From:	"Johan Venter" <jventer AT writeme DOT com>
Newsgroups:	comp.os.msdos.djgpp
References:	<Pine DOT SUN DOT 3 DOT 91 DOT 991021170208 DOT 4001C-100000 AT is> <380EF520 DOT C2FAE759 AT connect DOT ab DOT ca>
Subject:	Re: Plague of the slow 'blit' routine :)
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Date:	Fri, 22 Oct 1999 11:18:24 +1000
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To:	djgpp AT delorie DOT com
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Tom Fjellstrom <tomcf AT connect DOT ab DOT ca> wrote in message
news:380EF520 DOT C2FAE759 AT connect DOT ab DOT ca...
> The only way I have thought of determining that a bitmap is in video memory
> is too add a variable to the bitmap struct when creating it to indicate
> whether
> or not it is in video memory. If that is the only safe way of doing it I
> guess i'll have to.

A suggestion if I may:

Do you have a global 'screen' bitmap which always contains a pointer to the
video memory? If so, try something like this:

void blit(BITMAP *src, BITMAP *dest, int from_x, int from_y, int to_x, int to_y)
{

  int source_address = src->dat + (from_y*src->w+from_x);
  int dest_address =  dest->dat + (to_y*dest->w+to_x);

  /* maybe add some clipping here */

  if (dest->dat == screen->dat) {
        /* DO A FAR POINTER BLIT TO SCREEN */
  }
  else {
       /* DO A memcpy */
  }
}


Note:

1. Code written very fast.
2. Code untested.
3. Not even sure code will compile.

Hopefully you get the point though,

--
Johan Venter
ICQ 3643877 - jventer AT writeme DOT com
The TPU DJGPP Interest Group - http://surf.to/djgppig
The RSXNTDJ 1.5 HOWTO - http://surf.to/rsxntdj

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