** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.35 2001/10/22 02:58:09 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.
................................................................................
** Note that apCell[] contains enough space to hold up to two more Cells
** than can possibly fit on one page.  In the steady state, every apCell[]
** points to memory inside u.aDisk[].  But in the middle of an insert
** operation, some apCell[] entries may temporarily point to data space
** outside of u.aDisk[].  This is a transient situation that is quickly
** resolved.  But while it is happening, it is possible for a database
** page to hold as many as two more cells than it might otherwise hold.
** The extra too entries in apCell[] are an allowance for this situation.
**
** The pParent field points back to the parent page.  This allows us to
** walk up the BTree from any leaf to the root.  Care must be taken to
** unref() the parent page pointer when this page is no longer referenced.
** The pageDestructor() routine handles that chore.
*/
struct MemPage {

** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.36 2001/11/01 13:52:53 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.
................................................................................
** Note that apCell[] contains enough space to hold up to two more Cells
** than can possibly fit on one page.  In the steady state, every apCell[]
** points to memory inside u.aDisk[].  But in the middle of an insert
** operation, some apCell[] entries may temporarily point to data space
** outside of u.aDisk[].  This is a transient situation that is quickly
** resolved.  But while it is happening, it is possible for a database
** page to hold as many as two more cells than it might otherwise hold.
** The extra two entries in apCell[] are an allowance for this situation.
**
** The pParent field points back to the parent page.  This allows us to
** walk up the BTree from any leaf to the root.  Care must be taken to
** unref() the parent page pointer when this page is no longer referenced.
** The pageDestructor() routine handles that chore.
*/
struct MemPage {

** type to the other occurs as necessary.
** 
** Most of the code in this file is taken up by the sqliteVdbeExec()
** function which does the work of interpreting a VDBE program.
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.89 2001/10/22 02:58:10 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** SQL is translated into a sequence of instructions to be
** executed by a virtual machine.  Each instruction is an instance
................................................................................
  Integerify(p, tos);
  Release(p, tos);
  aStack[tos].i = !aStack[tos].i;
  aStack[tos].flags = STK_Int;
  break;
}

/* Opcode:  * * *
**
** Interpret the top of the stack as an value.  Replace it
** with its ones-complement.
*/
case OP_BitNot: {
  int tos = p->tos;
  VERIFY( if( p->tos<0 ) goto not_enough_stack; )

** type to the other occurs as necessary.
** 
** Most of the code in this file is taken up by the sqliteVdbeExec()
** function which does the work of interpreting a VDBE program.
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.90 2001/11/01 13:52:54 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** SQL is translated into a sequence of instructions to be
** executed by a virtual machine.  Each instruction is an instance
................................................................................
  Integerify(p, tos);
  Release(p, tos);
  aStack[tos].i = !aStack[tos].i;
  aStack[tos].flags = STK_Int;
  break;
}

/* Opcode: BitNot * * *
**
** Interpret the top of the stack as an value.  Replace it
** with its ones-complement.
*/
case OP_BitNot: {
  int tos = p->tos;
  VERIFY( if( p->tos<0 ) goto not_enough_stack; )