--- /dev/null
+/****************************************************************************
+ * lib/stdlib/lib_qsort.c
+ *
+ * Copyright (C) 2007, 2009, 2011 Gregory Nutt. All rights reserved.
+ * Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Leveraged from:
+ *
+ * Copyright (c) 1992, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#include <stdlib.h>
+
+#define min(a, b) (a) < (b) ? a : b
+
+#define swapcode(TYPE, parmi, parmj, n) \
+ { \
+ long i = (n) / sizeof (TYPE); \
+ register TYPE *pi = (TYPE *) (parmi); \
+ register TYPE *pj = (TYPE *) (parmj); \
+ do { \
+ register TYPE t = *pi; \
+ *pi++ = *pj; \
+ *pj++ = t; \
+ } while (--i > 0); \
+ }
+
+#define SWAPINIT(a, size) \
+ swaptype = ((char *)a - (char *)0) % sizeof(long) || \
+ size % sizeof(long) ? 2 : size == sizeof(long)? 0 : 1;
+
+#define swap(a, b) \
+ if (swaptype == 0) \
+ { \
+ long t = *(long *)(a); \
+ *(long *)(a) = *(long *)(b); \
+ *(long *)(b) = t; \
+ } \
+ else \
+ { \
+ swapfunc(a, b, size, swaptype); \
+ }
+
+#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
+
+static inline void swapfunc(char *a, char *b, int n, int swaptype);
+static inline char *med3(char *a, char *b, char *c,
+ int (*compar)(const void *, const void *));
+
+static inline void swapfunc(char *a, char *b, int n, int swaptype)
+{
+ if(swaptype <= 1)
+ {
+ swapcode(long, a, b, n)
+ }
+ else
+ {
+ swapcode(char, a, b, n)
+ }
+}
+
+static inline char *med3(char *a, char *b, char *c,
+ int (*compar)(const void *, const void *))
+{
+ return compar(a, b) < 0 ?
+ (compar(b, c) < 0 ? b : (compar(a, c) < 0 ? c : a ))
+ :(compar(b, c) > 0 ? b : (compar(a, c) < 0 ? a : c ));
+}
+
+/****************************************************************************
+ * Name: qsort
+ *
+ * Description:
+ * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
+ *
+ ****************************************************************************/
+
+void qsort(void *base, size_t nmemb, size_t size,
+ int(*compar)(const void *, const void *))
+{
+ char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
+ int d, r, swaptype, swap_cnt;
+
+loop:
+ SWAPINIT(base, size);
+ swap_cnt = 0;
+ if (nmemb < 7)
+ {
+ for (pm = (char *) base + size; pm < (char *) base + nmemb * size; pm += size)
+ {
+ for (pl = pm; pl > (char *) base && compar(pl - size, pl) > 0; pl -= size)
+ {
+ swap(pl, pl - size);
+ }
+ }
+ return;
+ }
+
+ pm = (char *) base + (nmemb / 2) * size;
+ if (nmemb > 7)
+ {
+ pl = base;
+ pn = (char *) base + (nmemb - 1) * size;
+ if (nmemb > 40)
+ {
+ d = (nmemb / 8) * size;
+ pl = med3(pl, pl + d, pl + 2 * d, compar);
+ pm = med3(pm - d, pm, pm + d, compar);
+ pn = med3(pn - 2 * d, pn - d, pn, compar);
+ }
+ pm = med3(pl, pm, pn, compar);
+ }
+ swap(base, pm);
+ pa = pb = (char *) base + size;
+
+ pc = pd = (char *) base + (nmemb - 1) * size;
+ for (;;)
+ {
+ while (pb <= pc && (r = compar(pb, base)) <= 0)
+ {
+ if (r == 0)
+ {
+ swap_cnt = 1;
+ swap(pa, pb);
+ pa += size;
+ }
+ pb += size;
+ }
+ while (pb <= pc && (r = compar(pc, base)) >= 0)
+ {
+ if (r == 0)
+ {
+ swap_cnt = 1;
+ swap(pc, pd);
+ pd -= size;
+ }
+ pc -= size;
+ }
+
+ if (pb > pc)
+ {
+ break;
+ }
+
+ swap(pb, pc);
+ swap_cnt = 1;
+ pb += size;
+ pc -= size;
+ }
+
+ if (swap_cnt == 0)
+ {
+ /* Switch to insertion sort */
+
+ for (pm = (char *) base + size; pm < (char *) base + nmemb * size; pm += size)
+ {
+ for (pl = pm; pl > (char *) base && compar(pl - size, pl) > 0; pl -= size)
+ {
+ swap(pl, pl - size);
+ }
+ }
+ return;
+ }
+
+ pn = (char *) base + nmemb * size;
+ r = min(pa - (char *)base, pb - pa);
+ vecswap(base, pb - r, r);
+ r = min(pd - pc, pn - pd - size);
+ vecswap(pb, pn - r, r);
+
+ if ((r = pb - pa) > size)
+ {
+ qsort(base, r / size, size, compar);
+ }
+
+ if ((r = pd - pc) > size)
+ {
+ /* Iterate rather than recurse to save stack space */
+ base = pn - r;
+ nmemb = r / size;
+ goto loop;
+ }
+}
+
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