From: "David Mitchell" <dmitchell AT inet DOT net DOT nz>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Virtual Screens
Date: Fri, 2 Jul 1999 17:20:39 +1200
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

This is how I do it.
Note: This code can be very much optimised! And the putPixel method is
missing the clipping code.

char vscreen[64000];
char *scrptr;

void putPixel(int x, int y, char color) {
    int offs;

    offs = 320*y + x;

    vscreen[offs] = color;
}

void flip(void) {
    memcpy(scrptr, virt, 64000);            // #include <mem.h>
}

int main(void) {
    .
    .
    .
    __djgpp_nearptr_enable();                    // #include <sys/nearptr.h>
for this.
    scrptr = (char*) (__djgpp_conventional_base + 0xa0000);    // note 4
zeros because of

// pmode
    .
    .
    .
}

David.

PS the flip takes less than 1ms on a P200