional.  The vdbe.c
# source file will compile correctly with and without the modifications
# performed by this script.  And all routines within vdbe.c will compute
# the same result.  The modifications made by this script merely help
# the C compiler to generate code for sqlite3VdbeExec() that uses less
# stack space.
#
# Script usage:
#
#          mv vdbe.c vdbe.c.template
#          tclsh vdbe-compress.tcl <vdbe.c.template >vdbe.c
#
# Modifications made:
#
# All modifications are within the sqlite3VdbeExec() function.  The
# modifications seek to reduce the amount of stack space allocated by
# this routine by moving local variable declarations out of individual
# opcode implementations and into a single large union.  The union contains
# a separate structure for each opcode and that structure contains the
# local variables used by that opcode.  In this way, the total amount
# of stack space required by sqlite3VdbeExec() is reduced from the
# sum of all local variables to the maximum of the local variable space
# required for any single opcode.
#
# In order to be recognized by this script, local variables must appear
# on the first line after the open curly-brace that begins a new opcode
# implementation.  Local variables must not have initializers, though they
# may be commented.
#
# The union definition is inserted in place of a special marker comment
# in the preamble to the sqlite3VdbeExec() implementation.
#
#############################################################################
#
set beforeUnion {}   ;# C code before union
set unionDef {}      ;# C code of the union
set afterUnion {}    ;# C code after the union
set sCtr 0           ;# Context counter

# Read program text up to the spot where the union should be
# inserted.
#
while {![eof stdin]} {
  set line [gets stdin]
  if {[regexp {INSERT STACK UNION HERE} $line]} break
  append beforeUnion $line\n
}

# Process the remaining text.  Build up the union definition as we go.
#
set vlist {}
set seenDecl 0
set namechars {abcdefghijklmnopqrstuvwxyz}
set nnc [string length $namechars]
while {![eof stdin]} {
  set line [gets stdin]
  if {[regexp "^case (OP_\\w+): \173" $line all operator]} {
    append afterUnion $line\n
    set vlist {}
    while {![eof stdin]} {
      set line [gets stdin]
      if {[regexp {^ +(const )?\w+ \*?(\w+)(\[.*\])?;} $line \
           all constKeyword vname notused1]} {
        if {!$seenDecl} {
          set sname {}
          append sname [string index $namechars [expr {$sCtr/$nnc}]]
          append sname [string index $namechars [expr {$sCtr%$nnc}]]
          incr sCtr
          append unionDef "    struct ${operator}_stack_vars \173\n"
          append afterUnion \
             "#if 0  /* local variables moved into u.$sname */\n"
          set seenDecl 1
        }
        append unionDef "    $line\n"
        append afterUnion $line\n
        lappend vlist $vname
      } else {
        break
      }
    }
    if {$seenDecl} {
      append unionDef   "    \175 $sname;\n"
      append afterUnion "#endif /* local variables moved into u.$sname */\n"
    }
    set seenDecl 0
  }
  if {[regexp "^\175" $line]} {
    append afterUnion $line\n
    set vlist {}
  } elseif {[llength $vlist]>0} {
    append line " "
    foreach v $vlist {
      regsub -all "(\[^a-zA-Z0-9>.\])${v}(\\W)" $line "\\1u.$sname.$v\\2" line
    }
    append afterUnion [string trimright $line]\n
  } elseif {$line=="" && [eof stdin]} {
    # no-op
  } else {
    append afterUnion $line\n
  }
}

# Output the resulting text.
#
puts -nonewline $beforeUnion
puts "  /********************************************************************"
puts "  ** Automatically generated code"
puts "  **"
puts "  ** The following union is automatically generated by the"
puts "  ** vdbe-compress.tcl script.  The purpose of this union is to"
puts "  ** reduce the amount of stack space required by this function."
puts "  ** See comments in the vdbe-compress.tcl script for details."
puts "  */"
puts "  union vdbeExecUnion \173"
puts -nonewline $unionDef
puts "  \175 u;"
puts "  /* End automatically generated code"
puts "  ********************************************************************/"
puts -nonewline $afterUnion