/**
* In linear time, group the sub-array ar[left, right) around a pivot
* element ar[right] by storing pivot into its proper location,
* store, within the sub-array (whose location is returned by this
* function) and ensuring that all ar[left,store) <= pivot and all
* ar[store+1,right) > pivot.
*
* ASSUMES THAT pivot value is already placed in ar[right] and that
* ar[left] <= ar[mid] <= ar[right].
*
* @param ar array of elements to be sorted.
* @param left lower bound index position (inclusive)
* @param right upper bound index position (exclusive)
* @return location of the pivot index properly positioned.
*/
void *partition (void *const pbase, size_t n, size_t s,
int(*cmp)(const void *,const void *)) {
void *store = (void*)((char*)pbase+(n-1)*s);
void *left = (void*)((char*)pbase+s);
void *right = (void*)((char*)store-s);
do {
while (cmp(left,store) < 0) { left += s; ADD_COMP; }
while (cmp(store,right) < 0) { right -= s; ADD_COMP; }
ADD_COMP;
ADD_COMP;
if (left < right) {
ADD_COMP;
swapcode(s,left,right);
left += s;
right -= s;
} else if (left == right) {
ADD_COMP;
ADD_COMP;
break;
} else {
ADD_COMP;
ADD_COMP;
}
} while (left <= right);
swapcode(s, left, store);
return left;
}
static inline void
swapfunc(char *a, char *b, size_t n, int swaptype)
{
if (swaptype <= 1)
swapcode(PORT_LONG, a, b, n)
else
swapcode(char, a, b, n)
}
void clipline(dcpt winmin,dcpt winmax,wcpt2 p1,wcpt2 p2)
{
unsigned char encode(wcpt2,dcpt,dcpt);
unsigned char code1,code2;
int done = 0 , draw = 0;
float m;
void swapcode(unsigned char *c1,unsigned char *c2);
void swappts(wcpt2 *p1,wcpt2 *p2);
while(!done)
{
code1 = encode(p1,winmin,winmax);
code2 = encode(p2,winmin,winmax);
if(ACCEPT(code1,code2))
{
draw = 1;
done = 1;
}
else if(REJECT(code1,code2))
done = 1;
else if(INSIDE(code1))
{
swappts(&p1,&p2);
swapcode(&code1,&code2);
}
if(code1 & LEFT_EDGE)
{
p1.y += (winmin.x - p1.x) * (p2.y - p1.y) / (p2.x - p1.x);
p1.x = winmin.x;
}
else if(code1 & RIGHT_EDGE)
{
p1.y += (winmax.x - p1.x) * (p2.y - p1.y) / (p2.x - p1.x);
p1.x = winmax.x;
}
else if(code1 & TOP_EDGE)
{
if(p2.x != p1.x)
p1.x += (winmin.y - p1.y) * (p2.x - p1.x) / (p2.y - p1.y);
p1.y = winmin.y;
}
else if(code1 & BOTTOM_EDGE)
{
if(p2.x != p1.x)
p1.x += (winmax.y - p1.y) * (p2.x - p1.x) / (p2.y - p1.y);
p1.y = winmax.y;
}
}
if(draw)
{
setcolor(5);
line(p1.x,p1.y,p2.x,p2.y);
}
}