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/* sierpin.t */
#define PPIFBUF 0xf010 /* address of ptr to IFBUF */
#define PSET 2 /* use this plot option */
struct IFBUF
{
char ERR;
char COMMAND;
char COLOR;
char PLOTOPTION;
int LINESTYLE;
int X1;
int Y1;
int X2;
int Y2;
char BFFLAG;
};
#define H0 512 /* square size */
#define XOFFS 80 /* offset to centre square */
#define XNUM 15 /* scale 512 * 15/16 = 480 */
#define XDENOM 16
#define YNUM 25 /* scale 512 * 25/64 = 200 */
#define YDENOM 64 /* to give max height, dot ratio 480/200 = 2.4 */
struct IFBUF *pifbuf;
int h, x, y;
main()
{
struct IFBUF **ppifbuf; /* required since no casts */
int i, x0, y0;
char color;
pifbuf = *(ppifbuf = PPIFBUF); /* pifbuf = *(struct IFBUF **)PPIFBUF; */
pifbuf->PLOTOPTION = PSET;
pifbuf->LINESTYLE = /* normal */
pifbuf->COMMAND = /* ?? */
pifbuf->BFFLAG = 0; /* not a box */
color = i = 0;
x0 = 2 * (h = H0/4);
y0 = 3 * (H0/4);
while ( h > 1 )
{
++i;
if ( ++color > 7 )
color = 1;
pifbuf->COLOR = color;
x = x0 -= h;
y = y0 += h /= 2;
glocate();
a( i ); x += h; y -= h; plot();
b( i ); x -= h; y -= h; plot();
c( i ); x -= h; y += h; plot();
d( i ); x += h; y += h; plot();
}
}
a( i )
int i;
{
if ( --i >= 0 )
{
a( i ); x += h; y -=h; plot();
b( i ); x += 2*h; plot();
d( i ); x += h; y += h; plot();
a( i );
}
}
b( i )
int i;
{
if ( --i >= 0 )
{
b( i ); x -= h; y -=h; plot();
c( i ); y -= 2*h; plot();
a( i ); x += h; y -= h; plot();
b( i );
}
}
c( i )
int i;
{
if ( --i >= 0 )
{
c( i ); x -= h; y +=h; plot();
d( i ); x -= 2*h; plot();
b( i ); x -= h; y -= h; plot();
c( i );
}
}
d( i )
int i;
{
if ( --i >= 0 )
{
d( i ); x += h; y +=h; plot();
a( i ); y += 2*h; plot();
c( i ); x -= h; y += h; plot();
d( i );
}
}
glocate()
{
pifbuf->X2 = x - x * (XDENOM - XNUM) / XDENOM + XOFFS;
pifbuf->Y2 = (y * YNUM) / YDENOM;
}
plot()
{
pifbuf->X1 = pifbuf->X2;
pifbuf->Y1 = pifbuf->Y2;
glocate();
#asm
SWI2
FDB $4201 call LINEMA
#endasm
}
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