bwx_iqc.c

这是一个简易的basic语言解释器, 可供我们学习和改进.

   union REGS ibm_registers;

   /* call the BDOS function 0x10 to read the current cursor position */

   ibm_registers.h.ah = 3;
   ibm_registers.h.bh = (unsigned char) _getvisualpage();
   int86( 0x10, &ibm_registers, &ibm_registers );

   /* set text to this position */

   _settextposition( ibm_registers.h.dh, ibm_registers.h.dl );

   /* and move down one position */

   prn_xprintf( stdout, "\n" );

   return TRUE;
   }


#if COMMON_CMDS

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

        FUNCTION:       bwb_edit()

        DESCRIPTION:

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

struct bwb_line *
bwb_edit( struct bwb_line *l )
   {
   char tbuf[ MAXSTRINGSIZE + 1 ];
   char edname[ MAXSTRINGSIZE + 1 ];
   struct bwb_variable *ed;
   FILE *loadfile;

   ed = var_find( DEFVNAME_EDITOR );
   str_btoc( edname, var_getsval( ed ));

   sprintf( tbuf, "%s %s", edname, CURTASK progfile );

#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "in bwb_edit(): command line <%s>", tbuf );
   bwb_debug( bwb_ebuf );
#else
   system( tbuf );
#endif

   /* open edited file for read */

   if ( ( loadfile = fopen( CURTASK progfile, "r" )) == NULL )
      {
      sprintf( bwb_ebuf, err_openfile, CURTASK progfile );
      bwb_error( bwb_ebuf );

      iqc_setpos();
      return bwb_zline( l );
      }

   /* clear current contents */

   bwb_new( l ); /* Relocated by JBV (bug found by DD) */

   /* and (re)load the file into memory */

   bwb_fload( loadfile );


   iqc_setpos();
   return bwb_zline( l );
   }

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

        FUNCTION:       bwb_renum()

	DESCRIPTION:    This function implements the BASIC RENUM
			command by shelling out to a default
			renumbering program called "renum".
			Added by JBV 10/95

	SYNTAX:		RENUM

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

#if ANSI_C
struct bwb_line *
bwb_renum( struct bwb_line *l )
#else
struct bwb_line *
bwb_renum( l )
   struct bwb_line *l;
#endif
   {
   char tbuf[ MAXSTRINGSIZE + 1 ];
   FILE *loadfile;

   sprintf( tbuf, "renum %s\0", CURTASK progfile );

#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "in bwb_renum(): command line <%s>", tbuf );
   bwb_debug( bwb_ebuf );
#else
   system( tbuf );
#endif

   /* open edited file for read */

   if ( ( loadfile = fopen( CURTASK progfile, "r" )) == NULL )
      {
      sprintf( bwb_ebuf, err_openfile, CURTASK progfile );
      bwb_error( bwb_ebuf );

      iqc_setpos();
      return bwb_zline( l );
      }

   /* clear current contents */

   bwb_new( l ); /* Relocated by JBV (bug found by DD) */

   /* and (re)load the file into memory */

   bwb_fload( loadfile );


   iqc_setpos();
   return bwb_zline( l );
   }

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

        FUNCTION:       bwb_files()

        DESCRIPTION:

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

struct bwb_line *
bwb_files( struct bwb_line *l )
   {
   char tbuf[ MAXVARNAMESIZE + 1 ];
   char finame[ MAXVARNAMESIZE + 1 ];
   char argument[ MAXVARNAMESIZE + 1 ];
   struct bwb_variable *fi;
   struct exp_ese *e;

   fi = var_find( DEFVNAME_FILES );
   str_btoc( finame, var_getsval( fi ));

   /* get argument */

   adv_ws( l->buffer, &( l->position ));
   switch( l->buffer[ l->position ] )
      {
      case '\0':
      case '\r':
      case '\n':
         argument[ 0 ] = '\0';
         break;
      default:
         e = bwb_exp( l->buffer, FALSE, &( l->position ) );
         if ( e->type != STRING )
            {
            bwb_error( err_mismatch );
            return bwb_zline( l );
            }
         str_btoc( argument, exp_getsval( e ) );
         break;
      }


   sprintf( tbuf, "%s %s", finame, argument );

#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "in bwb_files(): command line <%s>", tbuf );
   bwb_debug( bwb_ebuf );
#else
   system( tbuf );
#endif

   iqc_setpos();
   return bwb_zline( l );

   }

#endif					/* COMMON_CMDS */

#if INTERACTIVE

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

        FUNCTION:       fnc_inkey()

        DESCRIPTION:    This C function implements the BASIC INKEY$
        		function.  It is implementation-specific.

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

extern struct bwb_variable *
fnc_inkey( int argc, struct bwb_variable *argv )
   {
   static struct bwb_variable nvar;
   char tbuf[ MAXSTRINGSIZE + 1 ];
   static int init = FALSE;

   /* initialize the variable if necessary */

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

   /* check arguments */

#if PROG_ERRORS
   if ( argc > 0 )
      {
      sprintf( bwb_ebuf, "Two many arguments to function INKEY$()" );
      bwb_error( bwb_ebuf );
      return &nvar;
      }

#else
   if ( fnc_checkargs( argc, argv, 0, 0 ) == FALSE )
      {
      return NULL;
      }
#endif

   /* body of the INKEY$ function */

   if ( _bios_keybrd( _KEYBRD_READY ) == 0 )
      {
      tbuf[ 0 ] = '\0';
      }
   else
      {
      tbuf[ 0 ] = (char) _bios_keybrd( _KEYBRD_READ );
      tbuf[ 1 ] = '\0';
      }

   /* assign value to nvar variable */

   str_ctob( var_findsval( &nvar, nvar.array_pos ), tbuf );

   /* return value contained in nvar */

   return &nvar;

   }

#endif				/* INTERACTIVE */

#if MS_CMDS

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

        FUNCTION:       bwb_cls()

        DESCRIPTION:    This C function implements the BASIC CLS
        		command.  It is implementation-specific.

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

extern struct bwb_line *
bwb_cls( struct bwb_line *l )
   {

   _clearscreen( _GCLEARSCREEN );

   return bwb_zline( l );
   }

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

        FUNCTION:       bwb_locate()

        DESCRIPTION:    This C function implements the BASIC LOCATE
        		command.  It is implementation-specific.

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

extern struct bwb_line *
bwb_locate( struct bwb_line *l )
   {
   struct exp_ese *e;
   int row, column;

   /* get first argument */

   e = bwb_exp( l->buffer, FALSE, &( l->position ));
   row = (int) exp_getnval( e );

   /* advance past comma */

   adv_ws( l->buffer, &( l->position ));
   if ( l->buffer[ l->position ] != ',' )
      {
      bwb_error( err_syntax );
      return bwb_zline( l );
      }
   ++( l->position );

   /* get second argument */

   e = bwb_exp( l->buffer, FALSE, &( l->position ));
   column = (int) exp_getnval( e );

   /* position the cursor */

   _settextposition( row, column );

   return bwb_zline( l );
   }

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

	FUNCTION:       bwb_color()

	DESCRIPTION:    This C function implements the BASIC COLOR
			command.  It is implementation-specific.

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

extern struct bwb_line *
bwb_color( struct bwb_line *l )
   {
   struct exp_ese *e;
   int color;

   /* get first argument */

   e = bwb_exp( l->buffer, FALSE, &( l->position ));
   color = (int) exp_getnval( e );

#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "Setting text color to %d", color );
   bwb_debug( bwb_ebuf );
#endif

   _settextcolor( (short) color );

#if INTENSIVE_DEBUG
   sprintf( bwb_ebuf, "Set text color to %d", color );
   bwb_debug( bwb_ebuf );
#endif

   /* advance past comma */

   adv_ws( l->buffer, &( l->position ));
   if ( l->buffer[ l->position ] == ',' )
      {

      ++( l->position );

      /* get second argument */

      e = bwb_exp( l->buffer, FALSE, &( l->position ));
      color = (int) exp_getnval( e );

#if INTENSIVE_DEBUG
      sprintf( bwb_ebuf, "Setting background color to %d", color );
      bwb_debug( bwb_ebuf );
#endif

      /* set the background color */

      _setbkcolor( (long) color );

#if INTENSIVE_DEBUG
      sprintf( bwb_ebuf, "Setting background color to %d\n", color );
      bwb_debug( bwb_ebuf );
#endif

      }

   return bwb_zline( l );
   }

#endif				/* MS_CMDS */