SQLite

**
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** 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 1.252 2004/01/30 14:49:17 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*

  return pElem ? sqliteHashData(pElem) : 0;
}

/*
** Convert the given stack entity into a string if it isn't one
** already.
*/
#define Stringify(P,I) if((aStack[I].flags & MEM_Str)==0){hardStringify(P,I);}
static int hardStringify(Vdbe *p, int i){
  Mem *pStack = &p->aStack[i];
  int fg = pStack->flags;
  if( fg & MEM_Real ){
    sqlite_snprintf(sizeof(pStack->zShort),pStack->zShort,"%.15g",pStack->r);
  }else if( fg & MEM_Int ){
    sqlite_snprintf(sizeof(pStack->zShort),pStack->zShort,"%d",pStack->i);
  }else{
    pStack->zShort[0] = 0;
  }
  p->aStack[i].z = pStack->zShort;
  pStack->n = strlen(pStack->zShort)+1;
  pStack->flags = MEM_Str;
  return 0;
}

/*
** Convert the given stack entity into a string that has been obtained
** from sqliteMalloc().  This is different from Stringify() above in that
** Stringify() will use the NBFS bytes of static string space if the string
** will fit but this routine always mallocs for space.
** Return non-zero if we run out of memory.
*/
#define Dynamicify(P,I) ((aStack[I].flags & MEM_Dyn)==0 ? hardDynamicify(P,I):0)
static int hardDynamicify(Vdbe *p, int i){
  Mem *pStack = &p->aStack[i];
  int fg = pStack->flags;
  char *z;
  if( (fg & MEM_Str)==0 ){
    hardStringify(p, i);
  }
  assert( (fg & MEM_Dyn)==0 );
  z = sqliteMallocRaw( pStack->n );
  if( z==0 ) return 1;
  memcpy(z, p->aStack[i].z, pStack->n);
  p->aStack[i].z = z;
  pStack->flags |= MEM_Dyn;
  return 0;
}

/*
** An ephemeral string value (signified by the MEM_Ephem flag) contains
** a pointer to a dynamically allocated string where some other entity
** is responsible for deallocating that string.  Because the stack entry
** does not control the string, it might be deleted without the stack
** entry knowing it.
**
** This routine converts an ephemeral string into a dynamically allocated
** string that the stack entry itself controls.  In other words, it
** converts an MEM_Ephem string into an MEM_Dyn string.
*/
#define Deephemeralize(P,I) \
   if( ((P)->aStack[I].flags&MEM_Ephem)!=0 && hardDeephem(P,I) ){ goto no_mem;}
static int hardDeephem(Vdbe *p, int i){
  Mem *pStack = &p->aStack[i];
  char *z;
  assert( (pStack->flags & MEM_Ephem)!=0 );
  z = sqliteMallocRaw( pStack->n );
  if( z==0 ) return 1;
  memcpy(z, pStack->z, pStack->n);
  pStack->z = z;
  pStack->flags &= ~MEM_Ephem;
  pStack->flags |= MEM_Dyn;
  return 0;
}

/*
** Release the memory associated with the given stack level

*/

#define Release(P,I)  if((P)->aStack[I].flags&MEM_Dyn){ hardRelease(P,I); }



static void hardRelease(Vdbe *p, int i){



  sqliteFree(p->aStack[i].z);


  p->aStack[i].z = 0;
  p->aStack[i].flags &= ~(MEM_Str|MEM_Dyn|MEM_Static|MEM_Ephem);
}

/*
** Return TRUE if zNum is a 32-bit signed integer and write
** the value of the integer into *pNum.  If zNum is not an integer
** or is an integer that is too large to be expressed with just 32
** bits, then return false.

/*
** Convert the given stack entity into a integer if it isn't one
** already.
**
** Any prior string or real representation is invalidated.  
** NULLs are converted into 0.
*/
#define Integerify(P,I) \
    if(((P)->aStack[(I)].flags&MEM_Int)==0){ hardIntegerify(P,I); }
static void hardIntegerify(Vdbe *p, int i){
  if( p->aStack[i].flags & MEM_Real ){
    p->aStack[i].i = (int)p->aStack[i].r;
    Release(p, i);
  }else if( p->aStack[i].flags & MEM_Str ){
    toInt(p->aStack[i].z, &p->aStack[i].i);
    Release(p, i);
  }else{
    p->aStack[i].i = 0;
  }
  p->aStack[i].flags = MEM_Int;
}

/*
** Get a valid Real representation for the given stack element.
**
** Any prior string or integer representation is retained.
** NULLs are converted into 0.0.
*/
#define Realify(P,I) \
    if(((P)->aStack[(I)].flags&MEM_Real)==0){ hardRealify(P,I); }
static void hardRealify(Vdbe *p, int i){
  if( p->aStack[i].flags & MEM_Str ){
    p->aStack[i].r = sqliteAtoF(p->aStack[i].z);
  }else if( p->aStack[i].flags & MEM_Int ){
    p->aStack[i].r = p->aStack[i].i;
  }else{
    p->aStack[i].r = 0.0;
  }
  p->aStack[i].flags |= MEM_Real;
}

/*
** The parameters are pointers to the head of two sorted lists
** of Sorter structures.  Merge these two lists together and return
** a single sorted list.  This routine forms the core of the merge-sort
** algorithm.

    pTail->pNext = pLeft;
  }else if( pRight ){
    pTail->pNext = pRight;
  }
  return sHead.pNext;
}

/*
** Code contained within the VERIFY() macro is not needed for correct
** execution.  It is there only to catch errors.  So when we compile
** with NDEBUG=1, the VERIFY() code is omitted.
*/
#ifdef NDEBUG
# define VERIFY(X)
#else
# define VERIFY(X) X
#endif

/*
** The following routine works like a replacement for the standard
** library routine fgets().  The difference is in how end-of-line (EOL)
** is handled.  Standard fgets() uses LF for EOL under unix, CRLF
** under windows, and CR under mac.  This routine accepts any of these
** character sequences as an EOL mark.  The EOL mark is replaced by
** a single LF character in zBuf.

int sqliteVdbeExec(
  Vdbe *p                    /* The VDBE */
){
  int pc;                    /* The program counter */
  Op *pOp;                   /* Current operation */
  int rc = SQLITE_OK;        /* Value to return */
  sqlite *db = p->db;        /* The database */
  Mem *aStack = p->aStack;   /* The operand stack */
  char zBuf[100];            /* Space to sprintf() an integer */
#ifdef VDBE_PROFILE
  unsigned long long 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

  if( p->magic!=VDBE_MAGIC_RUN ) return SQLITE_MISUSE;
  assert( db->magic==SQLITE_MAGIC_BUSY );
  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY );
  p->rc = SQLITE_OK;
  assert( p->explain==0 );
  if( sqlite_malloc_failed ) goto no_mem;

  if( p->popStack ){
    sqliteVdbePopStack(p, p->popStack);
    p->popStack = 0;
  }
  for(pc=p->pc; rc==SQLITE_OK; pc++){
    assert( pc>=0 && pc<p->nOp );
    assert( p->tos<=pc );
#ifdef VDBE_PROFILE
    origPc = pc;
    start = hwtime();
#endif
    pOp = &p->aOp[pc];

    /* Only allow tracing if NDEBUG is not defined.

**
** There is an implied "Halt 0 0 0" instruction inserted at the very end of
** every program.  So a jump past the last instruction of the program
** is the same as executing Halt.
*/
case OP_Halt: {
  p->magic = VDBE_MAGIC_HALT;

  if( pOp->p1!=SQLITE_OK ){
    p->rc = pOp->p1;
    p->errorAction = pOp->p2;
    if( pOp->p3 ){
      sqliteSetString(&p->zErrMsg, pOp->p3, (char*)0);
    }
    return SQLITE_ERROR;
  }else{
    p->rc = SQLITE_OK;
    return SQLITE_DONE;
  }
}

/* Opcode: Integer P1 * P3
**
** The integer value P1 is pushed onto the stack.  If P3 is not zero
** then it is assumed to be a string representation of the same integer.
*/
case OP_Integer: {
  int i = ++p->tos;
  aStack[i].i = pOp->p1;
  aStack[i].flags = MEM_Int;
  if( pOp->p3 ){
    aStack[i].z = pOp->p3;
    aStack[i].flags |= MEM_Str | MEM_Static;
    aStack[i].n = strlen(pOp->p3)+1;
  }
  break;
}

/* Opcode: String * * P3
**
** The string value P3 is pushed onto the stack.  If P3==0 then a
** NULL is pushed onto the stack.
*/
case OP_String: {
  int i = ++p->tos;
  char *z;
  z = pOp->p3;
  if( z==0 ){
    aStack[i].z = 0;
    aStack[i].n = 0;
    aStack[i].flags = MEM_Null;
  }else{
    aStack[i].z = z;
    aStack[i].n = strlen(z) + 1;
    aStack[i].flags = MEM_Str | MEM_Static;
  }
  break;
}

/* Opcode: Variable P1 * *
**
** Push the value of variable P1 onto the stack.  A variable is
** an unknown in the original SQL string as handed to sqlite_compile().
** Any occurance of the '?' character in the original SQL is considered
** a variable.  Variables in the SQL string are number from left to
** right beginning with 1.  The values of variables are set using the
** sqlite_bind() API.
*/
case OP_Variable: {
  int i = ++p->tos;
  int j = pOp->p1 - 1;

  if( j>=0 && j<p->nVar && p->azVar[j]!=0 ){
    aStack[i].z = p->azVar[j];
    aStack[i].n = p->anVar[j];
    aStack[i].flags = MEM_Str | MEM_Static;
  }else{
    aStack[i].z = 0;
    aStack[i].n = 0;
    aStack[i].flags = MEM_Null;
  }
  break;
}

/* Opcode: Pop P1 * *
**
** P1 elements are popped off of the top of stack and discarded.
*/
case OP_Pop: {
  assert( p->tos+1>=pOp->p1 );
  sqliteVdbePopStack(p, pOp->p1);

  break;
}

/* Opcode: Dup P1 P2 *
**
** A copy of the P1-th element of the stack 
** is made and pushed onto the top of the stack.
** The top of the stack is element 0.  So the
** instruction "Dup 0 0 0" will make a copy of the
** top of the stack.
**
** If the content of the P1-th element is a dynamically
** allocated string, then a new copy of that string
** is made if P2==0.  If P2!=0, then just a pointer
** to the string is copied.
**
** Also see the Pull instruction.
*/
case OP_Dup: {
  int i = p->tos - pOp->p1;

  int j = ++p->tos;
  VERIFY( if( i<0 ) goto not_enough_stack; )
  memcpy(&aStack[j], &aStack[i], sizeof(aStack[i])-NBFS);
  if( aStack[j].flags & MEM_Str ){
    int isStatic = (aStack[j].flags & MEM_Static)!=0;
    if( pOp->p2 || isStatic ){
      aStack[j].z = aStack[i].z;
      aStack[j].flags &= ~MEM_Dyn;
      if( !isStatic ) aStack[j].flags |= MEM_Ephem;
    }else if( aStack[i].n<=NBFS ){
      memcpy(aStack[j].zShort, aStack[i].z, aStack[j].n);
      aStack[j].z = aStack[j].zShort;
      aStack[j].flags &= ~(MEM_Static|MEM_Dyn|MEM_Ephem);
    }else{
      aStack[j].z = sqliteMallocRaw( aStack[j].n );
      if( aStack[j].z==0 ) goto no_mem;
      memcpy(aStack[j].z, aStack[i].z, aStack[j].n);
      aStack[j].flags &= ~(MEM_Static|MEM_Ephem);
      aStack[j].flags |= MEM_Dyn;
    }
  }
  break;
}

/* Opcode: Pull P1 * *
**
** The P1-th element is removed from its current location on 
** the stack and pushed back on top of the stack.  The
** top of the stack is element 0, so "Pull 0 0 0" is
** a no-op.  "Pull 1 0 0" swaps the top two elements of
** the stack.
**
** See also the Dup instruction.
*/
case OP_Pull: {
  int from = p->tos - pOp->p1;
  int to = p->tos;
  int i;
  Mem ts;
  VERIFY( if( from<0 ) goto not_enough_stack; )
  Deephemeralize(p, from);
  ts = aStack[from];
  Deephemeralize(p, to);
  for(i=from; i<to; i++){
    Deephemeralize(p, i+1);
    aStack[i] = aStack[i+1];
    assert( (aStack[i].flags & MEM_Ephem)==0 );



    if( aStack[i].flags & (MEM_Dyn|MEM_Static) ){
      aStack[i].z = aStack[i+1].z;
    }else{
      aStack[i].z = aStack[i].zShort;
    }
  }
  aStack[to] = ts;
  assert( (aStack[to].flags & MEM_Ephem)==0 );



  if( (aStack[to].flags & (MEM_Dyn|MEM_Static))==0 ){
    aStack[to].z = aStack[to].zShort;
  }
  break;
}

/* Opcode: Push P1 * *
**
** Overwrite the value of the P1-th element down on the
** stack (P1==0 is the top of the stack) with the value
** of the top of the stack.  Then pop the top of the stack.
*/
case OP_Push: {
  int from = p->tos;
  int to = p->tos - pOp->p1;

  VERIFY( if( to<0 ) goto not_enough_stack; )
  if( aStack[to].flags & MEM_Dyn ){
    sqliteFree(aStack[to].z);
  }
  Deephemeralize(p, from);

  aStack[to] = aStack[from];
  if( aStack[to].flags & (MEM_Dyn|MEM_Static|MEM_Ephem) ){
    aStack[to].z = aStack[from].z;
  }else{
    aStack[to].z = aStack[to].zShort;
  }
  aStack[from].flags = 0;
  p->tos--;
  break;
}


/* Opcode: ColumnName P1 * P3
**
** P3 becomes the P1-th column name (first is 0).  An array of pointers
** to all column names is passed as the 4th parameter to the callback.
*/
case OP_ColumnName: {
  assert( pOp->p1>=0 && pOp->p1<p->nOp );
  p->azColName[pOp->p1] = pOp->p3;
  p->nCallback = 0;
  break;
}

/* Opcode: Callback P1 * *
**
** Pop P1 values off the stack and form them into an array.  Then
** invoke the callback function using the newly formed array as the
** 3rd parameter.
*/
case OP_Callback: {
  int i = p->tos - pOp->p1 + 1;
  int j;


  VERIFY( if( i<0 ) goto not_enough_stack; )

  for(j=i; j<=p->tos; j++){

    if( aStack[j].flags & MEM_Null ){
      aStack[j].z = 0;
    }else{
      Stringify(p, j);

    }
    p->zArgv[j] = aStack[j].z;
  }
  p->zArgv[p->tos+1] = 0;
  if( p->xCallback==0 ){
    p->azResColumn = &p->zArgv[i];
    p->nResColumn = pOp->p1;
    p->popStack = pOp->p1;
    p->pc = pc + 1;

    return SQLITE_ROW;
  }
  if( sqliteSafetyOff(db) ) goto abort_due_to_misuse; 
  if( p->xCallback(p->pCbArg, pOp->p1, &p->zArgv[i], p->azColName)!=0 ){
    rc = SQLITE_ABORT;
  }
  if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
  p->nCallback++;
  sqliteVdbePopStack(p, pOp->p1);

  if( sqlite_malloc_failed ) goto no_mem;
  break;
}

/* Opcode: NullCallback P1 * *
**
** Invoke the callback function once with the 2nd argument (the

case OP_Concat: {
  char *zNew;
  int nByte;
  int nField;
  int i, j;
  char *zSep;
  int nSep;


  nField = pOp->p1;
  zSep = pOp->p3;
  if( zSep==0 ) zSep = "";
  nSep = strlen(zSep);
  VERIFY( if( p->tos+1<nField ) goto not_enough_stack; )
  nByte = 1 - nSep;
  for(i=p->tos-nField+1; i<=p->tos; i++){

    if( aStack[i].flags & MEM_Null ){
      nByte = -1;
      break;
    }else{
      Stringify(p, i);
      nByte += aStack[i].n - 1 + nSep;
    }
  }
  if( nByte<0 ){
    if( pOp->p2==0 ) sqliteVdbePopStack(p, nField);


    p->tos++;
    aStack[p->tos].flags = MEM_Null;
    aStack[p->tos].z = 0;
    break;
  }
  zNew = sqliteMallocRaw( nByte );
  if( zNew==0 ) goto no_mem;
  j = 0;
  for(i=p->tos-nField+1; i<=p->tos; i++){

    if( (aStack[i].flags & MEM_Null)==0 ){
      memcpy(&zNew[j], aStack[i].z, aStack[i].n-1);
      j += aStack[i].n-1;
    }
    if( nSep>0 && i<p->tos ){
      memcpy(&zNew[j], zSep, nSep);
      j += nSep;
    }
  }
  zNew[j] = 0;
  if( pOp->p2==0 ) sqliteVdbePopStack(p, nField);


  p->tos++;
  aStack[p->tos].n = nByte;
  aStack[p->tos].flags = MEM_Str|MEM_Dyn;
  aStack[p->tos].z = zNew;
  break;
}

/* Opcode: Add * * *
**
** Pop the top two elements from the stack, add them together,
** and push the result back onto the stack.  If either element

** If either operand is NULL, the result is NULL.
*/
case OP_Add:
case OP_Subtract:
case OP_Multiply:
case OP_Divide:
case OP_Remainder: {
  int tos = p->tos;
  int nos = tos - 1;
  VERIFY( if( nos<0 ) goto not_enough_stack; )
  if( ((aStack[tos].flags | aStack[nos].flags) & MEM_Null)!=0 ){

    POPSTACK;
    Release(p, nos);
    aStack[nos].flags = MEM_Null;
  }else if( (aStack[tos].flags & aStack[nos].flags & MEM_Int)==MEM_Int ){
    int a, b;
    a = aStack[tos].i;
    b = aStack[nos].i;
    switch( pOp->opcode ){
      case OP_Add:         b += a;       break;
      case OP_Subtract:    b -= a;       break;
      case OP_Multiply:    b *= a;       break;
      case OP_Divide: {
        if( a==0 ) goto divide_by_zero;
        b /= a;
        break;
      }
      default: {
        if( a==0 ) goto divide_by_zero;
        b %= a;
        break;
      }
    }

    POPSTACK;
    Release(p, nos);
    aStack[nos].i = b;
    aStack[nos].flags = MEM_Int;
  }else{
    double a, b;
    Realify(p, tos);
    Realify(p, nos);
    a = aStack[tos].r;
    b = aStack[nos].r;
    switch( pOp->opcode ){
      case OP_Add:         b += a;       break;
      case OP_Subtract:    b -= a;       break;
      case OP_Multiply:    b *= a;       break;
      case OP_Divide: {
        if( a==0.0 ) goto divide_by_zero;
        b /= a;
        break;
      }
      default: {
        int ia = (int)a;
        int ib = (int)b;
        if( ia==0.0 ) goto divide_by_zero;
        b = ib % ia;
        break;
      }
    }

    POPSTACK;
    Release(p, nos);
    aStack[nos].r = b;
    aStack[nos].flags = MEM_Real;
  }
  break;

divide_by_zero:
  sqliteVdbePopStack(p, 2);
  p->tos = nos;

  aStack[nos].flags = MEM_Null;
  break;
}

/* Opcode: Function P1 * P3
**
** Invoke a user function (P3 is a pointer to a Function structure that
** defines the function) with P1 string arguments taken from the stack.
** Pop all arguments from the stack and push back the result.
**
** See also: AggFunc
*/
case OP_Function: {
  int n, i;


  sqlite_func ctx;

  n = pOp->p1;
  VERIFY( if( n<0 ) goto bad_instruction; )
  VERIFY( if( p->tos+1<n ) goto not_enough_stack; )
  for(i=p->tos-n+1; i<=p->tos; i++){
    if( aStack[i].flags & MEM_Null ){
      aStack[i].z = 0;
    }else{
      Stringify(p, i);

    }
    p->zArgv[i] = aStack[i].z;
  }
  ctx.pFunc = (FuncDef*)pOp->p3;
  ctx.s.flags = MEM_Null;
  ctx.s.z = 0;
  ctx.isError = 0;
  ctx.isStep = 0;
  if( sqliteSafetyOff(db) ) goto abort_due_to_misuse;
  (*ctx.pFunc->xFunc)(&ctx, n, (const char**)&p->zArgv[p->tos-n+1]);
  if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
  sqliteVdbePopStack(p, n);
  p->tos++;
  aStack[p->tos] = ctx.s;
  if( ctx.s.flags & MEM_Dyn ){
    aStack[p->tos].z = ctx.s.z;
  }else if( ctx.s.flags & MEM_Str ){
    aStack[p->tos].z = aStack[p->tos].zShort;
  }else{
    aStack[p->tos].z = 0;
  }
  if( ctx.isError ){
    sqliteSetString(&p->zErrMsg, 
       aStack[p->tos].z ? aStack[p->tos].z : "user function error", (char*)0);
    rc = SQLITE_ERROR;
  }
  break;
}

/* Opcode: BitAnd * * *
**

** right by N bits where N is the second element on the stack.
** If either operand is NULL, the result is NULL.
*/
case OP_BitAnd:
case OP_BitOr:
case OP_ShiftLeft:
case OP_ShiftRight: {
  int tos = p->tos;
  int nos = tos - 1;
  int a, b;
  VERIFY( if( nos<0 ) goto not_enough_stack; )

  if( (aStack[tos].flags | aStack[nos].flags) & MEM_Null ){
    POPSTACK;
    Release(p,nos);
    aStack[nos].flags = MEM_Null;
    break;
  }
  Integerify(p, tos);
  Integerify(p, nos);
  a = aStack[tos].i;
  b = aStack[nos].i;
  switch( pOp->opcode ){
    case OP_BitAnd:      a &= b;     break;
    case OP_BitOr:       a |= b;     break;
    case OP_ShiftLeft:   a <<= b;    break;
    case OP_ShiftRight:  a >>= b;    break;
    default:   /* CANT HAPPEN */     break;
  }
  POPSTACK;

  Release(p, nos);
  aStack[nos].i = a;
  aStack[nos].flags = MEM_Int;
  break;
}

/* Opcode: AddImm  P1 * *
** 
** Add the value P1 to whatever is on top of the stack.  The result
** is always an integer.
**
** To force the top of the stack to be an integer, just add 0.
*/
case OP_AddImm: {
  int tos = p->tos;
  VERIFY( if( tos<0 ) goto not_enough_stack; )
  Integerify(p, tos);
  aStack[tos].i += pOp->p1;
  break;
}

/* Opcode: ForceInt P1 P2 *
**
** Convert the top of the stack into an integer.  If the current top of
** the stack is not numeric (meaning that is is a NULL or a string that
** does not look like an integer or floating point number) then pop the
** stack and jump to P2.  If the top of the stack is numeric then
** convert it into the least integer that is greater than or equal to its
** current value if P1==0, or to the least integer that is strictly
** greater than its current value if P1==1.
*/
case OP_ForceInt: {
  int tos = p->tos;
  int v;
  VERIFY( if( tos<0 ) goto not_enough_stack; )

  if( (aStack[tos].flags & (MEM_Int|MEM_Real))==0
         && (aStack[tos].z==0 || sqliteIsNumber(aStack[tos].z)==0) ){

    POPSTACK;
    pc = pOp->p2 - 1;
    break;
  }
  if( aStack[tos].flags & MEM_Int ){
    v = aStack[tos].i + (pOp->p1!=0);
  }else{
    Realify(p, tos);
    v = (int)aStack[tos].r;
    if( aStack[tos].r>(double)v ) v++;
    if( pOp->p1 && aStack[tos].r==(double)v ) v++;
  }
  if( aStack[tos].flags & MEM_Dyn ) sqliteFree(aStack[tos].z);
  aStack[tos].z = 0;
  aStack[tos].i = v;
  aStack[tos].flags = MEM_Int;
  break;
}

/* Opcode: MustBeInt P1 P2 *
** 
** Force the top of the stack to be an integer.  If the top of the
** stack is not an integer and cannot be converted into an integer
** with out data loss, then jump immediately to P2, or if P2==0
** raise an SQLITE_MISMATCH exception.
**
** If the top of the stack is not an integer and P2 is not zero and
** P1 is 1, then the stack is popped.  In all other cases, the depth
** of the stack is unchanged.
*/
case OP_MustBeInt: {
  int tos = p->tos;
  VERIFY( if( tos<0 ) goto not_enough_stack; )
  if( aStack[tos].flags & MEM_Int ){
    /* Do nothing */
  }else if( aStack[tos].flags & MEM_Real ){
    int i = aStack[tos].r;
    double r = (double)i;
    if( r!=aStack[tos].r ){
      goto mismatch;
    }
    aStack[tos].i = i;
  }else if( aStack[tos].flags & MEM_Str ){
    int v;
    if( !toInt(aStack[tos].z, &v) ){
      double r;
      if( !sqliteIsNumber(aStack[tos].z) ){
        goto mismatch;
      }
      Realify(p, tos);
      assert( (aStack[tos].flags & MEM_Real)!=0 );
      v = aStack[tos].r;
      r = (double)v;
      if( r!=aStack[tos].r ){
        goto mismatch;
      }
    }
    aStack[tos].i = v;
  }else{
    goto mismatch;
  }
  Release(p, tos);
  aStack[tos].flags = MEM_Int;
  break;

mismatch:
  if( pOp->p2==0 ){
    rc = SQLITE_MISMATCH;
    goto abort_due_to_error;
  }else{
    if( pOp->p1 ) POPSTACK;
    pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: Eq P1 P2 *
**

*/
case OP_Eq:
case OP_Ne:
case OP_Lt:
case OP_Le:
case OP_Gt:
case OP_Ge: {
  int tos = p->tos;
  int nos = tos - 1;
  int c, v;
  int ft, fn;
  VERIFY( if( nos<0 ) goto not_enough_stack; )
  ft = aStack[tos].flags;
  fn = aStack[nos].flags;

  if( (ft | fn) & MEM_Null ){
    POPSTACK;
    POPSTACK;

    if( pOp->p2 ){
      if( pOp->p1 ) pc = pOp->p2-1;
    }else{
      p->tos++;
      aStack[nos].flags = MEM_Null;
    }
    break;
  }else if( (ft & fn & MEM_Int)==MEM_Int ){
    c = aStack[nos].i - aStack[tos].i;
  }else if( (ft & MEM_Int)!=0 && (fn & MEM_Str)!=0 && toInt(aStack[nos].z,&v) ){
    Release(p, nos);
    aStack[nos].i = v;
    aStack[nos].flags = MEM_Int;
    c = aStack[nos].i - aStack[tos].i;
  }else if( (fn & MEM_Int)!=0 && (ft & MEM_Str)!=0 && toInt(aStack[tos].z,&v) ){
    Release(p, tos);
    aStack[tos].i = v;
    aStack[tos].flags = MEM_Int;
    c = aStack[nos].i - aStack[tos].i;
  }else{
    Stringify(p, tos);
    Stringify(p, nos);
    c = sqliteCompare(aStack[nos].z, aStack[tos].z);
  }
  switch( pOp->opcode ){
    case OP_Eq:    c = c==0;     break;
    case OP_Ne:    c = c!=0;     break;
    case OP_Lt:    c = c<0;      break;
    case OP_Le:    c = c<=0;     break;
    case OP_Gt:    c = c>0;      break;
    default:       c = c>=0;     break;
  }
  POPSTACK;
  POPSTACK;
  if( pOp->p2 ){
    if( c ) pc = pOp->p2-1;
  }else{
    p->tos++;

    aStack[nos].flags = MEM_Int;
    aStack[nos].i = c;
  }
  break;
}
/* INSERT NO CODE HERE!
**
** The opcode numbers are extracted from this source file by doing
**

*/
case OP_StrEq:
case OP_StrNe:
case OP_StrLt:
case OP_StrLe:
case OP_StrGt:
case OP_StrGe: {
  int tos = p->tos;
  int nos = tos - 1;
  int c;
  VERIFY( if( nos<0 ) goto not_enough_stack; )

  if( (aStack[nos].flags | aStack[tos].flags) & MEM_Null ){
    POPSTACK;
    POPSTACK;

    if( pOp->p2 ){
      if( pOp->p1 ) pc = pOp->p2-1;
    }else{
      p->tos++;
      aStack[nos].flags = MEM_Null;
    }
    break;
  }else{
    Stringify(p, tos);
    Stringify(p, nos);
    c = strcmp(aStack[nos].z, aStack[tos].z);
  }
  /* The asserts on each case of the following switch are there to verify
  ** that string comparison opcodes are always exactly 6 greater than the
  ** corresponding numeric comparison opcodes.  The code generator depends
  ** on this fact.
  */
  switch( pOp->opcode ){
    case OP_StrEq:    c = c==0;    assert( pOp->opcode-6==OP_Eq );   break;
    case OP_StrNe:    c = c!=0;    assert( pOp->opcode-6==OP_Ne );   break;
    case OP_StrLt:    c = c<0;     assert( pOp->opcode-6==OP_Lt );   break;
    case OP_StrLe:    c = c<=0;    assert( pOp->opcode-6==OP_Le );   break;
    case OP_StrGt:    c = c>0;     assert( pOp->opcode-6==OP_Gt );   break;
    default:          c = c>=0;    assert( pOp->opcode-6==OP_Ge );   break;
  }
  POPSTACK;
  POPSTACK;
  if( pOp->p2 ){
    if( c ) pc = pOp->p2-1;
  }else{
    p->tos++;
    aStack[nos].flags = MEM_Int;
    aStack[nos].i = c;
  }
  break;
}

/* Opcode: And * * *
**
** Pop two values off the stack.  Take the logical AND of the
** two values and push the resulting boolean value back onto the
** stack. 
*/
/* Opcode: Or * * *
**
** Pop two values off the stack.  Take the logical OR of the
** two values and push the resulting boolean value back onto the
** stack. 
*/
case OP_And:
case OP_Or: {
  int tos = p->tos;
  int nos = tos - 1;
  int v1, v2;    /* 0==TRUE, 1==FALSE, 2==UNKNOWN or NULL */

  VERIFY( if( nos<0 ) goto not_enough_stack; )

  if( aStack[tos].flags & MEM_Null ){
    v1 = 2;
  }else{
    Integerify(p, tos);
    v1 = aStack[tos].i==0;
  }
  if( aStack[nos].flags & MEM_Null ){
    v2 = 2;
  }else{
    Integerify(p, nos);
    v2 = aStack[nos].i==0;
  }
  if( pOp->opcode==OP_And ){
    static const unsigned char and_logic[] = { 0, 1, 2, 1, 1, 1, 2, 1, 2 };
    v1 = and_logic[v1*3+v2];
  }else{
    static const unsigned char or_logic[] = { 0, 0, 0, 0, 1, 2, 0, 2, 2 };
    v1 = or_logic[v1*3+v2];
  }
  POPSTACK;
  Release(p, nos);
  if( v1==2 ){
    aStack[nos].flags = MEM_Null;
  }else{
    aStack[nos].i = v1==0;
    aStack[nos].flags = MEM_Int;
  }
  break;
}

/* Opcode: Negative * * *
**
** Treat the top of the stack as a numeric quantity.  Replace it
** with its additive inverse.  If the top of the stack is NULL
** its value is unchanged.
*/
/* Opcode: AbsValue * * *
**
** Treat the top of the stack as a numeric quantity.  Replace it
** with its absolute value. If the top of the stack is NULL
** its value is unchanged.
*/
case OP_Negative:
case OP_AbsValue: {
  int tos = p->tos;
  VERIFY( if( tos<0 ) goto not_enough_stack; )
  if( aStack[tos].flags & MEM_Real ){
    Release(p, tos);
    if( pOp->opcode==OP_Negative || aStack[tos].r<0.0 ){
      aStack[tos].r = -aStack[tos].r;
    }
    aStack[tos].flags = MEM_Real;
  }else if( aStack[tos].flags & MEM_Int ){
    Release(p, tos);
    if( pOp->opcode==OP_Negative ||  aStack[tos].i<0 ){
      aStack[tos].i = -aStack[tos].i;
    }
    aStack[tos].flags = MEM_Int;
  }else if( aStack[tos].flags & MEM_Null ){
    /* Do nothing */
  }else{
    Realify(p, tos);
    Release(p, tos);
    if( pOp->opcode==OP_Negative ||  aStack[tos].r<0.0 ){
      aStack[tos].r = -aStack[tos].r;
    }
    aStack[tos].flags = MEM_Real;
  }
  break;
}

/* Opcode: Not * * *
**
** Interpret the top of the stack as a boolean value.  Replace it
** with its complement.  If the top of the stack is NULL its value
** is unchanged.
*/
case OP_Not: {
  int tos = p->tos;
  VERIFY( if( p->tos<0 ) goto not_enough_stack; )
  if( aStack[tos].flags & MEM_Null ) break;  /* Do nothing to NULLs */
  Integerify(p, tos);
  Release(p, tos);
  aStack[tos].i = !aStack[tos].i;
  aStack[tos].flags = MEM_Int;

  break;
}

/* Opcode: BitNot * * *
**
** Interpret the top of the stack as an value.  Replace it
** with its ones-complement.  If the top of the stack is NULL its
** value is unchanged.
*/
case OP_BitNot: {
  int tos = p->tos;
  VERIFY( if( p->tos<0 ) goto not_enough_stack; )
  if( aStack[tos].flags & MEM_Null ) break;  /* Do nothing to NULLs */
  Integerify(p, tos);
  Release(p, tos);
  aStack[tos].i = ~aStack[tos].i;
  aStack[tos].flags = MEM_Int;

  break;
}

/* Opcode: Noop * * *
**
** Do nothing.  This instruction is often useful as a jump
** destination.

**
** If the value popped of the stack is NULL, then take the jump if P1
** is true and fall through if P1 is false.
*/
case OP_If:
case OP_IfNot: {
  int c;
  VERIFY( if( p->tos<0 ) goto not_enough_stack; )
  if( aStack[p->tos].flags & MEM_Null ){
    c = pOp->p1;
  }else{
    Integerify(p, p->tos);
    c = aStack[p->tos].i;
    if( pOp->opcode==OP_IfNot ) c = !c;
  }

  POPSTACK;
  if( c ) pc = pOp->p2-1;
  break;
}

/* Opcode: IsNull P1 P2 *
**
** If any of the top abs(P1) values on the stack are NULL, then jump
** to P2.  Pop the stack P1 times if P1>0.   If P1<0 leave the stack
** unchanged.
*/
case OP_IsNull: {
  int i, cnt;

  cnt = pOp->p1;
  if( cnt<0 ) cnt = -cnt;
  VERIFY( if( p->tos+1-cnt<0 ) goto not_enough_stack; )

  for(i=0; i<cnt; i++){
    if( aStack[p->tos-i].flags & MEM_Null ){
      pc = pOp->p2-1;
      break;
    }
  }
  if( pOp->p1>0 ) sqliteVdbePopStack(p, cnt);
  break;
}

/* Opcode: NotNull P1 P2 *
**
** Jump to P2 if the top P1 values on the stack are all not NULL.  Pop the
** stack if P1 times if P1 is greater than zero.  If P1 is less than
** zero then leave the stack unchanged.
*/
case OP_NotNull: {
  int i, cnt;
  cnt = pOp->p1;
  if( cnt<0 ) cnt = -cnt;
  VERIFY( if( p->tos+1-cnt<0 ) goto not_enough_stack; )
  for(i=0; i<cnt && (aStack[p->tos-i].flags & MEM_Null)==0; i++){}
  if( i>=cnt ) pc = pOp->p2-1;
  if( pOp->p1>0 ) sqliteVdbePopStack(p, cnt);
  break;
}

/* Opcode: MakeRecord P1 P2 *
**
** Convert the top P1 entries of the stack into a single entry
** suitable for use as a data record in a database table.  The

case OP_MakeRecord: {
  char *zNewRecord;
  int nByte;
  int nField;
  int i, j;
  int idxWidth;
  u32 addr;

  int addUnique = 0;   /* True to cause bytes to be added to make the
                       ** generated record distinct */
  char zTemp[NBFS];    /* Temp space for small records */

  /* Assuming the record contains N fields, the record format looks
  ** like this:
  **

  **
  ** Each of the idx() entries is either 1, 2, or 3 bytes depending on
  ** how big the total record is.  Idx(0) contains the offset to the start
  ** of data(0).  Idx(k) contains the offset to the start of data(k).
  ** Idx(N) contains the total number of bytes in the record.
  */
  nField = pOp->p1;
  VERIFY( if( p->tos+1<nField ) goto not_enough_stack; )

  nByte = 0;
  for(i=p->tos-nField+1; i<=p->tos; i++){
    if( (aStack[i].flags & MEM_Null) ){
      addUnique = pOp->p2;
    }else{
      Stringify(p, i);
      nByte += aStack[i].n;
    }
  }
  if( addUnique ) nByte += sizeof(p->uniqueCnt);
  if( nByte + nField + 1 < 256 ){
    idxWidth = 1;
  }else if( nByte + 2*nField + 2 < 65536 ){
    idxWidth = 2;

    zNewRecord = zTemp;
  }else{
    zNewRecord = sqliteMallocRaw( nByte );
    if( zNewRecord==0 ) goto no_mem;
  }
  j = 0;
  addr = idxWidth*(nField+1) + addUnique*sizeof(p->uniqueCnt);
  for(i=p->tos-nField+1; i<=p->tos; i++){
    zNewRecord[j++] = addr & 0xff;
    if( idxWidth>1 ){
      zNewRecord[j++] = (addr>>8)&0xff;
      if( idxWidth>2 ){
        zNewRecord[j++] = (addr>>16)&0xff;
      }
    }
    if( (aStack[i].flags & MEM_Null)==0 ){
      addr += aStack[i].n;
    }
  }
  zNewRecord[j++] = addr & 0xff;
  if( idxWidth>1 ){
    zNewRecord[j++] = (addr>>8)&0xff;
    if( idxWidth>2 ){
      zNewRecord[j++] = (addr>>16)&0xff;
    }
  }
  if( addUnique ){
    memcpy(&zNewRecord[j], &p->uniqueCnt, sizeof(p->uniqueCnt));
    p->uniqueCnt++;
    j += sizeof(p->uniqueCnt);
  }
  for(i=p->tos-nField+1; i<=p->tos; i++){
    if( (aStack[i].flags & MEM_Null)==0 ){
      memcpy(&zNewRecord[j], aStack[i].z, aStack[i].n);
      j += aStack[i].n;
    }
  }
  sqliteVdbePopStack(p, nField);
  p->tos++;
  aStack[p->tos].n = nByte;
  if( nByte<=NBFS ){
    assert( zNewRecord==zTemp );
    memcpy(aStack[p->tos].zShort, zTemp, nByte);
    aStack[p->tos].z = aStack[p->tos].zShort;
    aStack[p->tos].flags = MEM_Str;
  }else{
    assert( zNewRecord!=zTemp );

    aStack[p->tos].flags = MEM_Str | MEM_Dyn;
    aStack[p->tos].z = zNewRecord;
  }
  break;
}

/* Opcode: MakeKey P1 P2 P3
**
** Convert the top P1 entries of the stack into a single entry suitable

case OP_MakeKey: {
  char *zNewKey;
  int nByte;
  int nField;
  int addRowid;
  int i, j;
  int containsNull = 0;

  char zTemp[NBFS];

  addRowid = pOp->opcode==OP_MakeIdxKey;
  nField = pOp->p1;
  VERIFY( if( p->tos+1+addRowid<nField ) goto not_enough_stack; )

  nByte = 0;
  for(j=0, i=p->tos-nField+1; i<=p->tos; i++, j++){
    int flags = aStack[i].flags;
    int len;
    char *z;
    if( flags & MEM_Null ){
      nByte += 2;
      containsNull = 1;
    }else if( pOp->p3 && pOp->p3[j]=='t' ){
      Stringify(p, i);
      aStack[i].flags &= ~(MEM_Int|MEM_Real);
      nByte += aStack[i].n+1;
    }else if( (flags & (MEM_Real|MEM_Int))!=0 || sqliteIsNumber(aStack[i].z) ){
      if( (flags & (MEM_Real|MEM_Int))==MEM_Int ){
        aStack[i].r = aStack[i].i;
      }else if( (flags & (MEM_Real|MEM_Int))==0 ){
        aStack[i].r = sqliteAtoF(aStack[i].z);
      }
      Release(p, i);
      z = aStack[i].zShort;
      sqliteRealToSortable(aStack[i].r, z);
      len = strlen(z);
      aStack[i].z = 0;
      aStack[i].flags = MEM_Real;
      aStack[i].n = len+1;
      nByte += aStack[i].n+1;
    }else{
      nByte += aStack[i].n+1;
    }
  }
  if( nByte+sizeof(u32)>MAX_BYTES_PER_ROW ){
    rc = SQLITE_TOOBIG;
    goto abort_due_to_error;
  }
  if( addRowid ) nByte += sizeof(u32);
  if( nByte<=NBFS ){
    zNewKey = zTemp;
  }else{
    zNewKey = sqliteMallocRaw( nByte );
    if( zNewKey==0 ) goto no_mem;
  }
  j = 0;
  for(i=p->tos-nField+1; i<=p->tos; i++){

    if( aStack[i].flags & MEM_Null ){
      zNewKey[j++] = 'a';
      zNewKey[j++] = 0;
    }else{
      if( aStack[i].flags & (MEM_Int|MEM_Real) ){
        zNewKey[j++] = 'b';


      }else{

        zNewKey[j++] = 'c';
      }
      /*** Is this right? ****/
      memcpy(&zNewKey[j],aStack[i].z?aStack[i].z:aStack[i].zShort,aStack[i].n);
      j += aStack[i].n;
    }
  }
  if( addRowid ){
    u32 iKey;


    Integerify(p, p->tos-nField);
    iKey = intToKey(aStack[p->tos-nField].i);
    memcpy(&zNewKey[j], &iKey, sizeof(u32));
    sqliteVdbePopStack(p, nField+1);
    if( pOp->p2 && containsNull ) pc = pOp->p2 - 1;
  }else{
    if( pOp->p2==0 ) sqliteVdbePopStack(p, nField+addRowid);
  }
  p->tos++;
  aStack[p->tos].n = nByte;
  if( nByte<=NBFS ){
    assert( zNewKey==zTemp );
    aStack[p->tos].z = aStack[p->tos].zShort;
    memcpy(aStack[p->tos].z, zTemp, nByte);
    aStack[p->tos].flags = MEM_Str;
  }else{
    aStack[p->tos].flags = MEM_Str|MEM_Dyn;
    aStack[p->tos].z = zNewKey;

  }
  break;
}

/* Opcode: IncrKey * * *
**
** The top of the stack should contain an index key generated by
** The MakeKey opcode.  This routine increases the least significant
** byte of that key by one.  This is used so that the MoveTo opcode
** will move to the first entry greater than the key rather than to
** the key itself.
*/
case OP_IncrKey: {
  int tos = p->tos;

  VERIFY( if( tos<0 ) goto bad_instruction );
  Stringify(p, tos);
  if( aStack[tos].flags & (MEM_Static|MEM_Ephem) ){
    /* CANT HAPPEN.  The IncrKey opcode is only applied to keys
    ** generated by MakeKey or MakeIdxKey and the results of those
    ** operands are always dynamic strings.

    */
    goto abort_due_to_error;
  }

  aStack[tos].z[aStack[tos].n-1]++;
  break;
}

/* Opcode: Checkpoint P1 * *
**
** Begin a checkpoint.  A checkpoint is the beginning of a operation that
** is part of a larger transaction but which might need to be rolled back

    rc = sqliteBtreeBeginTrans(db->aDb[i].pBt);
    switch( rc ){
      case SQLITE_BUSY: {
        if( db->xBusyCallback==0 ){
          p->pc = pc;
          p->undoTransOnError = 1;
          p->rc = SQLITE_BUSY;

          return SQLITE_BUSY;
        }else if( (*db->xBusyCallback)(db->pBusyArg, "", busy++)==0 ){
          sqliteSetString(&p->zErrMsg, sqlite_error_string(rc), (char*)0);
          busy = 0;
        }
        break;
      }

** temporary tables.
**
** 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: {
  int i = ++p->tos;
  int aMeta[SQLITE_N_BTREE_META];
  assert( pOp->p2<SQLITE_N_BTREE_META );
  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( db->aDb[pOp->p1].pBt!=0 );
  rc = sqliteBtreeGetMeta(db->aDb[pOp->p1].pBt, aMeta);

  aStack[i].i = aMeta[1+pOp->p2];
  aStack[i].flags = MEM_Int;
  break;
}

/* Opcode: SetCookie P1 P2 *
**
** Write the top of the stack into cookie number P2 of database P1.
** P2==0 is the schema version.  P2==1 is the database format.
** P2==2 is the recommended pager cache size, and so forth.  P1==0 is
** the main database file and P1==1 is the database file used to store
** temporary tables.
**
** A transaction must be started before executing this opcode.
*/
case OP_SetCookie: {
  int aMeta[SQLITE_N_BTREE_META];
  assert( pOp->p2<SQLITE_N_BTREE_META );
  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( db->aDb[pOp->p1].pBt!=0 );
  VERIFY( if( p->tos<0 ) goto not_enough_stack; )
  Integerify(p, p->tos)
  rc = sqliteBtreeGetMeta(db->aDb[pOp->p1].pBt, aMeta);
  if( rc==SQLITE_OK ){
    aMeta[1+pOp->p2] = aStack[p->tos].i;
    rc = sqliteBtreeUpdateMeta(db->aDb[pOp->p1].pBt, aMeta);
  }

  POPSTACK;
  break;
}

/* Opcode: VerifyCookie P1 P2 *
**
** Check the value of global database parameter number 0 (the
** schema version) and make sure it is equal to P2.  

**
** See also OpenRead.
*/
case OP_OpenRead:
case OP_OpenWrite: {
  int busy = 0;
  int i = pOp->p1;
  int tos = p->tos;
  int p2 = pOp->p2;
  int wrFlag;
  Btree *pX;
  int iDb;
  
  VERIFY( if( tos<0 ) goto not_enough_stack; );
  Integerify(p, tos);
  iDb = p->aStack[tos].i;
  tos--;
  VERIFY( if( iDb<0 || iDb>=db->nDb ) goto bad_instruction; );
  VERIFY( if( db->aDb[iDb].pBt==0 ) goto bad_instruction; );
  pX = db->aDb[iDb].pBt;

  wrFlag = pOp->opcode==OP_OpenWrite;
  if( p2<=0 ){
    VERIFY( if( tos<0 ) goto not_enough_stack; );
    Integerify(p, tos);
    p2 = p->aStack[tos].i;
    POPSTACK;
    if( p2<2 ){
      sqliteSetString(&p->zErrMsg, "root page number less than 2", (char*)0);
      rc = SQLITE_INTERNAL;
      break;
    }
  }
  VERIFY( if( i<0 ) goto bad_instruction; )
  if( expandCursorArraySize(p, i) ) goto no_mem;
  sqliteVdbeCleanupCursor(&p->aCsr[i]);
  memset(&p->aCsr[i], 0, sizeof(Cursor));
  p->aCsr[i].nullRow = 1;
  if( pX==0 ) break;
  do{
    rc = sqliteBtreeCursor(pX, p2, wrFlag, &p->aCsr[i].pCursor);
    switch( rc ){
      case SQLITE_BUSY: {
        if( db->xBusyCallback==0 ){
          p->pc = pc;
          p->rc = SQLITE_BUSY;

          return SQLITE_BUSY;
        }else if( (*db->xBusyCallback)(db->pBusyArg, pOp->p3, ++busy)==0 ){
          sqliteSetString(&p->zErrMsg, sqlite_error_string(rc), (char*)0);
          busy = 0;
        }
        break;
      }
      case SQLITE_OK: {
        busy = 0;
        break;
      }
      default: {
        goto abort_due_to_error;
      }
    }
  }while( busy );
  if( p2<=0 ){
    POPSTACK;
  }
  POPSTACK;
  break;
}

/* Opcode: OpenTemp P1 P2 *
**
** Open a new cursor to a transient table.
** The transient cursor is always opened read/write even if 

** context of this opcode means for the duration of a single SQL statement
** whereas "Temporary" in the context of CREATE TABLE means for the duration
** of the connection to the database.  Same word; different meanings.
*/
case OP_OpenTemp: {
  int i = pOp->p1;
  Cursor *pCx;
  VERIFY( if( i<0 ) goto bad_instruction; )
  if( expandCursorArraySize(p, i) ) goto no_mem;
  pCx = &p->aCsr[i];
  sqliteVdbeCleanupCursor(pCx);
  memset(pCx, 0, sizeof(*pCx));
  pCx->nullRow = 1;
  rc = sqliteBtreeFactory(db, 0, 1, TEMP_PAGES, &pCx->pBt);

**
** A pseudo-table created by this opcode is useful for holding the
** NEW or OLD tables in a trigger.
*/
case OP_OpenPseudo: {
  int i = pOp->p1;
  Cursor *pCx;
  VERIFY( if( i<0 ) goto bad_instruction; )
  if( expandCursorArraySize(p, i) ) goto no_mem;
  pCx = &p->aCsr[i];
  sqliteVdbeCleanupCursor(pCx);
  memset(pCx, 0, sizeof(*pCx));
  pCx->nullRow = 1;
  pCx->pseudoTable = 1;
  break;

** is not zero then an immediate jump to P2 is made.
**
** See also: MoveTo
*/
case OP_MoveLt:
case OP_MoveTo: {
  int i = pOp->p1;
  int tos = p->tos;
  Cursor *pC;

  VERIFY( if( tos<0 ) goto not_enough_stack; )

  assert( i>=0 && i<p->nCursor );
  pC = &p->aCsr[i];
  if( pC->pCursor!=0 ){
    int res, oc;
    pC->nullRow = 0;
    if( aStack[tos].flags & MEM_Int ){
      int iKey = intToKey(aStack[tos].i);
      if( pOp->p2==0 && pOp->opcode==OP_MoveTo ){
        pC->movetoTarget = iKey;
        pC->deferredMoveto = 1;

        POPSTACK;
        break;
      }
      sqliteBtreeMoveto(pC->pCursor, (char*)&iKey, sizeof(int), &res);
      pC->lastRecno = aStack[tos].i;
      pC->recnoIsValid = res==0;
    }else{
      Stringify(p, tos);
      sqliteBtreeMoveto(pC->pCursor, aStack[tos].z, aStack[tos].n, &res);
      pC->recnoIsValid = 0;
    }
    pC->deferredMoveto = 0;
    sqlite_search_count++;
    oc = pOp->opcode;
    if( oc==OP_MoveTo && res<0 ){
      sqliteBtreeNext(pC->pCursor, &res);

        res = sqliteBtreeKeySize(pC->pCursor,&keysize)!=0 || keysize==0;
      }
      if( res && pOp->p2>0 ){
        pc = pOp->p2 - 1;
      }
    }
  }

  POPSTACK;
  break;
}

/* Opcode: Distinct P1 P2 *
**
** Use the top of the stack as a string key.  If a record with that key does
** not exist in the table of cursor P1, then jump to P2.  If the record

**
** See also: Distinct, Found, MoveTo, NotExists, IsUnique
*/
case OP_Distinct:
case OP_NotFound:
case OP_Found: {
  int i = pOp->p1;
  int tos = p->tos;
  int alreadyExists = 0;
  Cursor *pC;

  VERIFY( if( tos<0 ) goto not_enough_stack; )
  if( VERIFY( i>=0 && i<p->nCursor && ) (pC = &p->aCsr[i])->pCursor!=0 ){
    int res, rx;
    Stringify(p, tos);
    rx = sqliteBtreeMoveto(pC->pCursor, aStack[tos].z, aStack[tos].n, &res);
    alreadyExists = rx==SQLITE_OK && res==0;
    pC->deferredMoveto = 0;
  }
  if( pOp->opcode==OP_Found ){
    if( alreadyExists ) pc = pOp->p2 - 1;
  }else{
    if( !alreadyExists ) pc = pOp->p2 - 1;
  }
  if( pOp->opcode!=OP_Distinct ){

    POPSTACK;
  }
  break;
}

/* Opcode: IsUnique P1 P2 *
**
** The top of the stack is an integer record number.  Call this

** number for that entry is pushed onto the stack and control
** falls through to the next instruction.
**
** See also: Distinct, NotFound, NotExists, Found
*/
case OP_IsUnique: {
  int i = pOp->p1;
  int tos = p->tos;
  int nos = tos-1;
  BtCursor *pCrsr;
  int R;

  /* Pop the value R off the top of the stack
  */
  VERIFY( if( nos<0 ) goto not_enough_stack; )
  Integerify(p, tos);
  R = aStack[tos].i;   
  POPSTACK;

  if( VERIFY( i>=0 && i<p->nCursor && ) (pCrsr = p->aCsr[i].pCursor)!=0 ){
    int res, rc;
    int v;         /* The record number on the P1 entry that matches K */
    char *zKey;    /* The value of K */
    int nKey;      /* Number of bytes in K */

    /* Make sure K is a string and make zKey point to K
    */
    Stringify(p, nos);
    zKey = aStack[nos].z;
    nKey = aStack[nos].n;
    assert( nKey >= 4 );

    /* Search for an entry in P1 where all but the last four bytes match K.
    ** If there is no such entry, jump immediately to P2.
    */
    assert( p->aCsr[i].deferredMoveto==0 );
    rc = sqliteBtreeMoveto(pCrsr, zKey, nKey-4, &res);

    }

    /* The last four bytes of the key are different from R.  Convert the
    ** last four bytes of the key into an integer and push it onto the
    ** stack.  (These bytes are the record number of an entry that
    ** violates a UNIQUE constraint.)
    */
    p->tos++;
    aStack[tos].i = v;
    aStack[tos].flags = MEM_Int;
  }
  break;
}

/* Opcode: NotExists P1 P2 *
**
** Use the top of the stack as a integer key.  If a record with that key
** does not exist in table of P1, then jump to P2.  If the record
** does exist, then fall thru.  The cursor is left pointing to the
** record if it exists.  The integer key is popped from the stack.
**
** The difference between this operation and NotFound is that this
** operation assumes the key is an integer and NotFound assumes it
** is a string.
**
** See also: Distinct, Found, MoveTo, NotFound, IsUnique
*/
case OP_NotExists: {
  int i = pOp->p1;
  int tos = p->tos;
  BtCursor *pCrsr;

  VERIFY( if( tos<0 ) goto not_enough_stack; )
  if( VERIFY( i>=0 && i<p->nCursor && ) (pCrsr = p->aCsr[i].pCursor)!=0 ){
    int res, rx, iKey;
    assert( aStack[tos].flags & MEM_Int );
    iKey = intToKey(aStack[tos].i);
    rx = sqliteBtreeMoveto(pCrsr, (char*)&iKey, sizeof(int), &res);
    p->aCsr[i].lastRecno = aStack[tos].i;
    p->aCsr[i].recnoIsValid = res==0;
    p->aCsr[i].nullRow = 0;
    if( rx!=SQLITE_OK || res!=0 ){
      pc = pOp->p2 - 1;
      p->aCsr[i].recnoIsValid = 0;
    }
  }

  POPSTACK;
  break;
}

/* Opcode: NewRecno P1 * *
**
** Get a new integer record number used as the key to a table.
** The record number is not previously used as a key in the database
** table that cursor P1 points to.  The new record number is pushed 
** onto the stack.
*/
case OP_NewRecno: {
  int i = pOp->p1;
  int v = 0;
  Cursor *pC;

  if( VERIFY( i<0 || i>=p->nCursor || ) (pC = &p->aCsr[i])->pCursor==0 ){
    v = 0;
  }else{
    /* The next rowid or record number (different terms for the same
    ** thing) is obtained in a two-step algorithm.
    **
    ** First we attempt to find the largest existing rowid and add one
    ** to that.  But if the largest existing rowid is already the maximum

        rc = SQLITE_FULL;
        goto abort_due_to_error;
      }
    }
    pC->recnoIsValid = 0;
    pC->deferredMoveto = 0;
  }
  p->tos++;
  aStack[p->tos].i = v;
  aStack[p->tos].flags = MEM_Int;
  break;
}

/* Opcode: PutIntKey P1 P2 *
**
** Write an entry into the table of cursor P1.  A new entry is
** created if it doesn't already exist or the data for an existing

** stack.  The key is the next value down on the stack.  The key must
** be a string.  The stack is popped twice by this instruction.
**
** P1 may not be a pseudo-table opened using the OpenPseudo opcode.
*/
case OP_PutIntKey:
case OP_PutStrKey: {
  int tos = p->tos;
  int nos = p->tos-1;
  int i = pOp->p1;
  Cursor *pC;
  VERIFY( if( nos<0 ) goto not_enough_stack; )

  if( VERIFY( i>=0 && i<p->nCursor && )
      ((pC = &p->aCsr[i])->pCursor!=0 || pC->pseudoTable) ){
    char *zKey;
    int nKey, iKey;
    if( pOp->opcode==OP_PutStrKey ){
      Stringify(p, nos);
      nKey = aStack[nos].n;
      zKey = aStack[nos].z;
    }else{
      assert( aStack[nos].flags & MEM_Int );
      nKey = sizeof(int);
      iKey = intToKey(aStack[nos].i);
      zKey = (char*)&iKey;
      if( pOp->p2 ){
        db->nChange++;
        db->lastRowid = aStack[nos].i;
      }
      if( pC->nextRowidValid && aStack[nos].i>=pC->nextRowid ){
        pC->nextRowidValid = 0;
      }
    }
    if( pC->pseudoTable ){
      /* PutStrKey does not work for pseudo-tables.
      ** The following assert makes sure we are not trying to use
      ** PutStrKey on a pseudo-table
      */
      assert( pOp->opcode==OP_PutIntKey );
      sqliteFree(pC->pData);
      pC->iKey = iKey;
      pC->nData = aStack[tos].n;
      if( aStack[tos].flags & MEM_Dyn ){
        pC->pData = aStack[tos].z;
        aStack[tos].z = 0;
        aStack[tos].flags = MEM_Null;
      }else{
        pC->pData = sqliteMallocRaw( pC->nData );
        if( pC->pData ){
          memcpy(pC->pData, aStack[tos].z, pC->nData);
        }
      }
      pC->nullRow = 0;
    }else{
      rc = sqliteBtreeInsert(pC->pCursor, zKey, nKey,
                          aStack[tos].z, aStack[tos].n);
    }
    pC->recnoIsValid = 0;
    pC->deferredMoveto = 0;
  }
  POPSTACK;
  POPSTACK;
  break;
}

/* Opcode: Delete P1 P2 *
**
** Delete the record at which the P1 cursor is currently pointing.
**

**
** If the cursor is not pointing to a valid row, a NULL is pushed
** onto the stack.
*/
case OP_RowKey:
case OP_RowData: {
  int i = pOp->p1;
  int tos = ++p->tos;
  Cursor *pC;
  int n;


  assert( i>=0 && i<p->nCursor );
  pC = &p->aCsr[i];
  if( pC->nullRow ){
    aStack[tos].flags = MEM_Null;
  }else if( pC->pCursor!=0 ){
    BtCursor *pCrsr = pC->pCursor;
    sqliteVdbeCursorMoveto(pC);
    if( pC->nullRow ){
      aStack[tos].flags = MEM_Null;
      break;
    }else if( pC->keyAsData || pOp->opcode==OP_RowKey ){
      sqliteBtreeKeySize(pCrsr, &n);
    }else{
      sqliteBtreeDataSize(pCrsr, &n);
    }
    aStack[tos].n = n;
    if( n<=NBFS ){
      aStack[tos].flags = MEM_Str;
      aStack[tos].z = aStack[tos].zShort;
    }else{
      char *z = sqliteMallocRaw( n );
      if( z==0 ) goto no_mem;
      aStack[tos].flags = MEM_Str | MEM_Dyn;
      aStack[tos].z = z;
    }
    if( pC->keyAsData || pOp->opcode==OP_RowKey ){
      sqliteBtreeKey(pCrsr, 0, n, aStack[tos].z);
    }else{
      sqliteBtreeData(pCrsr, 0, n, aStack[tos].z);
    }
  }else if( pC->pseudoTable ){
    aStack[tos].n = pC->nData;
    aStack[tos].z = pC->pData;
    aStack[tos].flags = MEM_Str|MEM_Ephem;
  }else{
    aStack[tos].flags = MEM_Null;
  }
  break;
}

/* Opcode: Column P1 P2 *
**
** Interpret the data that cursor P1 points to as

** value pushed is always just a pointer into the record which is
** stored further down on the stack.  The column value is not copied.
*/
case OP_Column: {
  int amt, offset, end, payloadSize;
  int i = pOp->p1;
  int p2 = pOp->p2;
  int tos = p->tos+1;
  Cursor *pC;
  char *zRec;
  BtCursor *pCrsr;
  int idxWidth;
  unsigned char aHdr[10];

  assert( i<p->nCursor );

  if( i<0 ){
    VERIFY( if( tos+i<0 ) goto bad_instruction; )

    VERIFY( if( (aStack[tos+i].flags & MEM_Str)==0 ) goto bad_instruction; )
    zRec = aStack[tos+i].z;
    payloadSize = aStack[tos+i].n;
  }else if( (pC = &p->aCsr[i])->pCursor!=0 ){
    sqliteVdbeCursorMoveto(pC);
    zRec = 0;
    pCrsr = pC->pCursor;
    if( pC->nullRow ){
      payloadSize = 0;
    }else if( pC->keyAsData ){

    payloadSize = 0;
  }

  /* Figure out how many bytes in the column data and where the column
  ** data begins.
  */
  if( payloadSize==0 ){
    aStack[tos].flags = MEM_Null;
    p->tos = tos;
    break;
  }else if( payloadSize<256 ){
    idxWidth = 1;
  }else if( payloadSize<65536 ){
    idxWidth = 2;
  }else{
    idxWidth = 3;

    rc = SQLITE_CORRUPT;
    goto abort_due_to_error;
  }

  /* amt and offset now hold the offset to the start of data and the
  ** amount of data.  Go get the data and put it on the stack.
  */

  if( amt==0 ){
    aStack[tos].flags = MEM_Null;
  }else if( zRec ){
    aStack[tos].flags = MEM_Str | MEM_Ephem;
    aStack[tos].n = amt;
    aStack[tos].z = &zRec[offset];
  }else{
    if( amt<=NBFS ){
      aStack[tos].flags = MEM_Str;
      aStack[tos].z = aStack[tos].zShort;
      aStack[tos].n = amt;
    }else{
      char *z = sqliteMallocRaw( amt );
      if( z==0 ) goto no_mem;
      aStack[tos].flags = MEM_Str | MEM_Dyn;
      aStack[tos].z = z;
      aStack[tos].n = amt;
    }
    if( pC->keyAsData ){
      sqliteBtreeKey(pCrsr, offset, amt, aStack[tos].z);
    }else{
      sqliteBtreeData(pCrsr, offset, amt, aStack[tos].z);
    }
  }
  p->tos = tos;
  break;
}

/* Opcode: Recno P1 * *
**
** Push onto the stack an integer which is the first 4 bytes of the
** the key to the current entry in a sequential scan of the database
** file P1.  The sequential scan should have been started using the 
** Next opcode.
*/
case OP_Recno: {
  int i = pOp->p1;
  int tos = ++p->tos;
  Cursor *pC;
  int v;

  assert( i>=0 && i<p->nCursor );
  pC = &p->aCsr[i];
  sqliteVdbeCursorMoveto(pC);

  if( pC->recnoIsValid ){
    v = pC->lastRecno;
  }else if( pC->pseudoTable ){
    v = keyToInt(pC->iKey);
  }else if( pC->nullRow || pC->pCursor==0 ){
    aStack[tos].flags = MEM_Null;
    break;
  }else{
    assert( pC->pCursor!=0 );
    sqliteBtreeKey(pC->pCursor, 0, sizeof(u32), (char*)&v);
    v = keyToInt(v);
  }
  aStack[tos].i = v;
  aStack[tos].flags = MEM_Int;
  break;
}

/* Opcode: FullKey P1 * *
**
** Extract the complete key from the record that cursor P1 is currently
** pointing to and push the key onto the stack as a string.
**
** Compare this opcode to Recno.  The Recno opcode extracts the first
** 4 bytes of the key and pushes those bytes onto the stack as an
** integer.  This instruction pushes the entire key as a string.
**
** This opcode may not be used on a pseudo-table.
*/
case OP_FullKey: {
  int i = pOp->p1;
  int tos = ++p->tos;
  BtCursor *pCrsr;

  VERIFY( if( !p->aCsr[i].keyAsData ) goto bad_instruction; )
  VERIFY( if( p->aCsr[i].pseudoTable ) goto bad_instruction; )


  if( VERIFY( i>=0 && i<p->nCursor && ) (pCrsr = p->aCsr[i].pCursor)!=0 ){
    int amt;
    char *z;

    sqliteVdbeCursorMoveto(&p->aCsr[i]);
    sqliteBtreeKeySize(pCrsr, &amt);
    if( amt<=0 ){
      rc = SQLITE_CORRUPT;
      goto abort_due_to_error;
    }
    if( amt>NBFS ){
      z = sqliteMallocRaw( amt );
      if( z==0 ) goto no_mem;
      aStack[tos].flags = MEM_Str | MEM_Dyn;
    }else{
      z = aStack[tos].zShort;
      aStack[tos].flags = MEM_Str;
    }
    sqliteBtreeKey(pCrsr, 0, amt, z);
    aStack[tos].z = z;
    aStack[tos].n = amt;
  }
  break;
}

/* Opcode: NullRow P1 * *
**
** Move the cursor P1 to a null row.  Any OP_Column operations

** If P2==1, then the key must be unique.  If the key is not unique,
** the program aborts with a SQLITE_CONSTRAINT error and the database
** is rolled back.  If P3 is not null, then it becomes part of the
** error message returned with the SQLITE_CONSTRAINT.
*/
case OP_IdxPut: {
  int i = pOp->p1;
  int tos = p->tos;
  BtCursor *pCrsr;

  VERIFY( if( tos<0 ) goto not_enough_stack; )

  if( VERIFY( i>=0 && i<p->nCursor && ) (pCrsr = p->aCsr[i].pCursor)!=0 ){
    int nKey = aStack[tos].n;
    const char *zKey = aStack[tos].z;
    if( pOp->p2 ){
      int res, n;
      assert( aStack[tos].n >= 4 );
      rc = sqliteBtreeMoveto(pCrsr, zKey, nKey-4, &res);
      if( rc!=SQLITE_OK ) goto abort_due_to_error;
      while( res!=0 ){
        int c;
        sqliteBtreeKeySize(pCrsr, &n);
        if( n==nKey
           && sqliteBtreeKeyCompare(pCrsr, zKey, nKey-4, 4, &c)==SQLITE_OK

          break;
        }
      }
    }
    rc = sqliteBtreeInsert(pCrsr, zKey, nKey, "", 0);
    assert( p->aCsr[i].deferredMoveto==0 );
  }

  POPSTACK;
  break;
}

/* Opcode: IdxDelete P1 * *
**
** The top of the stack is an index key built using the MakeIdxKey opcode.
** This opcode removes that entry from the index.
*/
case OP_IdxDelete: {
  int i = pOp->p1;
  int tos = p->tos;
  BtCursor *pCrsr;

  VERIFY( if( tos<0 ) goto not_enough_stack; )

  if( VERIFY( i>=0 && i<p->nCursor && ) (pCrsr = p->aCsr[i].pCursor)!=0 ){
    int rx, res;
    rx = sqliteBtreeMoveto(pCrsr, aStack[tos].z, aStack[tos].n, &res);
    if( rx==SQLITE_OK && res==0 ){
      rc = sqliteBtreeDelete(pCrsr);
    }
    assert( p->aCsr[i].deferredMoveto==0 );
  }

  POPSTACK;
  break;
}

/* Opcode: IdxRecno P1 * *
**
** Push onto the stack an integer which is the last 4 bytes of the
** the key to the current entry in index P1.  These 4 bytes should
** be the record number of the table entry to which this index entry
** points.
**
** See also: Recno, MakeIdxKey.
*/
case OP_IdxRecno: {
  int i = pOp->p1;
  int tos = ++p->tos;
  BtCursor *pCrsr;



  if( VERIFY( i>=0 && i<p->nCursor && ) (pCrsr = p->aCsr[i].pCursor)!=0 ){
    int v;
    int sz;
    assert( p->aCsr[i].deferredMoveto==0 );
    sqliteBtreeKeySize(pCrsr, &sz);
    if( sz<sizeof(u32) ){
      aStack[tos].flags = MEM_Null;
    }else{
      sqliteBtreeKey(pCrsr, sz - sizeof(u32), sizeof(u32), (char*)&v);
      v = keyToInt(v);
      aStack[tos].i = v;
      aStack[tos].flags = MEM_Int;
    }


  }
  break;
}

/* Opcode: IdxGT P1 P2 *
**
** Compare the top of the stack against the key on the index entry that

** then jump to P2.  Otherwise fall through to the next instruction.
** In either case, the stack is popped once.
*/
case OP_IdxLT:
case OP_IdxGT:
case OP_IdxGE: {
  int i= pOp->p1;
  int tos = p->tos;
  BtCursor *pCrsr;



  if( VERIFY( i>=0 && i<p->nCursor && ) (pCrsr = p->aCsr[i].pCursor)!=0 ){
    int res, rc;
 
    Stringify(p, tos);
    assert( p->aCsr[i].deferredMoveto==0 );
    rc = sqliteBtreeKeyCompare(pCrsr, aStack[tos].z, aStack[tos].n, 4, &res);
    if( rc!=SQLITE_OK ){
      break;
    }
    if( pOp->opcode==OP_IdxLT ){
      res = -res;
    }else if( pOp->opcode==OP_IdxGE ){
      res++;
    }
    if( res>0 ){
      pc = pOp->p2 - 1 ;
    }
  }

  POPSTACK;
  break;
}

/* Opcode: IdxIsNull P1 P2 *
**
** The top of the stack contains an index entry such as might be generated
** by the MakeIdxKey opcode.  This routine looks at the first P1 fields of
** that key.  If any of the first P1 fields are NULL, then a jump is made
** to address P2.  Otherwise we fall straight through.
**
** The index entry is always popped from the stack.
*/
case OP_IdxIsNull: {
  int i = pOp->p1;
  int tos = p->tos;
  int k, n;
  const char *z;

  assert( tos>=0 );
  assert( aStack[tos].flags & MEM_Str );
  z = aStack[tos].z;
  n = aStack[tos].n;
  for(k=0; k<n && i>0; i--){
    if( z[k]=='a' ){
      pc = pOp->p2-1;
      break;
    }
    while( k<n && z[k] ){ k++; }
    k++;
  }

  POPSTACK;
  break;
}

/* Opcode: Destroy P1 P2 *
**
** Delete an entire database table or index whose root page in the database
** file is given by P1.

** auxiliary database file if P2==1.  Push the page number of the
** root page of the new index onto the stack.
**
** See documentation on OP_CreateTable for additional information.
*/
case OP_CreateIndex:
case OP_CreateTable: {
  int i = ++p->tos;
  int pgno;
  assert( pOp->p3!=0 && pOp->p3type==P3_POINTER );
  assert( pOp->p2>=0 && pOp->p2<db->nDb );
  assert( db->aDb[pOp->p2].pBt!=0 );
  if( pOp->opcode==OP_CreateTable ){
    rc = sqliteBtreeCreateTable(db->aDb[pOp->p2].pBt, &pgno);
  }else{
    rc = sqliteBtreeCreateIndex(db->aDb[pOp->p2].pBt, &pgno);
  }

  if( rc==SQLITE_OK ){
    aStack[i].i = pgno;
    aStack[i].flags = MEM_Int;
    *(u32*)pOp->p3 = pgno;
    pOp->p3 = 0;
  }
  break;
}

/* Opcode: IntegrityCk P1 P2 *

** file, not the main database file.
**
** This opcode is used for testing purposes only.
*/
case OP_IntegrityCk: {
  int nRoot;
  int *aRoot;
  int tos = ++p->tos;
  int iSet = pOp->p1;
  Set *pSet;
  int j;
  HashElem *i;
  char *z;

  VERIFY( if( iSet<0 || iSet>=p->nSet ) goto bad_instruction; )

  pSet = &p->aSet[iSet];
  nRoot = sqliteHashCount(&pSet->hash);
  aRoot = sqliteMallocRaw( sizeof(int)*(nRoot+1) );
  if( aRoot==0 ) goto no_mem;
  for(j=0, i=sqliteHashFirst(&pSet->hash); i; i=sqliteHashNext(i), j++){
    toInt((char*)sqliteHashKey(i), &aRoot[j]);
  }
  aRoot[j] = 0;
  sqliteHashClear(&pSet->hash);
  pSet->prev = 0;
  z = sqliteBtreeIntegrityCheck(db->aDb[pOp->p2].pBt, aRoot, nRoot);
  if( z==0 || z[0]==0 ){
    if( z ) sqliteFree(z);
    aStack[tos].z = "ok";
    aStack[tos].n = 3;
    aStack[tos].flags = MEM_Str | MEM_Static;
  }else{
    aStack[tos].z = z;
    aStack[tos].n = strlen(z) + 1;
    aStack[tos].flags = MEM_Str | MEM_Dyn;
  }
  sqliteFree(aRoot);
  break;
}

/* Opcode: ListWrite * * *
**
** Write the integer on the top of the stack
** into the temporary storage list.
*/
case OP_ListWrite: {
  Keylist *pKeylist;
  VERIFY( if( p->tos<0 ) goto not_enough_stack; )
  pKeylist = p->pList;
  if( pKeylist==0 || pKeylist->nUsed>=pKeylist->nKey ){
    pKeylist = sqliteMallocRaw( sizeof(Keylist)+999*sizeof(pKeylist->aKey[0]) );
    if( pKeylist==0 ) goto no_mem;
    pKeylist->nKey = 1000;
    pKeylist->nRead = 0;
    pKeylist->nUsed = 0;
    pKeylist->pNext = p->pList;
    p->pList = pKeylist;
  }
  Integerify(p, p->tos);
  pKeylist->aKey[pKeylist->nUsed++] = aStack[p->tos].i;

  POPSTACK;
  break;
}

/* Opcode: ListRewind * * *
**
** Rewind the temporary buffer back to the beginning.  This is 
** now a no-op.

** push nothing but instead jump to P2.
*/
case OP_ListRead: {
  Keylist *pKeylist;
  CHECK_FOR_INTERRUPT;
  pKeylist = p->pList;
  if( pKeylist!=0 ){
    VERIFY(
      if( pKeylist->nRead<0 
        || pKeylist->nRead>=pKeylist->nUsed
        || pKeylist->nRead>=pKeylist->nKey ) goto bad_instruction;
    )
    p->tos++;
    aStack[p->tos].i = pKeylist->aKey[pKeylist->nRead++];
    aStack[p->tos].flags = MEM_Int;
    aStack[p->tos].z = 0;
    if( pKeylist->nRead>=pKeylist->nUsed ){
      p->pList = pKeylist->pNext;
      sqliteFree(pKeylist);
    }
  }else{
    pc = pOp->p2 - 1;
  }

/* Opcode: SortPut * * *
**
** The TOS is the key and the NOS is the data.  Pop both from the stack
** and put them on the sorter.  The key and data should have been
** made using SortMakeKey and SortMakeRec, respectively.
*/
case OP_SortPut: {
  int tos = p->tos;
  int nos = tos - 1;
  Sorter *pSorter;
  VERIFY( if( tos<1 ) goto not_enough_stack; )

  if( Dynamicify(p, tos) || Dynamicify(p, nos) ) goto no_mem;
  pSorter = sqliteMallocRaw( sizeof(Sorter) );
  if( pSorter==0 ) goto no_mem;
  pSorter->pNext = p->pSort;
  p->pSort = pSorter;
  assert( aStack[tos].flags & MEM_Dyn );
  pSorter->nKey = aStack[tos].n;
  pSorter->zKey = aStack[tos].z;

  pSorter->nData = aStack[nos].n;
  if( aStack[nos].flags & MEM_Dyn ){
    pSorter->pData = aStack[nos].z;
  }else{
    pSorter->pData = sqliteStrDup(aStack[nos].z);
  }
  aStack[tos].flags = 0;
  aStack[nos].flags = 0;
  aStack[tos].z = 0;
  aStack[nos].z = 0;
  p->tos -= 2;
  break;
}

/* Opcode: SortMakeRec P1 * *
**
** The top P1 elements are the arguments to a callback.  Form these
** elements into a single data entry that can be stored on a sorter
** using SortPut and later fed to a callback using SortCallback.
*/
case OP_SortMakeRec: {
  char *z;
  char **azArg;
  int nByte;
  int nField;
  int i, j;


  nField = pOp->p1;
  VERIFY( if( p->tos+1<nField ) goto not_enough_stack; )

  nByte = 0;
  for(i=p->tos-nField+1; i<=p->tos; i++){
    if( (aStack[i].flags & MEM_Null)==0 ){
      Stringify(p, i);
      nByte += aStack[i].n;
    }
  }
  nByte += sizeof(char*)*(nField+1);
  azArg = sqliteMallocRaw( nByte );
  if( azArg==0 ) goto no_mem;
  z = (char*)&azArg[nField+1];
  for(j=0, i=p->tos-nField+1; i<=p->tos; i++, j++){
    if( aStack[i].flags & MEM_Null ){
      azArg[j] = 0;
    }else{
      azArg[j] = z;
      strcpy(z, aStack[i].z);
      z += aStack[i].n;
    }
  }
  sqliteVdbePopStack(p, nField);
  p->tos++;
  aStack[p->tos].n = nByte;
  aStack[p->tos].z = (char*)azArg;
  aStack[p->tos].flags = MEM_Str|MEM_Dyn;
  break;
}

/* Opcode: SortMakeKey * * P3
**
** Convert the top few entries of the stack into a sort key.  The
** number of stack entries consumed is the number of characters in 

** See also the MakeKey and MakeIdxKey opcodes.
*/
case OP_SortMakeKey: {
  char *zNewKey;
  int nByte;
  int nField;
  int i, j, k;


  nField = strlen(pOp->p3);
  VERIFY( if( p->tos+1<nField ) goto not_enough_stack; )
  nByte = 1;
  for(i=p->tos-nField+1; i<=p->tos; i++){
    if( (aStack[i].flags & MEM_Null)!=0 ){
      nByte += 2;
    }else{
      Stringify(p, i);
      nByte += aStack[i].n+2;
    }
  }
  zNewKey = sqliteMallocRaw( nByte );
  if( zNewKey==0 ) goto no_mem;
  j = 0;
  k = 0;
  for(i=p->tos-nField+1; i<=p->tos; i++){
    if( (aStack[i].flags & MEM_Null)!=0 ){
      zNewKey[j++] = 'N';
      zNewKey[j++] = 0;
      k++;
    }else{
      zNewKey[j++] = pOp->p3[k++];
      memcpy(&zNewKey[j], aStack[i].z, aStack[i].n-1);
      j += aStack[i].n-1;
      zNewKey[j++] = 0;
    }
  }
  zNewKey[j] = 0;
  assert( j<nByte );
  sqliteVdbePopStack(p, nField);
  p->tos++;
  aStack[p->tos].n = nByte;
  aStack[p->tos].flags = MEM_Str|MEM_Dyn;
  aStack[p->tos].z = zNewKey;
  break;
}

/* Opcode: Sort * * *
**
** Sort all elements on the sorter.  The algorithm is a
** mergesort.

** to instruction P2.
*/
case OP_SortNext: {
  Sorter *pSorter = p->pSort;
  CHECK_FOR_INTERRUPT;
  if( pSorter!=0 ){
    p->pSort = pSorter->pNext;
    p->tos++;
    aStack[p->tos].z = pSorter->pData;
    aStack[p->tos].n = pSorter->nData;
    aStack[p->tos].flags = MEM_Str|MEM_Dyn;
    sqliteFree(pSorter->zKey);
    sqliteFree(pSorter);
  }else{
    pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: SortCallback P1 * *
**
** The top of the stack contains a callback record built using
** the SortMakeRec operation with the same P1 value as this
** instruction.  Pop this record from the stack and invoke the
** callback on it.
*/
case OP_SortCallback: {
  int i = p->tos;
  VERIFY( if( i<0 ) goto not_enough_stack; )
  if( p->xCallback==0 ){
    p->pc = pc+1;
    p->azResColumn = (char**)aStack[i].z;
    p->nResColumn = pOp->p1;
    p->popStack = 1;

    return SQLITE_ROW;
  }else{
    if( sqliteSafetyOff(db) ) goto abort_due_to_misuse;
    if( p->xCallback(p->pCbArg, pOp->p1, (char**)aStack[i].z, p->azColName)!=0){
      rc = SQLITE_ABORT;
    }
    if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
    p->nCallback++;
  }

  POPSTACK;
  if( sqlite_malloc_failed ) goto no_mem;
  break;
}

/* Opcode: SortReset * * *
**
** Remove any elements that remain on the sorter.
*/
case OP_SortReset: {
  sqliteVdbeSorterReset(p);
  break;
}

/* Opcode: FileOpen * * P3
**
** Open the file named by P3 for reading using the FileRead opcode.
** If P3 is "stdin" then open standard input for reading.
*/
case OP_FileOpen: {
  VERIFY( if( pOp->p3==0 ) goto bad_instruction; )
  if( p->pFile ){
    if( p->pFile!=stdin ) fclose(p->pFile);
    p->pFile = 0;
  }
  if( sqliteStrICmp(pOp->p3,"stdin")==0 ){
    p->pFile = stdin;
  }else{

**
** Push onto the stack the P1-th column of the most recently read line
** from the input file.
*/
case OP_FileColumn: {
  int i = pOp->p1;
  char *z;
  if( VERIFY( i>=0 && i<p->nField && ) p->azField ){

    z = p->azField[i];
  }else{
    z = 0;
  }
  p->tos++;
  if( z ){
    aStack[p->tos].n = strlen(z) + 1;
    aStack[p->tos].z = z;
    aStack[p->tos].flags = MEM_Str;
  }else{
    aStack[p->tos].n = 0;
    aStack[p->tos].z = 0;
    aStack[p->tos].flags = MEM_Null;
  }
  break;
}

/* Opcode: MemStore P1 P2 *
**
** Write the top of the stack into memory location P1.
** P1 should be a small integer since space is allocated
** for all memory locations between 0 and P1 inclusive.
**
** After the data is stored in the memory location, the
** stack is popped once if P2 is 1.  If P2 is zero, then
** the original data remains on the stack.
*/
case OP_MemStore: {
  int i = pOp->p1;
  int tos = p->tos;
  char *zOld;
  Mem *pMem;
  int flags;
  VERIFY( if( tos<0 ) goto not_enough_stack; )
  if( i>=p->nMem ){
    int nOld = p->nMem;
    Mem *aMem;
    p->nMem = i + 5;
    aMem = sqliteRealloc(p->aMem, p->nMem*sizeof(p->aMem[0]));
    if( aMem==0 ) goto no_mem;
    if( aMem!=p->aMem ){
      int j;
      for(j=0; j<nOld; j++){
        if( aMem[j].z==p->aMem[j].zShort ){
          aMem[j].z = aMem[j].zShort;
        }
      }
    }
    p->aMem = aMem;
    if( nOld<p->nMem ){
      memset(&p->aMem[nOld], 0, sizeof(p->aMem[0])*(p->nMem-nOld));
    }
  }
  pMem = &p->aMem[i];
  flags = pMem->flags;
  if( flags & MEM_Dyn ){
    zOld = pMem->z;
  }else{
    zOld = 0;
  }
  *pMem = aStack[tos];
  flags = pMem->flags;
  if( flags & (MEM_Static|MEM_Dyn|MEM_Ephem) ){
    if( (flags & MEM_Static)!=0 || (pOp->p2 && (flags & MEM_Dyn)!=0) ){
      /* pMem->z = zStack[tos]; *** do nothing */
    }else if( flags & MEM_Str ){

      pMem->z = sqliteMallocRaw( pMem->n );
      if( pMem->z==0 ) goto no_mem;
      memcpy(pMem->z, aStack[tos].z, pMem->n);
      pMem->flags |= MEM_Dyn;
      pMem->flags &= ~(MEM_Static|MEM_Ephem);
    }
  }else{
    pMem->z = pMem->zShort;
  }
  if( zOld ) sqliteFree(zOld);
  if( pOp->p2 ){
    aStack[tos].z = 0;
    aStack[tos].flags = 0;
    POPSTACK;
  }
  break;
}

/* Opcode: MemLoad P1 * *
**
** Push a copy of the value in memory location P1 onto the stack.
**
** If the value is a string, then the value pushed is a pointer to
** the string that is stored in the memory location.  If the memory
** location is subsequently changed (using OP_MemStore) then the
** value pushed onto the stack will change too.
*/
case OP_MemLoad: {
  int tos = ++p->tos;
  int i = pOp->p1;
  VERIFY( if( i<0 || i>=p->nMem ) goto bad_instruction; )

  memcpy(&aStack[tos], &p->aMem[i], sizeof(aStack[tos])-NBFS);;
  if( aStack[tos].flags & MEM_Str ){
    /* aStack[tos].z = p->aMem[i].z; */
    aStack[tos].flags |= MEM_Ephem;
    aStack[tos].flags &= ~(MEM_Dyn|MEM_Static);
  }
  break;
}

/* Opcode: MemIncr P1 P2 *
**
** Increment the integer valued memory cell P1 by 1.  If P2 is not zero
** and the result after the increment is greater than zero, then jump
** to P2.
**
** This instruction throws an error if the memory cell is not initially
** an integer.
*/
case OP_MemIncr: {
  int i = pOp->p1;
  Mem *pMem;
  VERIFY( if( i<0 || i>=p->nMem ) goto bad_instruction; )
  pMem = &p->aMem[i];
  VERIFY( if( pMem->flags != MEM_Int ) goto bad_instruction; )
  pMem->i++;
  if( pOp->p2>0 && pMem->i>0 ){
     pc = pOp->p2 - 1;
  }
  break;
}

**
** Initialize the function parameters for an aggregate function.
** The aggregate will operate out of aggregate column P2.
** P3 is a pointer to the FuncDef structure for the function.
*/
case OP_AggInit: {
  int i = pOp->p2;
  VERIFY( if( i<0 || i>=p->agg.nMem ) goto bad_instruction; )
  p->agg.apFunc[i] = (FuncDef*)pOp->p3;
  break;
}

/* Opcode: AggFunc * P2 P3
**
** Execute the step function for an aggregate.  The
** function has P2 arguments.  P3 is a pointer to the FuncDef
** structure that specifies the function.
**
** The top of the stack must be an integer which is the index of
** the aggregate column that corresponds to this aggregate function.
** Ideally, this index would be another parameter, but there are
** no free parameters left.  The integer is popped from the stack.
*/
case OP_AggFunc: {
  int n = pOp->p2;
  int i;
  Mem *pMem;

  sqlite_func ctx;

  VERIFY( if( n<0 ) goto bad_instruction; )
  VERIFY( if( p->tos+1<n ) goto not_enough_stack; )
  VERIFY( if( aStack[p->tos].flags!=MEM_Int ) goto bad_instruction; )


  for(i=p->tos-n; i<p->tos; i++){
    if( aStack[i].flags & MEM_Null ){
      aStack[i].z = 0;
    }else{
      Stringify(p, i);

    }
    p->zArgv[i] = aStack[i].z;
  }
  i = aStack[p->tos].i;
  VERIFY( if( i<0 || i>=p->agg.nMem ) goto bad_instruction; )
  ctx.pFunc = (FuncDef*)pOp->p3;
  pMem = &p->agg.pCurrent->aMem[i];
  ctx.s.z = pMem->zShort;  /* Space used for small aggregate contexts */
  ctx.pAgg = pMem->z;
  ctx.cnt = ++pMem->i;
  ctx.isError = 0;
  ctx.isStep = 1;
  (ctx.pFunc->xStep)(&ctx, n, (const char**)&p->zArgv[p->tos-n]);
  pMem->z = ctx.pAgg;
  pMem->flags = MEM_AggCtx;
  sqliteVdbePopStack(p, n+1);
  if( ctx.isError ){
    rc = SQLITE_ERROR;
  }
  break;
}

/* Opcode: AggFocus * P2 *

** The order of aggregator opcodes is important.  The order is:
** AggReset AggFocus AggNext.  In other words, you must execute
** AggReset first, then zero or more AggFocus operations, then
** zero or more AggNext operations.  You must not execute an AggFocus
** in between an AggNext and an AggReset.
*/
case OP_AggFocus: {
  int tos = p->tos;
  AggElem *pElem;
  char *zKey;
  int nKey;

  VERIFY( if( tos<0 ) goto not_enough_stack; )
  Stringify(p, tos);
  zKey = aStack[tos].z; 
  nKey = aStack[tos].n;
  pElem = sqliteHashFind(&p->agg.hash, zKey, nKey);
  if( pElem ){
    p->agg.pCurrent = pElem;
    pc = pOp->p2 - 1;
  }else{
    AggInsert(&p->agg, zKey, nKey);
    if( sqlite_malloc_failed ) goto no_mem;
  }

  POPSTACK;
  break; 
}

/* Opcode: AggSet * P2 *
**
** Move the top of the stack into the P2-th field of the current
** aggregate.  String values are duplicated into new memory.
*/
case OP_AggSet: {
  AggElem *pFocus = AggInFocus(p->agg);
  int i = pOp->p2;
  int tos = p->tos;
  VERIFY( if( tos<0 ) goto not_enough_stack; )
  if( pFocus==0 ) goto no_mem;


  if( VERIFY( i>=0 && ) i<p->agg.nMem ){
    Mem *pMem = &pFocus->aMem[i];
    char *zOld;
    if( pMem->flags & MEM_Dyn ){
      zOld = pMem->z;
    }else{
      zOld = 0;
    }
    Deephemeralize(p, tos);
    *pMem = aStack[tos];
    if( pMem->flags & MEM_Dyn ){
      aStack[tos].z = 0;
      aStack[tos].flags = 0;
    }else if( pMem->flags & (MEM_Static|MEM_AggCtx) ){
      /* pMem->z = zStack[tos]; *** do nothing */
    }else if( pMem->flags & MEM_Str ){
      pMem->z = pMem->zShort;
    }
    if( zOld ) sqliteFree(zOld);
  }

  POPSTACK;
  break;
}

/* Opcode: AggGet * P2 *
**
** Push a new entry onto the stack which is a copy of the P2-th field
** of the current aggregate.  Strings are not duplicated so
** string values will be ephemeral.
*/
case OP_AggGet: {
  AggElem *pFocus = AggInFocus(p->agg);
  int i = pOp->p2;
  int tos = ++p->tos;
  if( pFocus==0 ) goto no_mem;



  if( VERIFY( i>=0 && ) i<p->agg.nMem ){
    Mem *pMem = &pFocus->aMem[i];
    aStack[tos] = *pMem;
    aStack[tos].flags &= ~MEM_Dyn;
    aStack[tos].flags |= MEM_Ephem;
  }
  break;
}

/* Opcode: AggNext * P2 *
**
** Make the next aggregate value the current aggregate.  The prior

      ctx.isStep = 0;
      ctx.pFunc = p->agg.apFunc[i];
      (*p->agg.apFunc[i]->xFinalize)(&ctx);
      if( freeCtx ){
        sqliteFree( aMem[i].z );
      }
      aMem[i] = ctx.s;
      if( (aMem[i].flags & MEM_Str) &&
              (aMem[i].flags & (MEM_Dyn|MEM_Static|MEM_Ephem))==0 ){
        aMem[i].z = aMem[i].zShort;
      }
    }
  }
  break;
}

      sqliteHashInit(&p->aSet[k].hash, SQLITE_HASH_BINARY, 1);
    }
    p->nSet = i+1;
  }
  if( pOp->p3 ){
    sqliteHashInsert(&p->aSet[i].hash, pOp->p3, strlen(pOp->p3)+1, p);
  }else{
    int tos = p->tos;
    if( tos<0 ) goto not_enough_stack;
    Stringify(p, tos);
    sqliteHashInsert(&p->aSet[i].hash, aStack[tos].z, aStack[tos].n, p);

    POPSTACK;
  }
  if( sqlite_malloc_failed ) goto no_mem;
  break;
}

/* Opcode: SetFound P1 P2 *
**
** Pop the stack once and compare the value popped off with the
** contents of set P1.  If the element popped exists in set P1,
** then jump to P2.  Otherwise fall through.
*/
case OP_SetFound: {
  int i = pOp->p1;
  int tos = p->tos;
  VERIFY( if( tos<0 ) goto not_enough_stack; )
  Stringify(p, tos);
  if( i>=0 && i<p->nSet &&
       sqliteHashFind(&p->aSet[i].hash, aStack[tos].z, aStack[tos].n)){
    pc = pOp->p2 - 1;
  }

  POPSTACK;
  break;
}

/* Opcode: SetNotFound P1 P2 *
**
** Pop the stack once and compare the value popped off with the
** contents of set P1.  If the element popped does not exists in 
** set P1, then jump to P2.  Otherwise fall through.
*/
case OP_SetNotFound: {
  int i = pOp->p1;
  int tos = p->tos;
  VERIFY( if( tos<0 ) goto not_enough_stack; )
  Stringify(p, tos);
  if( i<0 || i>=p->nSet ||
       sqliteHashFind(&p->aSet[i].hash, aStack[tos].z, aStack[tos].n)==0 ){
    pc = pOp->p2 - 1;
  }

  POPSTACK;
  break;
}

/* Opcode: SetFirst P1 P2 *
**
** Read the first element from set P1 and push it onto the stack.  If the
** set is empty, push nothing and jump immediately to P2.  This opcode is
** used in combination with OP_SetNext to loop over all elements of a set.
*/
/* Opcode: SetNext P1 P2 *
**
** Read the next element from set P1 and push it onto the stack.  If there
** are no more elements in the set, do not do the push and fall through.
** Otherwise, jump to P2 after pushing the next set element.
*/
case OP_SetFirst: 
case OP_SetNext: {
  Set *pSet;
  int tos;
  CHECK_FOR_INTERRUPT;
  if( pOp->p1<0 || pOp->p1>=p->nSet ){
    if( pOp->opcode==OP_SetFirst ) pc = pOp->p2 - 1;
    break;
  }
  pSet = &p->aSet[pOp->p1];
  if( pOp->opcode==OP_SetFirst ){
    pSet->prev = sqliteHashFirst(&pSet->hash);
    if( pSet->prev==0 ){
      pc = pOp->p2 - 1;
      break;
    }
  }else{
    VERIFY( if( pSet->prev==0 ) goto bad_instruction; )
    pSet->prev = sqliteHashNext(pSet->prev);
    if( pSet->prev==0 ){
      break;
    }else{
      pc = pOp->p2 - 1;
    }
  }
  tos = ++p->tos;
  aStack[tos].z = sqliteHashKey(pSet->prev);
  aStack[tos].n = sqliteHashKeysize(pSet->prev);
  aStack[tos].flags = MEM_Str | MEM_Ephem;
  break;
}

/* Opcode: Vacuum * * *
**
** Vacuum the entire database.  This opcode will cause other virtual
** machines to be created and run.  It may not be called from within

    ** the evaluator loop.  So we can leave it out when NDEBUG is defined.
    */
#ifndef NDEBUG
    if( pc<-1 || pc>=p->nOp ){
      sqliteSetString(&p->zErrMsg, "jump destination out of range", (char*)0);
      rc = SQLITE_INTERNAL;
    }
    if( p->trace && p->tos>=0 ){
      int i;
      fprintf(p->trace, "Stack:");
      for(i=p->tos; i>=0 && i>p->tos-5; i--){
        if( aStack[i].flags & MEM_Null ){
          fprintf(p->trace, " NULL");
        }else if( (aStack[i].flags & (MEM_Int|MEM_Str))==(MEM_Int|MEM_Str) ){
          fprintf(p->trace, " si:%d", aStack[i].i);
        }else if( aStack[i].flags & MEM_Int ){
          fprintf(p->trace, " i:%d", aStack[i].i);
        }else if( aStack[i].flags & MEM_Real ){
          fprintf(p->trace, " r:%g", aStack[i].r);
        }else if( aStack[i].flags & MEM_Str ){
          int j, k;
          char zBuf[100];
          zBuf[0] = ' ';
          if( aStack[i].flags & MEM_Dyn ){
            zBuf[1] = 'z';
            assert( (aStack[i].flags & (MEM_Static|MEM_Ephem))==0 );
          }else if( aStack[i].flags & MEM_Static ){
            zBuf[1] = 't';
            assert( (aStack[i].flags & (MEM_Dyn|MEM_Ephem))==0 );
          }else if( aStack[i].flags & MEM_Ephem ){
            zBuf[1] = 'e';
            assert( (aStack[i].flags & (MEM_Static|MEM_Dyn))==0 );
          }else{
            zBuf[1] = 's';
          }
          zBuf[2] = '[';
          k = 3;
          for(j=0; j<20 && j<aStack[i].n; j++){
            int c = aStack[i].z[j];
            if( c==0 && j==aStack[i].n-1 ) break;
            if( isprint(c) && !isspace(c) ){
              zBuf[k++] = c;
            }else{
              zBuf[k++] = '.';
            }
          }
          zBuf[k++] = ']';

  if( rc ){
    p->rc = rc;
    rc = SQLITE_ERROR;
  }else{
    rc = SQLITE_DONE;
  }
  p->magic = VDBE_MAGIC_HALT;

  return rc;

  /* Jump to here if a malloc() fails.  It's hard to get a malloc()
  ** to fail on a modern VM computer, so this code is untested.
  */
no_mem:
  sqliteSetString(&p->zErrMsg, "out of memory", (char*)0);

  if( db->magic!=SQLITE_MAGIC_BUSY ){
    rc = SQLITE_MISUSE;
  }else{
    rc = SQLITE_INTERRUPT;
  }
  sqliteSetString(&p->zErrMsg, sqlite_error_string(rc), (char*)0);
  goto vdbe_halt;

  /* Jump to here if a operator is encountered that requires more stack
  ** operands than are currently available on the stack.
  */
not_enough_stack:
  sqlite_snprintf(sizeof(zBuf),zBuf,"%d",pc);
  sqliteSetString(&p->zErrMsg, "too few operands on stack at ", zBuf, (char*)0);
  rc = SQLITE_INTERNAL;
  goto vdbe_halt;

  /* Jump here if an illegal or illformed instruction is executed.
  */
VERIFY(
bad_instruction:
  sqlite_snprintf(sizeof(zBuf),zBuf,"%d",pc);
  sqliteSetString(&p->zErrMsg, "illegal operation at ", zBuf, (char*)0);
  rc = SQLITE_INTERNAL;
  goto vdbe_halt;
)
}

#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_Dyn       0x0010   /* Need to call sqliteFree() on Mem.z */
#define MEM_Static    0x0020   /* Mem.z points to a static string */
#define MEM_Ephem     0x0040   /* Mem.z points to an ephemeral string */


/* 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    0x0040   /* Mem.z points to an agg function context */

/*
** 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,

  FILE *trace;        /* Write an execution trace here, if not NULL */
  int nOp;            /* Number of instructions in the program */
  int nOpAlloc;       /* Number of slots allocated for aOp[] */
  Op *aOp;            /* Space to hold the virtual machine's program */
  int nLabel;         /* Number of labels used */
  int nLabelAlloc;    /* Number of slots allocated in aLabel[] */
  int *aLabel;        /* Space to hold the labels */
  int tos;            /* Index of top of stack */
  Mem *aStack;        /* The operand stack, except string values */

  char **zArgv;       /* Text values used by the callback */
  char **azColName;   /* Becomes the 4th parameter to callbacks */
  int nCursor;        /* Number of slots in aCsr[] */
  Cursor *aCsr;       /* One element of this array for each open cursor */
  Sorter *pSort;      /* A linked list of objects to be sorted */
  FILE *pFile;        /* At most one open file handler */
  int nField;         /* Number of file fields */

** 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 */
#define VDBE_MAGIC_HALT     0x519c2973    /* VDBE has completed execution */
#define VDBE_MAGIC_DEAD     0xb606c3c8    /* The VDBE has been deallocated */

/*
** Here is a macro to handle the common case of popping the stack
** once.  This macro only works from within the sqliteVdbeExec()
** function.
*/
#define POPSTACK \
  assert(p->tos>=0); \
  if( aStack[p->tos].flags & MEM_Dyn ) sqliteFree(aStack[p->tos].z); \
  p->tos--;

/*
** Function prototypes
*/
void sqliteVdbeCleanupCursor(Cursor*);
void sqliteVdbeSorterReset(Vdbe*);
void sqliteVdbeAggReset(Agg*);
void sqliteVdbeKeylistFree(Keylist*);
void sqliteVdbePopStack(Vdbe*,int);
int sqliteVdbeCursorMoveto(Cursor*);
int sqliteVdbeByteSwap(int);
#if !defined(NDEBUG) || defined(VDBE_PROFILE)
void sqliteVdbePrintOp(FILE*, int, Op*);
#endif

    p->s.z = 0;
    p->s.n = 0;
  }else{
    if( n<0 ) n = strlen(zResult);
    if( n<NBFS-1 ){
      memcpy(p->s.zShort, zResult, n);
      p->s.zShort[n] = 0;
      p->s.flags = MEM_Str;
      p->s.z = p->s.zShort;
    }else{
      p->s.z = sqliteMallocRaw( n+1 );
      if( p->s.z ){
        memcpy(p->s.z, zResult, n);
        p->s.z[n] = 0;
      }

  ** Allocation all the stack space we will ever need.
  */
  if( p->aStack==0 ){
    p->nVar = nVar;
    assert( nVar>=0 );
    n = isExplain ? 10 : p->nOp;
    p->aStack = sqliteMalloc(
    n*(sizeof(p->aStack[0]) + 2*sizeof(char*))     /* aStack and zArgv */
      + p->nVar*(sizeof(char*)+sizeof(int)+1)      /* azVar, anVar, abVar */
    );
    p->zArgv = (char**)&p->aStack[n];
    p->azColName = (char**)&p->zArgv[n];
    p->azVar = (char**)&p->azColName[n];
    p->anVar = (int*)&p->azVar[p->nVar];
    p->abVar = (u8*)&p->anVar[p->nVar];
  }

  sqliteHashInit(&p->agg.hash, SQLITE_HASH_BINARY, 0);
  p->agg.pSearch = 0;
#ifdef MEMORY_DEBUG
  if( sqliteOsFileExists("vdbe_trace") ){
    p->trace = stdout;
  }
#endif
  p->tos = -1;
  p->pc = 0;
  p->rc = SQLITE_OK;
  p->uniqueCnt = 0;
  p->returnDepth = 0;
  p->errorAction = OE_Abort;
  p->undoTransOnError = 0;
  p->xCallback = xCallback;

    p->pSort = pSorter->pNext;
    sqliteFree(pSorter->zKey);
    sqliteFree(pSorter->pData);
    sqliteFree(pSorter);
  }
}

/*
** Pop the stack N times.  Free any memory associated with the
** popped stack elements.
*/
void sqliteVdbePopStack(Vdbe *p, int N){
  assert( N>=0 );
  if( p->aStack==0 ) return;
  while( N-- > 0 ){
    if( p->aStack[p->tos].flags & MEM_Dyn ){
      sqliteFree(p->aStack[p->tos].z);
    }
    p->aStack[p->tos].flags = 0;
    p->tos--;
  }
}

/*
** Reset an Agg structure.  Delete all its contents. 
**
** For installable aggregate functions, if the step function has been
** called, make sure the finalizer function has also been called.  The
** finalizer might need to free memory that was allocated as part of its
** private context.  If the finalizer has not been called yet, call it

**
** This routine will automatically close any cursors, lists, and/or
** sorters that were left open.  It also deletes the values of
** variables in the azVariable[] array.
*/
static void Cleanup(Vdbe *p){
  int i;




  sqliteVdbePopStack(p, p->tos+1);





  closeAllCursors(p);
  if( p->aMem ){
    for(i=0; i<p->nMem; i++){
      if( p->aMem[i].flags & MEM_Dyn ){
        sqliteFree(p->aMem[i].z);
      }
    }

  }
  for(i=0; i<db->nDb; i++){
    if( db->aDb[i].pBt && db->aDb[i].inTrans==2 ){
      sqliteBtreeCommitCkpt(db->aDb[i].pBt);
      db->aDb[i].inTrans = 1;
    }
  }
  assert( p->tos<p->pc || sqlite_malloc_failed==1 );
#ifdef VDBE_PROFILE
  {
    FILE *out = fopen("vdbe_profile.out", "a");
    if( out ){
      int i;
      fprintf(out, "---- ");
      for(i=0; i<p->nOp; i++){

#
# This script looks for memory leaks by analyzing the output of "sqlite" 
# when compiled with the MEMORY_DEBUG=2 option.
#
/[0-9]+ malloc / {
  mem[$6] = $0
}
/[0-9]+ realloc / {
  mem[$8] = "";
  mem[$10] = $0
}
/[0-9]+ free / {



  mem[$6] = "";
  str[$6] = ""
}
/^string at / {
  addr = $4
  sub("string at " addr " is ","")
  str[addr] = $0