bwb_mth.c

这是一个简易的basic语言解释器, 可供我们学习和改进.

#if ANSI_C
struct bwb_variable *
fnc_log( int argc, struct bwb_variable *argv, int unique_id  )
#else
struct bwb_variable *
fnc_log( argc, argv, unique_id  )
   int argc;
   struct bwb_variable *argv;
   int unique_id;
#endif
   {
   static struct bwb_variable nvar;
   static int init = FALSE;

   /* initialize the variable if necessary */

   if ( init == FALSE )
      {
      init = TRUE;
      var_make( &nvar, NUMBER );
      }

#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "in fnc_log(): received f_arg <%f> ",
      var_getnval( &( argv[ 0 ] ) ) );
   bwb_debug( bwb_ebuf );
#endif

#if PROG_ERRORS
   if ( argc < 1 )
      {
      sprintf( bwb_ebuf, "Not enough parameters (%d) to function LOG().",
         argc );
      bwb_error( bwb_ebuf );
      return NULL;
      }
   else if ( argc > 1 )
      {
      sprintf( bwb_ebuf, "Too many parameters (%d) to function LOG().",
         argc );
      bwb_error( bwb_ebuf );
      return NULL;
      }
#else
   if ( fnc_checkargs( argc, argv, 1, 1 ) == FALSE )
      {
      return NULL;
      }
#endif

   /* assign values */

   * var_findnval( &nvar, nvar.array_pos ) 
      = (bnumber) log( (double) var_getnval( &( argv[ 0 ] ) ) );

   return &nvar;
   }

/***************************************************************

        FUNCTION:       fnc_sin()

        DESCRIPTION:    This C function implements the BASIC
                        predefined SIN function, returning
                        the sine of the argument.

	SYNTAX:		SIN( number )

***************************************************************/

#if ANSI_C
struct bwb_variable *
fnc_sin( int argc, struct bwb_variable *argv, int unique_id  )
#else
struct bwb_variable *
fnc_sin( argc, argv, unique_id  )
   int argc;
   struct bwb_variable *argv;
   int unique_id;
#endif
   {
   static struct bwb_variable nvar;
   static int init = FALSE;

   /* initialize the variable if necessary */

   if ( init == FALSE )
      {
      init = TRUE;
      var_make( &nvar, NUMBER );
      }

#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "in fnc_sin(): received f_arg <%f> ",
      var_getnval( &( argv[ 0 ] ) ) );
   bwb_debug( bwb_ebuf );
#endif

#if PROG_ERRORS
   if ( argc < 1 )
      {
      sprintf( bwb_ebuf, "Not enough parameters (%d) to function SIN().",
         argc );
      bwb_error( bwb_ebuf );
      return NULL;
      }

   else if ( argc > 1 )
      {
      sprintf( bwb_ebuf, "Too many parameters (%d) to function SIN().",
         argc );
      bwb_error( bwb_ebuf );
      return NULL;
      }
#else
   if ( fnc_checkargs( argc, argv, 1, 1 ) == FALSE )
      {
      return NULL;
      }
#endif

   /* assign values */

   * var_findnval( &nvar, nvar.array_pos ) 
      = (bnumber) sin( (double) var_getnval( &( argv[ 0 ] ) ) );

   return &nvar;

   }


/***************************************************************

        FUNCTION:       fnc_sqr()

        DESCRIPTION:    This C function implements the BASIC
                        predefined SQR function, returning
                        the square root of the argument.

	SYNTAX:		SQR( number )

***************************************************************/

#if ANSI_C
struct bwb_variable *
fnc_sqr( int argc, struct bwb_variable *argv, int unique_id  )
#else
struct bwb_variable *
fnc_sqr( argc, argv, unique_id  )
   int argc;
   struct bwb_variable *argv;
   int unique_id;
#endif
   {
   static struct bwb_variable nvar;
   static int init = FALSE;

   /* initialize the variable if necessary */

   if ( init == FALSE )
      {
      init = TRUE;
      var_make( &nvar, NUMBER );
      }

#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "in fnc_sqr(): received f_arg <%f> ",
      var_getnval( &( argv[ 0 ] ) ) );
   bwb_debug( bwb_ebuf );
#endif

#if PROG_ERRORS
   if ( argc < 1 )
      {
      sprintf( bwb_ebuf, "Not enough parameters (%d) to function SQR().",
         argc );
      bwb_error( bwb_ebuf );
      return NULL;
      }
   else if ( argc > 1 )
      {
      sprintf( bwb_ebuf, "Too many parameters (%d) to function SQR().",
         argc );
      bwb_error( bwb_ebuf );
      return NULL;
      }
#else
   if ( fnc_checkargs( argc, argv, 1, 1 ) == FALSE )
      {
      return NULL;
      }
#endif

   /* assign values */

   * var_findnval( &nvar, nvar.array_pos ) 
      = (bnumber) sqrt( (double) var_getnval( &( argv[ 0 ] ) ) );

   return &nvar;

   }

/***************************************************************

        FUNCTION:       fnc_tan()

        DESCRIPTION:    This C function implements the BASIC
                        predefined TAN function, returning the
                        tangent of the argument.

	SYNTAX:		TAN( number )

***************************************************************/

#if ANSI_C
struct bwb_variable *
fnc_tan( int argc, struct bwb_variable *argv, int unique_id  )
#else
struct bwb_variable *
fnc_tan( argc, argv, unique_id  )
   int argc;
   struct bwb_variable *argv;
   int unique_id;
#endif
   {
   static struct bwb_variable nvar;
   static int init = FALSE;

   /* initialize the variable if necessary */

   if ( init == FALSE )
      {
      init = TRUE;
      var_make( &nvar, NUMBER );
      }

#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "in fnc_tan(): received f_arg <%f> ",
      var_getnval( &( argv[ 0 ] ) ) );
   bwb_debug( bwb_ebuf );
#endif

#if PROG_ERRORS
   if ( argc < 1 )
      {
      sprintf( bwb_ebuf, "Not enough parameters (%d) to function TAN().",
         argc );
      bwb_error( bwb_ebuf );
      return NULL;
      }
   else if ( argc > 1 )
      {
      sprintf( bwb_ebuf, "Too many parameters (%d) to function TAN().",
         argc );
      bwb_error( bwb_ebuf );
      return NULL;
      }
#else
   if ( fnc_checkargs( argc, argv, 1, 1 ) == FALSE )
      {
      return NULL;
      }
#endif

   /* assign values */

   * var_findnval( &nvar, nvar.array_pos ) 
      = (bnumber) tan( (double) var_getnval( &( argv[ 0 ] ) ) );

   return &nvar;

   }


/***************************************************************

        FUNCTION:       fnc_sgn()

        DESCRIPTION:    This C function implements the BASIC
                        predefined SGN function, returning 0
                        if the argument is 0, -1 if the argument
                        is less than 0, or 1 if the argument
                        is more than 0.

	SYNTAX:		SGN( number )

***************************************************************/

#if ANSI_C
struct bwb_variable *
fnc_sgn( int argc, struct bwb_variable *argv, int unique_id  )
#else
struct bwb_variable *
fnc_sgn( argc, argv, unique_id  )
   int argc;
   struct bwb_variable *argv;
   int unique_id;
#endif
   {
   static struct bwb_variable nvar;
   bnumber nval;
   static int init = FALSE;

   /* initialize the variable if necessary */

   if ( init == FALSE )
      {
      init = TRUE;
      var_make( &nvar, NUMBER );
      }

#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "in fnc_sgn(): received f_arg <%f> ",
      var_getnval( &( argv[ 0 ] ) ) );
   bwb_debug( bwb_ebuf );
#endif

#if PROG_ERRORS
   if ( argc < 1 )
      {
      sprintf( bwb_ebuf, "Not enough parameters (%d) to function SGN().",
         argc );
      bwb_error( bwb_ebuf );
      return NULL;
      }
   else if ( argc > 1 )
      {
      sprintf( bwb_ebuf, "Too many parameters (%d) to function SGN().",
         argc );
      bwb_error( bwb_ebuf );
      return NULL;
      }
#else
   if ( fnc_checkargs( argc, argv, 1, 1 ) == FALSE )
      {
      return NULL;
      }
#endif

   /* assign values */

   nval = var_getnval( &( argv[ 0 ] ));

   if ( nval == (bnumber) 0.0 )
      {
      * var_findnval( &nvar, nvar.array_pos ) = (bnumber) 0;
      }
   else if ( nval > (bnumber) 0.0 )
      {
      * var_findnval( &nvar, nvar.array_pos ) = (bnumber) 1;
      }
   else
      {
      * var_findnval( &nvar, nvar.array_pos ) = (bnumber) -1;
      }

   return &nvar;
   }

/***************************************************************

        FUNCTION:       fnc_int()

        DESCRIPTION:    This C function implements the BASIC
                        predefined INT function, returning an
                        integer value less then or equal to the 
			argument.

	SYNTAX:		INT( number )

***************************************************************/

#if ANSI_C
struct bwb_variable *
fnc_int( int argc, struct bwb_variable *argv, int unique_id  )
#else
struct bwb_variable *
fnc_int( argc, argv, unique_id  )
   int argc;
   struct bwb_variable *argv;
   int unique_id;
#endif
   {
   static struct bwb_variable nvar;
   static int init = FALSE;

   /* initialize the variable if necessary */

   if ( init == FALSE )
      {
      init = TRUE;
      var_make( &nvar, NUMBER );
      }

#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "in fnc_int(): received f_arg <%f> ",
      var_getnval( &( argv[ 0 ] ) ) );
   bwb_debug( bwb_ebuf );
#endif

#if PROG_ERRORS
   if ( argc < 1 )
      {
      sprintf( bwb_ebuf, "Not enough parameters (%d) to function INT().",
         argc );
      bwb_error( bwb_ebuf );
      return NULL;
      }
   else if ( argc > 1 )
      {
      sprintf( bwb_ebuf, "Too many parameters (%d) to function INT().",
         argc );
      bwb_error( bwb_ebuf );
      return NULL;
      }
#else
   if ( fnc_checkargs( argc, argv, 1, 1 ) == FALSE )
      {
      return NULL;
      }
#endif

   /* assign values */

   * var_findnval( &nvar, nvar.array_pos ) 
      = (bnumber) floor( (double) var_getnval( &( argv[ 0 ] ) ) );

   return &nvar;
   }

/***************************************************************

        FUNCTION:       fnc_exp()

	DESCRIPTION:    This C function implements the BASIC
			EXP() function, returning the exponential
			value of the argument.

	SYNTAX:		EXP( number )

***************************************************************/

#if ANSI_C
struct bwb_variable *
fnc_exp( int argc, struct bwb_variable *argv, int unique_id )
#else
struct bwb_variable *
fnc_exp( argc, argv, unique_id )
   int argc;
   struct bwb_variable *argv;
   int unique_id;
#endif
   {
   static struct bwb_variable nvar;
   static int init = FALSE;

   /* initialize the variable if necessary */

   if ( init == FALSE )
      {
      init = TRUE;
      var_make( &nvar, NUMBER );
      }

#if PROG_ERRORS
   if ( argc < 1 )
      {
      sprintf( bwb_ebuf, "Not enough parameters (%d) to function EXP().",
         argc );
      bwb_error( bwb_ebuf );
      return NULL;
      }

   else if ( argc > 1 )
      {
      sprintf( bwb_ebuf, "Too many parameters (%d) to function EXP().",
         argc );
      bwb_error( bwb_ebuf );
      return NULL;
      }
#else
   if ( fnc_checkargs( argc, argv, 1, 1 ) == FALSE )
      {
      return NULL;
      }
#endif

   /* assign values */

   /* Added double recast here (JBV) */
   * var_findnval( &nvar, nvar.array_pos ) 
      = (bnumber) exp( (double) var_getnval( &( argv[ 0 ] ) ) );

   return &nvar;
   }

#endif                          /* COMPRESS_FUNCS */

#if COMMON_FUNCS

/***************************************************************

        FUNCTION:       fnc_val()

	DESCRIPTION:    This C function implements the BASIC
			VAL() function, returning the numerical
			value of its string argument.

	SYNTAX:		VAL( string$ )

***************************************************************/