33 lines
975 B
C++
33 lines
975 B
C++
|
#include <graphics.h>
|
||
|
|
|
||
|
|
/* Set the screen to graphics mode. */
|
||
|
|
/* If the screen is set to monochrome, test whether it is a hercules */
|
||
|
|
/* graphics card. If 32k of screen memory exists, assume */
|
||
|
|
/* that the monochrome board is herules compatable. */
|
||
|
|
|
||
|
|
int screen(int oldmode, int dfltmode)
|
||
|
|
{
|
||
|
|
int mode = -1;
|
||
|
|
char far *memory, far *FP_SET();
|
||
|
|
char mem;
|
||
|
|
if (oldmode == MONOCHROME) {
|
||
|
|
/* check for hercules graphics card */
|
||
|
|
memory = FP_SET(0xb000,0x7ffe); /* check for extra screen memory */
|
||
|
|
mem = *memory; /* save current contents */
|
||
|
|
*memory = 0x55; /* store and check each bit as both 1 and 0 */
|
||
|
|
if (*memory == 0x55) {
|
||
|
|
*memory = 0xAA;
|
||
|
|
if (*memory == 0xAA) {
|
||
|
|
mode = HERCMODE;
|
||
|
|
setvmode(HERCMODE);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
*memory = mem; /* restore original value */
|
||
|
|
}
|
||
|
|
else {
|
||
|
|
if ((mode = setvmode(dfltmode)) != dfltmode) mode = -1;
|
||
|
|
}
|
||
|
|
return mode;
|
||
|
|
}
|
||
|
|
|