SQLite

  int pc=0;                  /* The program counter */
  Op *aOp = p->aOp;          /* Copy of p->aOp */
  Op *pOp;                   /* Current operation */
  int rc = SQLITE_OK;        /* Value to return */
  sqlite3 *db = p->db;       /* The database */
  u8 resetSchemaOnFault = 0; /* Reset schema after an error if positive */
  u8 encoding = ENC(db);     /* The database encoding */
  int iCompare = 0;          /* Result of last OP_Compare operation */
  unsigned nVmStep = 0;      /* Number of virtual machine steps */
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK

  unsigned nProgressOps = 0; /* nVmStep at last progress callback. */
#endif


  Mem *aMem = p->aMem;       /* Copy of p->aMem */
  Mem *pIn1 = 0;             /* 1st input operand */
  Mem *pIn2 = 0;             /* 2nd input operand */
  Mem *pIn3 = 0;             /* 3rd input operand */
  Mem *pOut = 0;             /* Output operand */
  int *aPermute = 0;         /* Permutation of columns for OP_Compare */
  i64 lastRowid = db->lastRowid;  /* Saved value of the last insert ROWID */

  assert( p->bIsReader || p->readOnly!=0 );
  p->rc = SQLITE_OK;
  assert( p->explain==0 );
  p->pResultSet = 0;
  db->busyHandler.nBusy = 0;
  CHECK_FOR_INTERRUPT;
  sqlite3VdbeIOTraceSql(p);



#ifdef SQLITE_DEBUG
  sqlite3BeginBenignMalloc();
  if( p->pc==0  && (p->db->flags & SQLITE_VdbeListing)!=0 ){
    int i;
    printf("VDBE Program Listing:\n");
    sqlite3VdbePrintSql(p);
    for(i=0; i<p->nOp; i++){

#ifdef SQLITE_TEST
    if( sqlite3_interrupt_count>0 ){
      sqlite3_interrupt_count--;
      if( sqlite3_interrupt_count==0 ){
        sqlite3_interrupt(db);
      }
    }





















#endif

    /* On any opcode with the "out2-prerelease" tag, free any
    ** external allocations out of mem[p2] and set mem[p2] to be
    ** an undefined integer.  Opcodes will either fill in the integer
    ** value or convert mem[p2] to a different type.
    */

**
** An unconditional jump to address P2.
** The next instruction executed will be 
** the one at index P2 from the beginning of
** the program.
*/
case OP_Goto: {             /* jump */
  pc = pOp->p2 - 1;

  /* Opcodes that are used as the bottom of a loop (OP_Next, OP_Prev,
  ** OP_VNext, OP_RowSetNext, or OP_SorterNext) all jump here upon
  ** completion.  Check to see if sqlite3_interrupt() has been called
  ** or if the progress callback needs to be invoked. 
  **
  ** This code uses unstructured "goto" statements and does not look clean.
  ** But that is not due to sloppy coding habits. The code is written this
  ** way for performance, to avoid having to run the interrupt and progress
  ** checks on every opcode.  This helps sqlite3_step() to run about 1.5%
  ** faster according to "valgrind --tool=cachegrind" */
check_for_interrupt:
  CHECK_FOR_INTERRUPT;
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  /* Call the progress callback if it is configured and the required number
  ** of VDBE ops have been executed (either since this invocation of
  ** sqlite3VdbeExec() or since last time the progress callback was called).
  ** If the progress callback returns non-zero, exit the virtual machine with
  ** a return code SQLITE_ABORT.
  */
  if( db->xProgress!=0 && (nVmStep - nProgressOps)>=db->nProgressOps ){
    int prc;
    prc = db->xProgress(db->pProgressArg);
    if( prc!=0 ){
      rc = SQLITE_INTERRUPT;
      goto vdbe_error_halt;
    }
    nProgressOps = nVmStep;
  }
#endif
  
  break;
}

/* Opcode:  Gosub P1 P2 * * *
**
** Write the current address onto register P1
** and then jump to address P2.

*/
case OP_SorterNext:    /* jump */
case OP_Prev:          /* jump */
case OP_Next: {        /* jump */
  VdbeCursor *pC;
  int res;


  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  assert( pOp->p5<=ArraySize(p->aCounter) );
  pC = p->apCsr[pOp->p1];
  if( pC==0 ){
    break;  /* See ticket #2273 */
  }
  assert( pC->isSorter==(pOp->opcode==OP_SorterNext) );

    pc = pOp->p2 - 1;
    if( pOp->p5 ) p->aCounter[pOp->p5-1]++;
#ifdef SQLITE_TEST
    sqlite3_search_count++;
#endif
  }
  pC->rowidIsValid = 0;
  goto check_for_interrupt;
}

/* Opcode: IdxInsert P1 P2 P3 * P5
**
** Register P2 holds an SQL index key made using the
** MakeRecord instructions.  This opcode writes that key
** into the index P1.  Data for the entry is nil.

**
** Extract the smallest value from boolean index P1 and put that value into
** register P3.  Or, if boolean index P1 is initially empty, leave P3
** unchanged and jump to instruction P2.
*/
case OP_RowSetRead: {       /* jump, in1, out3 */
  i64 val;

  pIn1 = &aMem[pOp->p1];
  if( (pIn1->flags & MEM_RowSet)==0 
   || sqlite3RowSetNext(pIn1->u.pRowSet, &val)==0
  ){
    /* The boolean index is empty */
    sqlite3VdbeMemSetNull(pIn1);
    pc = pOp->p2 - 1;
  }else{
    /* A value was pulled from the index */
    sqlite3VdbeMemSetInt64(&aMem[pOp->p3], val);
  }
  goto check_for_interrupt;
}

/* Opcode: RowSetTest P1 P2 P3 P4
**
** Register P3 is assumed to hold a 64-bit integer value. If register P1
** contains a RowSet object and that RowSet object contains
** the value held in P3, jump to register P2. Otherwise, insert the

    res = pModule->xEof(pCur->pVtabCursor);
  }

  if( !res ){
    /* If there is data, jump to P2 */
    pc = pOp->p2 - 1;
  }
  goto check_for_interrupt;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VRename P1 * * P4 *
**
** P4 is a pointer to a virtual table object, an sqlite3_vtab structure.

    INSERT INTO abc VALUES(4, 5, 6);
    INSERT INTO abc VALUES(7, 8, 9);
  }

  set ::res [list]
  db eval {SELECT a, b, c FROM abc} {
    lappend ::res $a $b $c
    db progress 5 "expr 1"
    catch {db eval {SELECT a, b, c FROM abc} { }} msg
    lappend ::res $msg
  }

  set ::res
} {1 2 3 interrupted 4 5 6 interrupted 7 8 9 interrupted}