/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** 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.
**
*************************************************************************
** Header file for the Virtual DataBase Engine (VDBE)
**
** This header defines the interface to the virtual database engine
** or VDBE.  The VDBE implements an abstract machine that runs a
** simple program to access and modify the underlying database.
**
** $Id: vdbe.h,v 1.71 2004/02/22 20:05:02 drh Exp $
*/
#ifndef _SQLITE_VDBE_H_
#define _SQLITE_VDBE_H_
#include <stdio.h>

/*
** A single VDBE is an opaque structure named "Vdbe".  Only routines
** in the source file sqliteVdbe.c are allowed to see the insides
** of this structure.
*/
typedef struct Vdbe Vdbe;

/*
** A single instruction of the virtual machine has an opcode
** and as many as three operands.  The instruction is recorded
** as an instance of the following structure:
*/
struct VdbeOp {
  u8 opcode;          /* What operation to perform */
  int p1;             /* First operand */
  int p2;             /* Second parameter (often the jump destination) */
  char *p3;           /* Third parameter */
  int p3type;         /* P3_STATIC, P3_DYNAMIC or P3_POINTER */
#ifdef VDBE_PROFILE
  int cnt;            /* Number of times this instruction was executed */
  long long cycles;   /* Total time spend executing this instruction */
#endif
};
typedef struct VdbeOp VdbeOp;

/*
** A smaller version of VdbeOp used for the VdbeAddOpList() function because
** it takes up less space.
*/
struct VdbeOpList {
  u8 opcode;          /* What operation to perform */
  signed char p1;     /* First operand */
  short int p2;       /* Second parameter (often the jump destination) */
  char *p3;           /* Third parameter */
};
typedef struct VdbeOpList VdbeOpList;

/*
** Allowed values of VdbeOp.p3type
*/
#define P3_NOTUSED    0   /* The P3 parameter is not used */
#define P3_DYNAMIC  (-1)  /* Pointer to a string obtained from sqliteMalloc() */
#define P3_STATIC   (-2)  /* Pointer to a static string */
#define P3_POINTER  (-3)  /* P3 is a pointer to some structure or object */

/*
** The following macro converts a relative address in the p2 field
** of a VdbeOp structure into a negative number so that 
** sqliteVdbeAddOpList() knows that the address is relative.  Calling
** the macro again restores the address.
*/
#define ADDR(X)  (-1-(X))

/*
** The makefile scans the vdbe.c source file and creates the "opcodes.h"
** header file that defines a number for each opcode used by the VDBE.
*/
#include "opcodes.h"

/*
** Prototypes for the VDBE interface.  See comments on the implementation
** for a description of what each of these routines does.
*/
Vdbe *sqliteVdbeCreate(sqlite*);
void sqliteVdbeCreateCallback(Vdbe*, int*);
int sqliteVdbeAddOp(Vdbe*,int,int,int);
int sqliteVdbeOp3(Vdbe*,int,int,int,const char *zP3,int);
int sqliteVdbeCode(Vdbe*,...);
int sqliteVdbeAddOpList(Vdbe*, int nOp, VdbeOpList const *aOp);
void sqliteVdbeChangeP1(Vdbe*, int addr, int P1);
void sqliteVdbeChangeP2(Vdbe*, int addr, int P2);
void sqliteVdbeChangeP3(Vdbe*, int addr, const char *zP1, int N);
void sqliteVdbeDequoteP3(Vdbe*, int addr);
int sqliteVdbeFindOp(Vdbe*, int, int);
VdbeOp *sqliteVdbeGetOp(Vdbe*, int);
int sqliteVdbeMakeLabel(Vdbe*);
void sqliteVdbeDelete(Vdbe*);
void sqliteVdbeMakeReady(Vdbe*,int,int);
int sqliteVdbeExec(Vdbe*);
int sqliteVdbeList(Vdbe*);
int sqliteVdbeFinalize(Vdbe*,char**);
void sqliteVdbeResolveLabel(Vdbe*, int);
int sqliteVdbeCurrentAddr(Vdbe*);
void sqliteVdbeTrace(Vdbe*,FILE*);
void sqliteVdbeCompressSpace(Vdbe*,int);
int sqliteVdbeReset(Vdbe*,char **);
int sqliteVdbeSetVariables(Vdbe*,int,const char**);

#endif
