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p4pixset.c
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1993-12-06
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/**
** P4PIXSET.C
**
** Copyright (C) 1992, Csaba Biegl
** 820 Stirrup Dr, Nashville, TN, 37221
** csaba@vuse.vanderbilt.edu
**
** This file is distributed under the terms listed in the document
** "copying.cb", available from the author at the address above.
** A copy of "copying.cb" should accompany this file; if not, a copy
** should be available from where this file was obtained. This file
** may not be distributed without a verbatim copy of "copying.cb".
** You should also have received a copy of the GNU General Public
** License along with this program (it is in the file "copying");
** if not, write to the Free Software Foundation, Inc., 675 Mass Ave,
** Cambridge, MA 02139, USA.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
**/
#include "p4.h"
void _GrP4SetPixel(long addr,int color)
{
pixptr p = P_ADDRESS(CURC,addr);
int mask = 0x80 >> P_OFFSET(addr);
int opr = C_OPER(color);
int plane;
if(CURC->gc_onscreen) {
_SetVideoColor((color & 0x0f),opr);
_SetVGAWriteMask(mask);
(*p)++;
return;
}
opr <<= 1;
for(plane = 4; --plane >= 0; color >>= 1) {
switch(opr | (color & 1)) {
case C_XOR2+1:
*p ^= mask;
break;
case C_OR2+1:
case C_SET2+1:
*p |= mask;
break;
case C_AND2+0:
case C_SET2+0:
*p &= ~mask;
break;
}
p = (pixptr)((long)p + CURC->gc_planeoffset);
}
}