SQLite

/*
** A pointer to an instance of this structure is passed as the user-context
** pointer when registering for an unlock-notify callback.
*/
typedef struct UnlockNotification UnlockNotification;
struct UnlockNotification {
  int fired;                           /* True after unlock event has occured */
  pthread_cond_t cond;                 /* Condition variable to wait on */
  pthread_mutex_t mutex;               /* Mutex to protect structure */
};

/*
** This function is an unlock-notify callback registered with SQLite.
*/
static void unlock_notify_cb(void **apArg, int nArg){
  int i;

  REGISTER_TRACE(pOp->p1, pIn1);
  pc = pcDest;
  break;
}

/* Opcode:  HaltIfNull  P1 P2 P3 P4 *
**
** Check the value in register P3.  If is is NULL then Halt using
** parameter P1, P2, and P4 as if this were a Halt instruction.  If the
** value in register P3 is not NULL, then this routine is a no-op.
*/
case OP_HaltIfNull: {      /* in3 */
  pIn3 = &aMem[pOp->p3];
  if( (pIn3->flags & MEM_Null)==0 ) break;
  /* Fall through into OP_Halt */

** This works just like the Lt opcode except that the jump is taken if
** the operands in registers P1 and P3 are not equal.  See the Lt opcode for
** additional information.
**
** If SQLITE_NULLEQ is set in P5 then the result of comparison is always either
** true or false and is never NULL.  If both operands are NULL then the result
** of comparison is false.  If either operand is NULL then the result is true.
** If neither operand is NULL the the result is the same as it would be if
** the SQLITE_NULLEQ flag were omitted from P5.
*/
/* Opcode: Eq P1 P2 P3 P4 P5
**
** This works just like the Lt opcode except that the jump is taken if
** the operands in registers P1 and P3 are equal.
** See the Lt opcode for additional information.
**
** If SQLITE_NULLEQ is set in P5 then the result of comparison is always either
** true or false and is never NULL.  If both operands are NULL then the result
** of comparison is true.  If either operand is NULL then the result is false.
** If neither operand is NULL the the result is the same as it would be if
** the SQLITE_NULLEQ flag were omitted from P5.
*/
/* Opcode: Le P1 P2 P3 P4 P5
**
** This works just like the Lt opcode except that the jump is taken if
** the content of register P3 is less than or equal to the content of
** register P1.  See the Lt opcode for additional information.

    sqlite3VdbeMemSetInt64(pOut, ~sqlite3VdbeIntValue(pIn1));
  }
  break;
}

/* Opcode: If P1 P2 P3 * *
**
** Jump to P2 if the value in register P1 is true.  The value is
** is considered true if it is numeric and non-zero.  If the value
** in P1 is NULL then take the jump if P3 is true.
*/
/* Opcode: IfNot P1 P2 P3 * *
**
** Jump to P2 if the value in register P1 is False.  The value is
** is considered true if it has a numeric value of zero.  If the value
** in P1 is NULL then take the jump if P3 is true.
*/
case OP_If:                 /* jump, in1 */
case OP_IfNot: {            /* jump, in1 */
  int c;
  pIn1 = &aMem[pOp->p1];

    }
  }
  break;
}

/* Opcode: NotExists P1 P2 P3 * *
**
** Use the content of register P3 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 through.  The cursor is left 
** pointing to the record if it exists.
**
** The difference between this operation and NotFound is that this
** operation assumes the key is an integer and that P1 is a table whereas
** NotFound assumes key is a blob constructed from MakeRecord and

** The record number is not previously used as a key in the database
** table that cursor P1 points to.  The new record number is written
** written to register P2.
**
** If P3>0 then P3 is a register in the root frame of this VDBE that holds 
** the largest previously 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 */
  i64 v;                 /* The new rowid */
  VdbeCursor *pC;        /* Cursor of table to get the new rowid */
  int res;               /* Result of an sqlite3BtreeLast() */

  }
  pC->rowidIsValid = 0;
  break;
}

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