VSPACE

VSPACE processes all virtual space operations. Multiple virtual screens may exist, limited only by the amount of memory available. Data may be written to a virtual screen, and for each screen, a window may be defined in order to view the data (see Appendix 4, Virtual Space). The virtual space operations are described in the operator parameter below.

Determines the type of operation a call to VSPACE is to perform. Note that the VBACK operation must precede those operations affecting the definition or placement of a window (see the appropriate op.parameters description).

The following are the definitions for the VSPACE operators (these are also defined in the VIRTUAL.PARAMS record of the UTILITY.PROGS file):

EQU VINIT TO  1 
EQU VSIZE TO  2 
EQU VBACK TO  3 
EQU VPRNT TO  4 
EQU VWMOV TO  5 
EQU VWEXP TO  6 
EQU VWPAN TO  7 
EQU VCPOS TO 10 
EQU VGETC TO 11 
EQU VGETA TO 12 
EQU VSAVE TO 13 
EQU VRSTR TO 14 
EQU VSCRL TO 15 
EQU VWGET TO 16 
EQU VWSET TO 17 
EQU VPOFF TO 18 
EQU VSOFF TO 19 
 
EQU VON     TO  5         ;* a constant 
EQU VOFFSET TO 26         ;* a constant 

The following operations are available:

A variable used by VSPACE to return an integer value indicating the status of the operation performed:

A variable used by VSPACE to store the virtual screen image defined. Note that the exception to this is when used with the VBACK operator. In this case, screen refers to the previous display image and must be a different variable than that used to store the virtual screen image.

These parameters are dependent upon the operator specified. The parameters are to be treated as normal argument list parameters (delimited by commas). The following is a listing of the requirements for each operator, and a description of the values expected:

vrow are the column and row integer offsets into the virtual screen. The size of a window is limited to the size of the display (CRT). VWSET must be preceded by a call to VBACK, display being the screen value (previous display image) returned by VBACK.|

vrow are the column and row integer offsets into the virtual screen. VWGET must be preceded by a call to VBACK, display being the screen value (previous display image) returned by VBACK.|

VSPACE may pass a value in an op.parameters variable of the argument list. This depends on the operator used.

*Initialization 
DECLARE SUBROUTINE VSPACE,MSG,BORDER.UP 
$INSERT UTILITY.PROGS,VIRTUAL.PARAMS 
 
*Create and store a virtual screen 160 x 160 for use in 
*subsequent operations 
COLS = 160 
ROWS = 160 
VSPACE(VINIT,STATUS,VSCREEN,COLS,ROWS) 
 
*Write a string to the virtual screen 
IF STATUS = 0 THEN 
COL = 1 
ROW = 1 
 
VSPACE(VPRNT,STATUS,VSCREEN,COL,ROW,"Press [Enter] to continue") 
END ELSE 
MSG('VSPACE error: %1%','','',STATUS) 
END 
 
*Return and display a character from the virtual screen 
IF STATUS = 0 THEN 
VSPACE(VGETC,STATUS,VSCREEN,3,1,CHAR) 
MSG('The character at the virtual screen coordinates is: %1%','','',CHAR) 
END ELSE 
MSG('VSPACE error: %1%','','',STATUS) 
END 
 
*Save and clear the current display image. The cleared screen 
*will serve as the referential display for subsequent 
*window operations 
IF STATUS = 0 THEN 
VIDEO.RW(0,0,@CRTWIDE-1,@CRTMAXHIGH-1,'R',IMAGE) 
VIDEO.RW(0,0,@CRTWIDE-1,@CRTMAXHIGH-1,'C','') 
VSPACE(VBACK,STATUS,DISPLAY,@CRTWIDE-1,@CRTMAXHIGH-1) 
END ELSE 
MSG('VSPACE error: %1%','','',STATUS) 
END 
 
*Set parameters for a window in the current virtual screen, and 
*display the window with a border (see the system subroutine 
*BORDER.UP) 
IF STATUS = 0 THEN 
LEFT.COL = 10 
TOP = 6 
RIGHT.COL = 35 
BOTTOM = 8 
VCOL = 1 
VROW = 1 
 
VSPACE(VWSET,STATUS,VSCREEN,LEFT.COL,TOP,RIGHT.COL, BOTTOM,VCOL,VROW,DISPLAY) 
BORDER.UP(LEFT.COL-1,TOP- 1,RIGHT.COL+1,BOTTOM+1,2,'') 
MSG('The window is defined and displayed.|Next the display is cleared and the window is moved.','','','') 
END ELSE 
MSG('VSPACE error: %1%','','',STATUS) 
END 
 
*Clear the screen and move the window up 
IF STATUS = 0 THEN 
VIDEO.RW(0,0,@CRTWIDE-1,@CRTMAXHIGH-1,'C','') 
MOV.COLS = 0 
MOV.ROWS = -5 
TOP += MOV.ROWS 
BOTTOM += MOV.ROWS 
 
VSPACE(VWMOV,STATUS,VSCREEN,MOV.COLS,MOV.ROWS,DISPLAY,1) 
BORDER.UP(LEFT.COL-1,TOP-1,RIGHT.COL+1,BOTTOM+1,2,'') 
MSG('Finally, the window is expanded.','','','') 
END ELSE 
MSG('VSPACE error: %1%','','',STATUS) 
END 
 
*Clear the screen and expand the previously defined window,  
*restoring the previous display image as the final operation 
IF STATUS = 0 THEN 
VIDEO.RW(0,0,@CRTWIDE-1,@CRTMAXHIGH-1,'C','') 
EXP.COLS = 10 
EXP.ROWS = 10 
RIGHT.COL += EXP.COLS 
BOTTOM += EXP.ROWS 
 
VSPACE(VWEXP,STATUS,VSCREEN,EXP.COLS,EXP.ROWS,DISPLAY,0) 
BORDER.UP(LEFT.COL-1,TOP-1,RIGHT.COL+1,BOTTOM+1,2,'') 
MSG('The window may be as large as the display.','','','') 
VIDEO.RW(0,0,@CRTWIDE-1,@CRTMAXHIGH-1,'W',IMAGE) 
END ELSE 
MSG('VSPACE error: %1%','','',STATUS) 
END