This program is an example of using Turbo C inline assembly statements. For compilation you will need:
- Turbo C 2.01 and Turbo Assembler installed (
tcc -B plot.c) - or Borland C++ 3.1 (
bcc -B plot.c)
/****************************************************************
* *
* This program is an example of using Turbo C inline *
* assembly statements. *
* *
* The program should be compiled with the command line *
* version of Turbo C with the compile with assembly *
* flag on (tcc -B plot). *
* *
****************************************************************/
#include <stdio.h>
/* define some crt modes */
#define BW40 0
#define COLOR40 1
#define BW80 2
#define COLOR80 3
#define CGA320 4
#define CGA320CB 5
#define CGA640 6
#define MONO 7
#define EGA320 0x0D
#define EGA640 0x0E
#define EGAMono 0x0F
#define EGAFull 0x10
void set_crtmode(int mode) {
/****************************************************************
* *
* Set the crt mode with interrupt 16 function 0 *
* *
****************************************************************/
asm mov ah, 0 /* function 0, set video mode */
asm mov al, mode
asm int 16 /* call interrupt 16 */
}
void plotpixel(int x, int y, int pixel_val) {
/****************************************************************
* *
* Plot a pixel at x,y *
* *
****************************************************************/
asm mov ah, 12 /* function 12 */
asm mov al, pixel_val /* pixel attribute */
asm mov cx, x
asm mov dx, y
asm int 16 /* call interrupt 16 */
} /* plotpixel */
void draw(int _x1, int _y1, int _x2, int _y2, int attr){
/****************************************************************
* *
* Draw a line from _x1,_y1 to _x2,_y2 *
* *
****************************************************************/
int x, y, deltax, deltay, xstep, ystep, direction;
int x1, y1, x2, y2;
x = x1 = _x1;
y = y1 = _y1;
xstep = (x1 > (x2 = _x2)) ? -1 : 1;
ystep = (y1 > (y2 = _y2)) ? -1 : 1;
deltax = abs(x2 - x1);
deltay = abs(y2 - y1);
direction = (deltax == 0) ? -1 : 0;
while ( !( (x == x2) && (y == y2) ) ) {
plotpixel(x, y, attr);
if (direction < 0) {
y += ystep;
direction += deltax;
} else {
x += xstep;
direction -= deltay;
}
}
} /* draw */
void box(int x1, int y1, int x2, int y2, int attr){
/****************************************************************
* *
* Draw a box with corners x1,y1 & x2,y2 *
* *
****************************************************************/
int i;
/* draw top and bottom */
for (i = x1 ; i <= x2 ; i++) {
plotpixel(i,y1,attr);
plotpixel(i,y2,attr);
}
/* draw sides */
for (i = y1 ; i <= y2 ; i++) {
plotpixel(x1,i,attr);
plotpixel(x2,i,attr);
}
}
main(){
/* turn on CGA 640 X 200 */
set_crtmode(CGA640);
printf("This is an example of using 640 X 200 CGA");
box(20,20,630,190,1);
draw(20,20,630,190,1);
getch();
/* turn on color text mode */
set_crtmode(COLOR80);
}