SQLite

         case 1:   sqlite3SelectTrace = *ptr;      break;
         case 2:   *ptr = sqlite3WhereTrace;       break;
         case 3:   sqlite3WhereTrace = *ptr;       break;
       }
       break;
    }

#ifdef SQLITE_DEBUG
#if defined(SQLITE_DEBUG) && !defined(SQLITE_OMIT_WSD)
    /* sqlite3_test_control(SQLITE_TESTCTRL_TUNE, id, *piValue)
    **
    ** If "id" is an integer between 1 and SQLITE_NTUNE then set the value
    ** of the id-th tuning parameter to *piValue.  If "id" is between -1
    ** and -SQLITE_NTUNE, then write the current value of the (-id)-th
    ** tuning parameter into *piValue.
    **

  /* Register all VFSes defined in the aVfs[] array */
  for(i=0; i<(sizeof(aVfs)/sizeof(sqlite3_vfs)); i++){
    sqlite3_vfs_register(&aVfs[i], i==0);
  }
  unixBigLock = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS1);

#ifndef SQLITE_OMIT_WAL
  /* Validate lock assumptions */
  assert( SQLITE_SHM_NLOCK==8 );  /* Number of available locks */
  assert( UNIX_SHM_BASE==120  );  /* Start of locking area */
  /* Locks:
  **    WRITE       UNIX_SHM_BASE      120
  **    CKPT        UNIX_SHM_BASE+1    121
  **    RECOVER     UNIX_SHM_BASE+2    122
  **    READ-0      UNIX_SHM_BASE+3    123
  **    READ-1      UNIX_SHM_BASE+4    124
  **    READ-2      UNIX_SHM_BASE+5    125
  **    READ-3      UNIX_SHM_BASE+6    126
  **    READ-4      UNIX_SHM_BASE+7    127
  **    DMS         UNIX_SHM_BASE+8    128
  */
  assert( UNIX_SHM_DMS==128   );  /* Byte offset of the deadman-switch */
#endif

  return SQLITE_OK; 
}

/*
** Shutdown the operating system interface.
**
** Some operating systems might need to do some cleanup in this routine,