/* Copyright (C) 2011 by Valentin Ochs
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
/* Minor changes by Rich Felker for integration in musl, 2011-04-27. */
/* Smoothsort, an adaptive variant of Heapsort. Memory usage: O(1).
Run time: Worst case O(n log n), close to O(n) in the mostly-sorted case. */
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include "atomic.h"
#define ntz(x) a_ctz_l((x))
typedef int (*cmpfun)(const void *, const void *);
static inline int pntz(size_t p[2]) {
int r = ntz(p[0] - 1);
if(r != 0 || (r = 8*sizeof(size_t) + ntz(p[1])) != 8*sizeof(size_t)) {
return r;
}
return 0;
}
static void cycle(size_t width, unsigned char* ar[], int n)
{
unsigned char tmp[256];
size_t l;
int i;
if(n < 2) {
return;
}
ar[n] = tmp;
while(width) {
l = sizeof(tmp) < width ? sizeof(tmp) : width;
memcpy(ar[n], ar[0], l);
for(i = 0; i < n; i++) {
memcpy(ar[i], ar[i + 1], l);
ar[i] += l;
}
width -= l;
}
}
/* shl() and shr() need n > 0 */
static inline void shl(size_t p[2], int n)
{
if(n >= 8 * sizeof(size_t)) {
n -= 8 * sizeof(size_t);
p[1] = p[0];
p[0] = 0;
}
p[1] <<= n;
p[1] |= p[0] >> (sizeof(size_t) * 8 - n);
p[0] <<= n;
}
static inline void shr(size_t p[2], int n)
{
if(n >= 8 * sizeof(size_t)) {
n -= 8 * sizeof(size_t);
p[0] = p[1];
p[1] = 0;
}
p[0] >>= n;
p[0] |= p[1] << (sizeof(size_t) * 8 - n);
p[1] >>= n;
}
static void sift(unsigned char *head, size_t width, cmpfun cmp, int pshift, size_t lp[])
{
unsigned char *rt, *lf;
unsigned char *ar[14 * sizeof(size_t) + 1];
int i = 1;
ar[0] = head;
while(pshift > 1) {
rt = head - width;
lf = head - width - lp[pshift - 2];
if((*cmp)(ar[0], lf) >= 0 && (*cmp)(ar[0], rt) >= 0) {
break;
}
if((*cmp)(lf, rt) >= 0) {
ar[i++] = lf;
head = lf;
pshift -= 1;
} else {
ar[i++] = rt;
head = rt;
pshift -= 2;
}
}
cycle(width, ar, i);
}
static void trinkle(unsigned char *head, size_t width, cmpfun cmp, size_t pp[2], int pshift, int trusty, size_t lp[])
{
unsigned char *stepson,
*rt, *lf;
size_t p[2];
unsigned char *ar[14 * sizeof(size_t) + 1];
int i = 1;
int trail;
p[0] = pp[0];
p[1] = pp[1];
ar[0] = head;
while(p[0] != 1 || p[1] != 0) {
stepson = head - lp[pshift];
if((*cmp)(stepson, ar[0]) <= 0) {
break;
}
if(!trusty && pshift > 1) {
rt = head - width;
lf = head - width - lp[pshift - 2];
if((*cmp)(rt, stepson) >= 0 || (*cmp)(lf, stepson) >= 0) {
break;
}
}
ar[i++] = stepson;
head = stepson;
trail = pntz(p);
shr(p, trail);
pshift += trail;
trusty = 0;
}
if(!trusty) {
cycle(width, ar, i);
sift(head, width, cmp, pshift, lp);
}
}
void qsort(void *base, size_t nel, size_t width, cmpfun cmp)
{
size_t lp[12*sizeof(size_t)];
size_t i, size = width * nel;
unsigned char *head, *high;
size_t p[2] = {1, 0};
int pshift = 1;
int trail;
if (!size) return;
head = base;
high = head + size - width;
/* Precompute Leonardo numbers, scaled by element width */
for(lp[0]=lp[1]=width, i=2; (lp[i]=lp[i-2]+lp[i-1]+width) < size; i++);
while(head < high) {
if((p[0] & 3) == 3) {
sift(head, width, cmp, pshift, lp);
shr(p, 2);
pshift += 2;
} else {
if(lp[pshift - 1] >= high - head) {
trinkle(head, width, cmp, p, pshift, 0, lp);
} else {
sift(head, width, cmp, pshift, lp);
}
if(pshift == 1) {
shl(p, 1);
pshift = 0;
} else {
shl(p, pshift - 1);
pshift = 1;
}
}
p[0] |= 1;
head += width;
}
trinkle(head, width, cmp, p, pshift, 0, lp);
while(pshift != 1 || p[0] != 1 || p[1] != 0) {
if(pshift <= 1) {
trail = pntz(p);
shr(p, trail);
pshift += trail;
} else {
shl(p, 2);
pshift -= 2;
p[0] ^= 7;
shr(p, 1);
trinkle(head - lp[pshift] - width, width, cmp, p, pshift + 1, 1, lp);
shl(p, 1);
p[0] |= 1;
trinkle(head - width, width, cmp, p, pshift, 1, lp);
}
head -= width;
}
}
