static void rad_sort_u(uint *from, uint *to, uint bit) {
if(!bit || to < from + 1) return;
uint *ll = from, *rr = to - 1, tmp;
while(1) {
while(ll < rr && !(*ll & bit)) ll++;
while(ll < rr && (*rr & bit)) rr--;
if(ll >= rr) break;
swap(*ll, *rr);
}
if(!(bit & *ll) && ll < to) ll++;
bit >>= 1;
rad_sort_u(from, ll, bit);
rad_sort_u(ll, to, bit);
}
/* sort signed ints: flip highest bit, sort as unsigned, flip back */
static void radix_sort(int *a, const size_t len) {
size_t i;
uint *x = (uint*) a;
each(i, len) x[i] ^= INT_MIN;
rad_sort_u(x, x + len, INT_MIN);
each(i, len) x[i] ^= INT_MIN;
}
/* sort unsigned ints */
static void rad_sort_u(uint *from, uint *to, uint bit) {
uint *ll = from, *rr = to - 1, tmp;
if (!bit || to < from + 1) {
return;
}
while (1) {
/* find left most with bit, and right most without bit, swap */
while(ll < rr && !(*ll & bit)) ll++;
while(ll < rr && (*rr & bit)) rr--;
if (ll >= rr) break;
swap(*ll, *rr);
}
if (!(bit & *ll) && ll < to) ll++;
bit >>= 1;
rad_sort_u(from, ll, bit);
rad_sort_u(ll, to, bit);
}
void radix_sort(int *a, const size_t len)
{
size_t i;
uint *x = (uint*) a;
// Flip negative signs so sorting works properly
each(i, len) x[i] ^= INT_MIN;
// Sort unsigned
rad_sort_u(x, x+len, INT_MIN);
// Flip negative signs back
each(i, len) x[i] ^= INT_MIN;
}
static inline void radix_sort_unsigned(uint *a, const size_t len) {
rad_sort_u(a, a + len, (uint) INT_MIN);
}
