SQLite

**
** Various scripts scan this source file in order to generate HTML
** 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 1.188 2003/01/01 23:06:21 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The makefile scans this source file and creates the following
** array of string constants which are the names of all VDBE opcodes.

      break;
    }
  }
  zBuf[i]  = 0;
  return i>0 ? zBuf : 0;
}

#if !defined(NDEBUG) || defined(VDBE_PROFILE)
/*
** Print a single opcode.  This routine is used for debugging only.
*/
static void vdbePrintOp(FILE *pOut, int pc, Op *pOp){
  char *zP3;
  char zPtr[40];
  if( pOp->p3type==P3_POINTER ){

    if( aCsr==0 ) return 1;
    p->aCsr = aCsr;
    memset(&p->aCsr[p->nCursor], 0, sizeof(Cursor)*(mxCursor+1-p->nCursor));
    p->nCursor = mxCursor+1;
  }
  return 0;
}

#ifdef VDBE_PROFILE
/*
** The following routine only works on pentium-class processors.
** It uses the RDTSC opcode to read cycle count value out of the
** processor and returns that value.  This can be used for high-res
** profiling.
*/
__inline__ unsigned long long int hwtime(void){
  unsigned long long int x;
  __asm__("rdtsc\n\t"
          "mov %%edx, %%ecx\n\t"
          :"=A" (x));
  return x;
}
#endif

/*
** Execute the program in the VDBE.
**
** If an error occurs, an error message is written to memory obtained
** from sqliteMalloc() and *pzErrMsg is made to point to that memory.
** The return parameter is the number of errors.

  unsigned uniqueCnt = 0;     /* Used by OP_MakeRecord when P2!=0 */
  int errorAction = OE_Abort; /* Recovery action to do in case of an error */
  int undoTransOnError = 0;   /* If error, either ROLLBACK or COMMIT */
  int inTempTrans = 0;        /* True if temp database is transactioned */
  char zBuf[100];             /* Space to sprintf() an integer */
  int returnStack[100];     /* Return address stack for OP_Gosub & OP_Return */
  int returnDepth = 0;      /* Next unused element in returnStack[] */
#ifdef VDBE_PROFILE
  unsigned long long start;
#endif


  /* No instruction ever pushes more than a single element onto the
  ** stack.  And the stack never grows on successive executions of the
  ** same loop.  So the total number of instructions is an upper bound
  ** on the maximum stack depth required.
  **
  ** Allocation all the stack space we will ever need.
  */
  NeedStack(p, p->nOp);
  zStack = p->zStack;
  aStack = p->aStack;
  p->tos = -1;
#ifdef VDBE_PROFILE
  {
    int i;
    for(i=0; i<p->nOp; i++){
      p->aOp[i].cnt = 0;
      p->aOp[i].cycles = 0;
    }
  }
#endif

  /* Initialize the aggregrate hash table.
  */
  sqliteHashInit(&p->agg.hash, SQLITE_HASH_BINARY, 0);
  p->agg.pSearch = 0;

  rc = SQLITE_OK;
#ifdef MEMORY_DEBUG
  if( access("vdbe_trace",0)==0 ){
    p->trace = stdout;
  }
#endif
  if( sqlite_malloc_failed ) goto no_mem;
  for(pc=0; !sqlite_malloc_failed && rc==SQLITE_OK && pc<p->nOp
             VERIFY(&& pc>=0); pc++){
#ifdef VDBE_PROFILE
    start = hwtime();
#endif
    pOp = &p->aOp[pc];

    /* Interrupt processing if requested.
    */
    if( db->flags & SQLITE_Interrupt ){
      db->flags &= ~SQLITE_Interrupt;
      if( db->magic!=SQLITE_MAGIC_BUSY ){

** table or index.  If there is no previous key/value pairs then fall through
** to the following instruction.  But if the cursor backup was successful,
** jump immediately to P2.
*/
case OP_Prev:
case OP_Next: {
  int i = pOp->p1;
  Cursor *pC;
  BtCursor *pCrsr;

  if( VERIFY( i>=0 && i<p->nCursor && ) 
      (pCrsr = (pC = &p->aCsr[i])->pCursor)!=0 ){
    int res;
    if( pC->nullRow ){
      res = 1;
    }else{
      rc = pOp->opcode==OP_Next ? sqliteBtreeNext(pCrsr, &res) :
                                  sqliteBtreePrevious(pCrsr, &res);
      pC->nullRow = res;
    }
    if( res==0 ){
      pc = pOp->p2 - 1;
      sqlite_search_count++;
    }
    pC->recnoIsValid = 0;
  }
  break;
}

/* Opcode: IdxPut P1 P2 P3
**
** The top of the stack hold an SQL index key made using the

/*****************************************************************************
** The cases of the switch statement above this line should all be indented
** by 6 spaces.  But the left-most 6 spaces have been removed to improve the
** readability.  From this point on down, the normal indentation rules are
** restored.
*****************************************************************************/
    }

#ifdef VDBE_PROFILE
    pOp->cycles += hwtime() - start;
    pOp->cnt++;
#endif

    /* The following code adds nothing to the actual functionality
    ** of the program.  It is only here for testing and debugging.
    ** On the other hand, it does burn CPU cycles every time through
    ** the evaluator loop.  So we can leave it out when NDEBUG is defined.
    */
#ifndef NDEBUG

      }
    }
    sqliteRollbackInternalChanges(db);
  }
  sqliteBtreeCommitCkpt(pBt);
  if( db->pBeTemp ) sqliteBtreeCommitCkpt(db->pBeTemp);
  assert( p->tos<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++){
        fprintf(out, "%02x", p->aOp[i].opcode);
      }
      fprintf(out, "\n");
      for(i=0; i<p->nOp; i++){
        fprintf(out, "%6d %10lld %8lld ",
           p->aOp[i].cnt,
           p->aOp[i].cycles,
           p->aOp[i].cnt>0 ? p->aOp[i].cycles/p->aOp[i].cnt : 0
        );
        vdbePrintOp(out, i, &p->aOp[i]);
      }
      fclose(out);
    }
  }
#endif
  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(pzErrMsg, "out of memory", 0);

*************************************************************************
** 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 1.61 2003/01/01 23:06:21 drh Exp $
*/
#ifndef _SQLITE_VDBE_H_
#define _SQLITE_VDBE_H_
#include <stdio.h>

/*
** A single VDBE is an opaque structure named "Vdbe".  Only routines

*/
struct VdbeOp {
  int 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;

/*
** Allowed values of VdbeOp.p3type
*/
#define P3_NOTUSED    0   /* The P3 parameter is not used */