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blitlab
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doblit.c
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C/C++ Source or Header
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1992-05-06
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2KB
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71 lines
/*
* This is the routine which actually does the hard blits. We just get
* the blitter, stuff the values, wait for it to finish, disown the
* blitter, and get out of there.
*/
#include "structures.h"
/*
* External values we use.
*/
extern struct blitregs blitregs ;
/*
* This include file includes the defines for all the blitter functions.
* It only allows use of the `blit' operations; for area fills or line
* drawing, it will need to be extended.
*
* Information gleaned from the Hardware Reference Manual.
*/
#define BLTADD (0xdff040L)
/*
* This structure contains everything we need to know.
* Do not do a structure copy into this! Instead, assign
* each field. The last field assigned must be bltsize; that
* starts up the blitter. Also note that all of these are
* write only, and you can't read them.
*/
struct bltstruct {
short con0 ;
short con1 ;
short afwm ;
short alwm ;
short cpth, cptl, bpth, bptl, apth, aptl, dpth, dptl ;
short bltsize ;
short dmy1, dmy2, dmy3 ;
short cmod, bmod, amod, dmod ;
short dmy4, dmy5, dmy6, dmy7 ;
short cdat, bdat, adat ;
} *blitter = BLTADD ;
/*
* The actual routine. After we own the blitter, we need to wait for
* it to finish.
*/
doblit() {
OwnBlitter() ;
WaitBlit() ;
blitter->con0 = blitregs.con0 ;
blitter->con1 = blitregs.con1 ;
blitter->afwm = blitregs.afwm ;
blitter->alwm = blitregs.alwm ;
blitter->apth = blitregs.pth[0] ;
blitter->bpth = blitregs.pth[1] ;
blitter->cpth = blitregs.pth[2] ;
blitter->dpth = blitregs.pth[3] ;
blitter->aptl = blitregs.ptl[0] ;
blitter->bptl = blitregs.ptl[1] ;
blitter->cptl = blitregs.ptl[2] ;
blitter->dptl = blitregs.ptl[3] ;
blitter->amod = blitregs.mod[0] ;
blitter->bmod = blitregs.mod[1] ;
blitter->cmod = blitregs.mod[2] ;
blitter->dmod = blitregs.mod[3] ;
blitter->adat = blitregs.dat[0] ;
blitter->bdat = blitregs.dat[1] ;
blitter->cdat = blitregs.dat[2] ;
/*
* Wham! It is the following assignment that starts the blitter.
*/
blitter->bltsize = blitregs.size ;
WaitBlit() ;
DisownBlitter() ;
}