bwb_fnc.c

这是一个简易的basic语言解释器, 可供我们学习和改进.

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

        bwb_fnc.c       Interpretation Routines
			for Predefined Functions
                        for Bywater BASIC Interpreter

                        Copyright (c) 1993, Ted A. Campbell
                        Bywater Software

                        email: [e-mail]

        Copyright and Permissions Information:

        All U.S. and international rights are claimed by the author,
        Ted A. Campbell.

	This software is released under the terms of the GNU General
	Public License (GPL), which is distributed with this software
	in the file "COPYING".  The GPL specifies the terms under
	which users may copy and use the software in this distribution.

	A separate license is available for commercial distribution,
	for information on which you should contact the author.

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

/*---------------------------------------------------------------*/
/* NOTE: Modifications marked "JBV" were made by Jon B. Volkoff, */
/* 11/1995 ([e-mail]).                                  */
/*---------------------------------------------------------------*/

#define FSTACKSIZE      32

#include <stdio.h>
#include <ctype.h>
#include <math.h>
#include <time.h>

#include "bwbasic.h"
#include "bwb_mes.h"

#if UNIX_CMDS
#include <sys/stat.h>
#endif

#ifndef RAND_MAX			/* added in v1.11 */
#define RAND_MAX	32767
#endif

static time_t t;
static struct tm *lt;

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

        FUNCTION:       fnc_init()

        DESCRIPTION:    This command initializes the function
                        linked list, placing all predefined functions
                        in the list.

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

#if ANSI_C
int
fnc_init( int task )
#else
int
fnc_init( task )
   int task;
#endif
   {
   register int n;
   struct bwb_function *f;

   strcpy( LOCALTASK fnc_start.name, "FNC_START" );
   LOCALTASK fnc_start.type = 'X';
   LOCALTASK fnc_start.vector = fnc_null;
   strcpy( LOCALTASK fnc_end.name, "FNC_END" );
   LOCALTASK fnc_end.type = 'x';
   LOCALTASK fnc_end.vector = fnc_null;
   LOCALTASK fnc_end.next = &LOCALTASK fnc_end;

   f = &LOCALTASK fnc_start;

   /* now go through each of the preestablished functions and set up
      links between them; from this point the program address the functions
      only as a linked list (not as an array) */

   for ( n = 0; n < FUNCTIONS; ++n )
      {
      f->next = &( bwb_prefuncs[ n ] );
      f = f->next;
      }

   /* link the last pointer to the end; this completes the list */

   f->next = &LOCALTASK fnc_end;

   return TRUE;
   }

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

        FUNCTION:       fnc_find()

        DESCRIPTION:    This C function attempts to locate
                        a BASIC function with the specified name.
                        If successful, it returns a pointer to
                        the C structure for the BASIC function,
                        if not successful, it returns NULL.

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

#if ANSI_C
struct bwb_function *
fnc_find( char *buffer )
#else
struct bwb_function *
fnc_find( buffer )
   char *buffer;
#endif
   {
   struct bwb_function * f;
   register int n;
   static char *tbuf;
   static int init = FALSE;

   if ( strlen( buffer ) == 0 )
      {
      return NULL;
      }

   /* get memory for temporary buffer if necessary */

   if ( init == FALSE )
      {
      init = TRUE;

      /* Revised to CALLOC pass-thru call by JBV */
      if ( ( tbuf = CALLOC( MAXSTRINGSIZE + 1, sizeof( char ), "fnc_find" )) == NULL )
         {
#if PROG_ERRORS
	 bwb_error( "in fnc_find(): failed to find memory for tbuf" );
#else
	 bwb_error( err_getmem );
#endif
	 }
      }

#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "in fnc_find(): called for <%s> ", buffer );
   bwb_debug( bwb_ebuf );
#endif

   strcpy( tbuf, buffer );
   bwb_strtoupper( tbuf );

   for ( f = CURTASK fnc_start.next; f != &CURTASK fnc_end; f = f->next )
      {
      if ( strcmp( f->name, tbuf ) == 0 )
         {
#if INTENSIVE_DEBUG
	 sprintf( bwb_ebuf, "in fnc_find(): found <%s> ", f->name );
	 bwb_debug( bwb_ebuf );
#endif
         return f;
         }
      }

   /* search has failed: return NULL */

   return NULL;

   }

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

        FUNCTION:       fnc_null()

        DESCRIPTION:    This is a null function that can be used
                        to fill in a required function-structure
                        pointer when needed.

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

#if ANSI_C
struct bwb_variable *
fnc_null( int argc, struct bwb_variable *argv, int unique_id )
#else
struct bwb_variable *
fnc_null( 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 );
      }

   return &nvar;
   }

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

        FUNCTION:       fnc_tab()

	DESCRIPTION:    This C function implements the BASIC TAB()
			function, adding tab spaces to a specified
			column.

			TAB is a core function, i.e., required
			for ANSI Minimal BASIC.

	SYNTAX:		TAB( number )

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

#if ANSI_C
struct bwb_variable *
fnc_tab( int argc, struct bwb_variable *argv, int unique_id )
#else
struct bwb_variable *
fnc_tab( argc, argv, unique_id )
   int argc;
   struct bwb_variable *argv;
   int unique_id;
#endif
   {
   static struct bwb_variable nvar;
   static int init = FALSE;
   static char t_string[ 4 ];
   bstring *b;

   /* initialize nvar if necessary */

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

   /* check for correct number of parameters */

   if ( argc < 1 )
      {
#if PROG_ERRORS
      sprintf( bwb_ebuf, "Not enough parameters (%d) to function TAB().",
         argc );
      bwb_error( bwb_ebuf );
#else
      bwb_error( err_syntax );
#endif
      break_handler();
      return NULL;
      }
   else if ( argc > 1 )
      {
#if PROG_ERRORS
      sprintf( bwb_ebuf, "Too many parameters (%d) to function TAB().",
         argc );
      bwb_error( bwb_ebuf );
#else
      bwb_error( err_syntax );
#endif
      break_handler();
      return NULL;
      }

   t_string[ 0 ] = PRN_TAB;
   t_string[ 1 ] = (char) var_getnval( &( argv[ 0 ] ));
   t_string[ 2 ] = '\0';

   b = var_getsval( &nvar );
   str_ctob( b, t_string );

   return &nvar;
   }

#if COMMON_FUNCS

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


        FUNCTION:       fnc_date()

        DESCRIPTION:    This C function implements the BASIC
                        predefined DATE$ function, returning
                        a string containing the year, month,
                        and day of the month.

	SYNTAX:		DATE$

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

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

   /* initialize the variable if necessary */

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

      /* Revised to CALLOC pass-thru call by JBV */
      if ( ( tbuf = CALLOC( MAXSTRINGSIZE + 1, sizeof( char ), "fnc_date" )) == NULL )
         {
#if PROG_ERRORS
         bwb_error( "in fnc_date(): failed to get memory for tbuf" );
#else
         bwb_error( err_getmem );
#endif
         }
      }

   time( &t );
   lt = localtime( &t );

   sprintf( tbuf, "%02d-%02d-%04d", lt->tm_mon + 1, lt->tm_mday,
      1900 + lt->tm_year );
   str_ctob( var_findsval( &nvar, nvar.array_pos ), tbuf );

   return &nvar;
   }

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

        FUNCTION:       fnc_time()

        DESCRIPTION:    This C function implements the BASIC
                        predefined TIME$ function, returning a
                        string containing the hour, minute, and
                        second count.

	SYNTAX:		TIME$

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

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

   /* initialize the variable if necessary */

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

      /* Revised to CALLOC pass-thru call by JBV */
      if ( ( tbuf = CALLOC( MAXSTRINGSIZE + 1, sizeof( char ), "fnc_time" )) == NULL )
         {
#if PROG_ERRORS
         bwb_error( "in fnc_time(): failed to get memory for tbuf" );
#else
         bwb_error( err_getmem );
#endif
         }
      }

   time( &t );
   lt = localtime( &t );

   sprintf( tbuf, "%02d:%02d:%02d", lt->tm_hour, lt->tm_min,
      lt->tm_sec );
   str_ctob( var_findsval( &nvar, nvar.array_pos ), tbuf );

   return &nvar;
   }

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

        FUNCTION:       fnc_chr()

        DESCRIPTION:    This C function implements the BASIC
                        predefined CHR$ function, returning a
                        string containing the single character
                        whose ASCII value is the argument to
                        this function.

	SYNTAX:		CHR$( number )

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

#if ANSI_C
struct bwb_variable *
fnc_chr( int argc, struct bwb_variable *argv, int unique_id  )
#else
struct bwb_variable *
fnc_chr( argc, argv, unique_id  )
   int argc;
   struct bwb_variable *argv;
   int unique_id;
#endif
   {
   static struct bwb_variable nvar;
   char tbuf[ MAXSTRINGSIZE + 1 ];
   static int init = FALSE;
#if TEST_BSTRING
   bstring *b;
#endif

#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "in fnc_chr(): entered function, argc <%d>",
      argc );
   bwb_debug( bwb_ebuf );
#endif

   /* initialize the variable if necessary */

   if ( init == FALSE )
      {
      init = TRUE;
      var_make( &nvar, STRING );
#if INTENSIVE_DEBUG
      sprintf( bwb_ebuf, "in fnc_chr(): entered function, initialized nvar" );
      bwb_debug( bwb_ebuf );
#endif
      }

   /* check arguments */

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

#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "in fnc_chr(): entered function, checkargs ok" );
   bwb_debug( bwb_ebuf );
#endif

   tbuf[ 0 ] = (char) var_getnval( &( argv[ 0 ] ) );
   tbuf[ 1 ] = '\0';
   str_ctob( var_findsval( &nvar, nvar.array_pos ), tbuf );

#if TEST_BSTRING
   b = var_findsval( &nvar, nvar.array_pos );
   sprintf( bwb_ebuf, "in fnc_chr(): bstring name is <%s>", b->name );
   bwb_debug( bwb_ebuf );
#endif
#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "in fnc_chr(): tbuf[ 0 ] is <%c>", tbuf[ 0 ] );
   bwb_debug( bwb_ebuf );
#endif

   return &nvar;
   }

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

        FUNCTION:       fnc_len()

	DESCRIPTION:    This C function implements the BASIC LEN()
			function, returning the length of a
			specified string in bytes.

	SYNTAX:		LEN( string$ )

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

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

   /* initialize the variable if necessary */

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

      /* Revised to CALLOC pass-thru call by JBV */
      if ( ( tbuf = CALLOC( MAXSTRINGSIZE + 1, sizeof( char ), "fnc_len" )) == NULL )
         {
#if PROG_ERRORS
         bwb_error( "in fnc_len(): failed to get memory for tbuf" );
#else
         bwb_error( err_getmem );
#endif
         }
      }

   /* check parameters */

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

   /* return length as an integer */

   str_btoc( tbuf, var_getsval( &( argv[ 0 ] )) );
   * var_findnval( &nvar, nvar.array_pos )
      = (bnumber) strlen( tbuf );

   return &nvar;
   }

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

        FUNCTION:       fnc_pos()

	DESCRIPTION:    This C function implements the BASIC
			POS() function, returning the current
			column position for the output device.

	SYNTAX:		POS

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

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

   /* initialize nvar if necessary */

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

   * var_findnval( &nvar, nvar.array_pos ) = (bnumber) prn_col;

   return &nvar;
   }

#endif					/* COMMON_FUNCS */

#if MS_FUNCS

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

        FUNCTION:       fnc_timer()

        DESCRIPTION:    This C function implements the BASIC
                        predefined TIMER function

	SYNTAX:		TIMER

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

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

   /* initialize the variable if necessary */

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