| Function | Description |
|---|---|
| disp_box | Draws a box. |
| disp_close | Closes the display. |
| disp_eeol | Erases to the end of current line. |
| disp_eeop | Erases to the end of the page. |
| disp_endstand | Ends reverse video mode. |
| disp_fillbox | Fills the box. |
| disp_flush | Moves the cursor to coincide with output position. |
| disp_getattr | Gets display attributes. |
| disp_getmode | Gets the current video mode. |
| disp_hidecursor | Hides the cursor. |
| disp_move | Moves the cursor position. |
| disp_open | Initializes the display. |
| disp_peekbox | Stores a defined rectangular area. |
| disp_peekw | Reads the information at specified position defined by row/column. |
| disp_pokebox | Restores a previously defined rectangular area. |
| disp_pokew | Puts an attribute/character into a specified row/column. |
| disp_printf | Writes to the screen. |
| disp_putc | Writes a character to an output location. |
| disp_puts | Writes a string to an output location. |
| disp_reset43 | Resets the display to 80-by-25 mode. |
| disp_scroll | Scrolls the screen up. |
| disp_set43 | Sets the display to 80-by-43 EGA text mode (80-by-50 VGA). |
| disp_setattr | Sets display attributes for characters. |
| disp_setcursortype | Modifies cursor appearance. |
| disp_setmode | Sets video mode. |
| disp_showcursor | Restores previously hidden cursor. |
| disp_startstand | Prints characters in reverse video. |
| disp_usebios | Sets up to write to the screen. |
Overview
The disp functions are meant to provide high speed access to the text mode video buffer in a way that provides great control while being portable from DOS16 to DOSX and even to Win32 console programs.The idea is to use disp_open() to open the display, perform the I/O to the display, and then disp_close() it. All writes to the display are done with disp functions, not functions that write to stdout.
The screen cells are addressed by row and column. (0,0) addresses the upper left cell, and (disp_numrows - 1, disp_numcols - 1) addresses the lower right cell.
A simple hello world program would be:
#include <disp.h>
int main()
{
disp_open();
disp_printf("hello world!\r\n");
disp_close();
return 0;
}
disp_close
- Prototype
- void disp_close();
- Description
- Flushes output and closes the disp package opened with disp_open().
disp_box
- Prototype
- void disp_box(int type, int attr, unsigned row, unsigned col, unsigned brow, unsigned bcol);
- Description
-
Draws a box of border type with attribute attr starting at
top left (row,col) and finishing at bottom right (brow,bcol).
Values for type are:
Value Description 0 double line border 1 single line border 2 solid line border 3 double horizontal, single vertical 4 single horizontal, double vertical
disp_eeol
- Prototype
- void disp_eeol();
- Description
- Erase from current cursor position to end of the line.
disp_eeop
- Prototype
- void disp_eeop();
- Description
- Erase from current cursor position to end of the screen.
- Example
-
To clear the screen:
#include <disp.h> int main() { disp_open(); disp_move(0,0); disp_eeop(); disp_close(); return 0; }
disp_endstand
- Prototype
- void disp_endstand();
- Description
- Reverts to normal after disp_startstand() set the attribute to reverse video mode.
disp_fillbox
- Prototype
- void disp_fillbox(unsigned attchar, unsigned trow, unsigned lcol, unsigned brow, unsigned rcol);
- Description
- Fills box with attchar. Useful for clearing rectangular areas of the screen.
disp_flush
- Prototype
- void disp_flush();
- Description
- Flushes all output and brings the screen up to date. Call this before, for example, requesting input from the user to be sure the screen is updated. This allows implementations of disp to use buffering for speed.
disp_getmode
- Prototype
- int disp_getmode();
- Description
- Gets the current video mode.
- Return Value
- Returns the current video mode.
disp_hidecursor
- Prototype
- void disp_hidecursor();
- Description
- Hides the cursor. These calls can be nested, and only when an equal number of disp_showcursor()'s have been called is the cursor shown again.
disp_getattr
- Prototype
- int disp_getattr();
void disp_setattr(int attr); - Description
-
Gets and sets the character attribute used for subsequent
character writes to the display.
The attributes can be a hex value, or one of the predefined values:
Name Description DISP_REVERSEVIDEO reverse video text DISP_NORMAL normal text DISP_UNDERLINE underlined text (mono only) DISP_NONDISPLAY black on black text The following bits can be OR'd in:
Name Description DISP_INTENSITY bold face DISP_BLINK blinking text (mono only) - Return Value
- disp_getattr() returns the current attribute.
- Example
-
This example prints "hello world!" in red.
#include <disp.h> int main() { int attr; disp_open(); // save original attribute attr = disp_getattr(); // set to red on grey disp_setattr(0x7C); disp_printf("hello world!"); // restore original attribute disp_setattr(attr); disp_printf("\r\n"); disp_close(); return 0; }
disp_move
- Prototype
- void disp_move(int row, int col);
- Description
- Sets the cursor position to (row,col). The hardware cursor may not get updated until after disp_flush() is called.
disp_open
- Prototype
- void disp_open();
- Description
-
Opens the disp package, initializes global state variables.
Close the disp package with disp_close().
The globals are read-only, and are:
Name Description disp_mono 0 if color and 1 if monochrome disp_snowycga !=0 if original IBM CGA disp_mode Current display mode. See disp_setmode(). disp_inited !=0 if disp package is open. disp_ega !=0 if IBM EGA or VGA compatible display. disp_base Segment of video display RAM (MDA=0xB000, CGA = 0xB800). disp_numrows Number of rows in the display. disp_numcols Number of columns in the display. disp_cursorrow Row of cursor position. disp_cursorcol Column of cursor position.
disp_peekbox
- Prototype
- void disp_peekbox(unsigned short *save, unsigned row, unsigned col, unsigned brow, unsigned bcol);
- Description
- Writes a block of characters to *save from the screen area described by (row,col) and (brow,bcol). Useful for rapidly transferring prebuilt screen images to the actual screen.
disp_peekw
- Prototype
- unsigned short disp_peekw(int row, int col);
- Description
- Reads screen at (row,col).
- Return Value
- Returns attribute/character at screen location (row,col).
disp_pokebox
- Prototype
- void disp_pokebox(unsigned short *save, unsigned row, unsigned col, unsigned brow, unsigned bcol);
- Description
- Writes a block of characters pointed to by save to the screen area described by (row,col) and (brow,bcol).
disp_pokew
- Prototype
- void disp_pokew(int row, int col, unsigned short attchar);
- Description
- Writes attchar into the screen at position (row,col). attchar is the attribute combined with the character to write, where attribute forms the upper byte and the character forms the lower byte.
- Example
-
This example clears the screen, and then displays all
256 characters and all 256 attributes.
#include <stdio.h> #include <disp.h> int main() { int attchar,segment,i,row,col; disp_open(); // move cursor to upper left corner disp_move(0,0); // clear screen disp_eeop(); disp_printf("\r\n0123456789ABCDEF 0123456789ABCDEF\n"); i = 0; for (row = 0; row < 16; row++) { for (col = 0; col < 16; col++) { attchar = 0x0700 + i; disp_pokew(row + 2, col, attchar); attchar = 0x0041 + i * 256; disp_pokew(row + 2, col + 18, attchar); i++; } } for (i = 0; i < 16; i++) disp_printf("\n"); disp_close(); return 0; }The output is:
disp_printf
- Prototype
- int disp_printf(char *format, ...);
- Description
- Works just like printf(), except that characters are output via disp_putc() rather than to stdout. The characters are written to the current cursor position, and the current cursor position is updated. Note that both a \n and a \r are needed to advance to the beginning of the next line, not just a \n.
- Return Value
- Returns the number of characters written.
- Example
-
This example prints "hello world!"
#include <disp.h> int main() { disp_open(); disp_printf("hello world!\r\n"); disp_close(); return 0; }
disp_putc
- Prototype
- int disp_putc(int c);
- Description
-
Writes the current character to the display using
the current attribute.
The following special characters are recognized:
Character Action 0x07 rings bell 0x08 backspace 0x09 advance to next tab stop (8 column tabs) 0x0A linefeed, advance to next line. Scroll if at bottom. 0x0B vertical tab, same as linefeed. 0x0C form feed, same as linefeed. 0x0D carriage return 0x7F del; ignored If the cursor reaches the right edge of the display, if disp_nowrap is 0, it just stays there. If it is 1, the cursor is advanced to the beginning of the next line.
- Return Value
- Returns c if successful, EOF on error.
disp_puts
- Prototype
- void disp_puts(const char *string);
- Description
- Writes all the characters in string to the screen using disp_putc().
disp_reset43
- Prototype
- void disp_reset43();
- Description
- Resets the display mode set by disp_set43() back to 80 by 25 mode. Do not use in between disp_open() and disp_close().
disp_scroll
- Prototype
- void disp_scroll(int lines, unsigned ulrow, unsigned ulcol, unsigned lrrow, unsigned lrcol, unsigned attr);
- Description
-
Scrolls the screen up.
Parameter Description lines number of lines to scroll; negative means scroll down ulrow upper left row of area to scroll ulcol upper left column of area to scroll lrrow lower right row of area to scroll lrcol lower right column of area to scroll attr video attribute to use on uncovered areas
disp_set43
- Prototype
- void disp_set43();
- Description
- Sets display mode to 80 by 43 EGA text mode. Should not be used while disp package is open. Must have an EGA or VGA for this to work. The actual resulting number of lines is written into disp_numrows and may not be 43.
disp_setcursortype
- Prototype
- void disp_setcursortype(int type);
- Description
-
Sets the cursor starting and ending line.
type is defined as (startline*256+endline).
The DOS default cursor types are:
Mode Start End type monochrome 11 12 ((11*256)+12) color 6 7 ((6*256)+7) Or, the following predefined cursor types can be used:
Name Description DISP_CURSORBLOCK block cursor DISP_CURSORHALF half height cursor DISP_CURSORUL underline cursor
disp_setmode
- Prototype
- void disp_setmode(unsigned char mode);
- Description
-
Sets the BIOS video mode to mode. Use before
calling disp_open().
Common video modes are:
Mode Size Display Card 0 40 x 25 B/W text CGA/EGA 1 40 x 25 color text CGA/EGA 2 80 x 25 B/W text CGA/EGA 3 80 x 25 color text CGA/EGA 4 320 x 200 color graphics CGA/EGA 5 320 x 200 B/W graphics CGA/EGA 6 640 x 200 color graphics CGA/EGA 7 80 x 25 B/W text MDA / EGA with mono display 0xD 320 x 200 16 color EGA 0xE 640 x 200 16 color EGA 0xF 640 x 350 4 color EGA with mono display 0x10 640 x 350 16 color EGA
disp_showcursor
- Prototype
- void disp_showcursor();
- Description
- Shows cursor again after it was hidden with disp_hidecursor().
disp_startstand
- Prototype
- void disp_startstand();
- Description
- Sets the attribute for subseqent writes to the screen to be reverse video. The effect is set back to normal with disp_endstand().
disp_usebios
- Prototype
- void disp_usebios();
- Description
- Sets up the disp functions to write chars to the screen using the BIOS rather than writing directly to the video ram. Doing so increases portability but reduces speed. Call after disp_open().