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Length: 5705 (0x1649)
Types: TextFile
Notes: UNIX file
Names: »graph.c«
└─⟦f27320a65⟧ Bits:30001972 Commodore 900 hard disk image with partial source code
└─⟦0a3c255ba⟧ UNIX Filesystem
└─ ⟦this⟧ »graphics/graph.c«
└─⟦f27320a65⟧ Bits:30001972 Commodore 900 hard disk image with partial source code
└─⟦2d53db1df⟧ UNIX Filesystem
└─ ⟦this⟧ »frankh/gsrc/graph.c«
└─⟦f27320a65⟧ Bits:30001972 Commodore 900 hard disk image with partial source code
└─⟦926b8033d⟧ UNIX Filesystem
└─ ⟦this⟧ »u/demo/slide/graph.c«
└─ ⟦this⟧ »u/graphics/graph.c«
/*
* Line and cont routines.
*/
/*
* The following definitions make C more amenable to a purist.
*/
#define bool int /* boolean type */
#define uint unsigned int /* short names for unsigned types */
#define ulong unsigned long
#define uchar unsigned char
#define ushort unsigned short int
#define not ! /* logical negation operator */
#define and && /* logical conjunction */
#define or || /* logical disjunction */
#define TRUE (0 == 0)
#define FALSE (not TRUE)
#define loop while (TRUE) /* loop until break */
#define EOS '\0' /* end-of-string char */
/*
* Screen hardware.
*/
#define SEG0 ((short *)0x3a000000L) /* first segment of screen ram */
#define SEG1 ((short *)0x3b000000L) /* second segment of screen ram */
#define YSPLIT 512 /* segment crossover y coordinate */
#define XMAX 1024 /* just past maximum x coordinate */
#define YMAX 800 /* just past maximum y coordinate */
#define BPW 16 /* bits per word */
/*
* Globals functions.
*/
extern void clear(), /* clear screen */
move(), /* move current position */
point(), /* draw point */
cont(), /* continue line */
line(); /* draw line */
/*
* Local data.
*/
static int curx, /* current x coordinate */
cury; /* current y coordinate */
/*
* Local functions.
*/
static void xfast(),
yfast();
/*
* Clear clears the screen.
*/
void
clear()
{
register short *p;
register uint n;
for (p=SEG0, n=(uint)YSPLIT*(XMAX/BPW); n-- != 0;)
*p++ = 0;
for (p=SEG1, n=(uint)(YMAX-YSPLIT)*(XMAX/BPW); n-- != 0;)
*p++ = 0;
}
void
clearw()
{
register short *p;
register uint n;
for(p=SEG0, n=(uint)YSPLIT*(XMAX/BPW); n-- != 0;)
*p++ = 0xffff;
for(p=SEG1, n=(uint)(YMAX-YSPLIT)*(XMAX/BPW); n-- != 0; )
*p++ = 0xffff;
}
/*
* Move changes the current position.
*/
void
move(x, y)
int x,
y;
{
curx = x;
cury = y;
}
/*
* Point simply draws a point on the screen.
*/
void
point(x, y)
register int x,
y;
{
register short *p;
curx = x;
cury = y;
if (((uint)x >= XMAX)
or ((uint)y >= YMAX))
return;
if (y < YSPLIT)
p = SEG0;
else {
y -= YSPLIT;
p = SEG1;
}
p[(uint)y*(XMAX/BPW) + x/BPW] ^= (uint)0x8000 >> (x%BPW);
}
gp(x,y)
register int x,y;
{
register short *p;
if (y < YSPLIT) p = SEG0;
else p = SEG1;
return(p[(uint)y*(XMAX/BPW) + x/BPW] & (uint)0x8000 >> (x%BPW));
}
sp(x,y,pl)
register int x,y,pl;
{
register short *p;
if (y < YSPLIT) p = SEG0;
else p = SEG1;
if(pl)
p[(uint)y*(XMAX/BPW) + x/BPW] |= (uint)0x8000 >> (x%BPW);
else
p[(uint)y*(XMAX/BPW) + x/BPW] &= ~((uint)0x8000 >> (x%BPW));
}
/*
* Cont simply draws a line from the current position to its argument.
*/
void
cont(x, y)
int x,
y;
{
line(curx, cury, x, y);
}
/*
* Line is used to produce the points that are needed to fill in
* a line between two given end-points. It calls the routine
* `point' to actually place the points into an object.
*/
void
line(x, y, xf, yf)
int x,
y,
xf,
yf;
{
register int dx,
dy;
long e;
curx = xf;
cury = yf;
dx = xf - x;
dy = yf - y;
e = (long)yf*x - (long)y*xf;
if (dy >= 0) {
if ((y >= YMAX)
or (yf < 0))
return;
if (y < 0) {
x = e / dy;
y = 0;
}
if (yf >= YMAX) {
xf = ((long)(YMAX-1)*dx + e) / dy;
yf = YMAX - 1;
}
} else {
if ((yf >= YMAX)
or (y < 0))
return;
if (yf < 0) {
xf = e / dy;
yf = 0;
}
if (y >= YMAX) {
x = ((long)(YMAX-1)*dx + e) / dy;
y = YMAX - 1;
}
}
e = (long)xf*y - (long)x*yf;
if (dx > 0) {
if ((x >= XMAX)
or (xf < 0))
return;
if (x < 0) {
y = e / dx;
x = 0;
}
if (xf >= XMAX) {
yf = ((long)(XMAX-1)*dy + e) / dx;
xf = XMAX - 1;
}
if (dy > 0)
if (dx >= dy)
xfast(x, y, xf, yf);
else
yfast(x, y, xf, yf);
else
if (dx >= -dy)
xfast(x, y, xf, yf);
else
yfast(xf, yf, x, y);
} else {
if ((xf >= XMAX)
or (x < 0))
return;
if (xf < 0) {
yf = e / dx;
xf = 0;
}
if (x >= XMAX) {
y = ((long)(XMAX-1)*dy + e) / dx;
x = XMAX - 1;
}
if (dy > 0)
if (-dx >= dy)
xfast(xf, yf, x, y);
else
yfast(x, y, xf, yf);
else
if (-dx >= -dy)
xfast(xf, yf, x, y);
else
yfast(xf, yf, x, y);
}
}
static void
xfast(x, y, xf, yf)
register int x,
y;
int xf,
yf;
{
register short *vp;
register int rem;
register uint bit;
int dx,
dy,
ystep;
dx = xf - x;
dy = yf - y;
ystep = 1;
if (dy < 0) {
dy = -dy;
ystep = -1;
}
rem = dx/2;
if (y < YSPLIT)
vp = SEG0 + y*(XMAX/BPW) + x/BPW;
else
vp = SEG1 + (y-YSPLIT)*(XMAX/BPW) + x/BPW;
bit = (uint)0x8000 >> (x%BPW);
loop {
*vp ^= bit;
if (++x > xf)
break;
bit >>= 1;
if (bit == 0) {
bit = 0x8000;
++vp;
}
if ((rem -= dy) < 0) {
rem += dx;
y += ystep;
if (ystep > 0)
if (y == YSPLIT)
vp = SEG1 + y*(XMAX/BPW) + x/BPW;
else
vp += XMAX/BPW;
else
if (y == YSPLIT-1)
vp = SEG0+(y-YSPLIT)*(XMAX/BPW)+x/BPW;
else
vp -= XMAX/BPW;
}
}
}
static void
yfast(x, y, xf, yf)
register int x,
y;
int xf,
yf;
{
register short *vp;
register int rem;
register uint bit;
int dx,
dy,
xstep;
dx = xf - x;
dy = yf - y;
xstep = 1;
if (dx < 0) {
dx = -dx;
xstep = -1;
}
rem = dy/2;
if (y < YSPLIT)
vp = SEG0 + y*(XMAX/BPW) + x/BPW;
else
vp = SEG1 + (y-YSPLIT)*(XMAX/BPW) + x/BPW;
bit = (uint)0x8000 >> (x%BPW);
loop {
*vp ^= bit;
if (++y > yf)
break;
if (y == YSPLIT)
vp = SEG1 + y*(XMAX/BPW) + x/BPW;
else
vp += XMAX/BPW;
if ((rem -= dx) < 0) {
rem += dy;
x += xstep;
if (xstep > 0) {
bit >>= 1;
if (bit == 0) {
bit = 0x8000;
++vp;
}
} else {
bit <<= 1;
if (bit == 0) {
bit = 1;
--vp;
}
}
}
}
}