Add qsort()

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1916 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 236 insertions, 0 deletions

diff --git a/nuttx/lib/lib_qsort.c b/nuttx/lib/lib_qsort.c
new file mode 100644
index 000000000..06e0d8b89
--- /dev/null
+++ b/nuttx/lib/lib_qsort.c
@@ -0,0 +1,236 @@
+/****************************************************************************
+ * lib/lib_qsort.c
+ *
+ *   Copyright (C) 2007, 2009 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <stdlib.h>
+
+/****************************************************************************
+ * Preprocessor Definitions
+ ****************************************************************************/
+
+#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)
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static inline char *med3(char *, char *, char *,
+                           int (*)(const void *, const void *));
+static inline void swapfunc(char *, char *, int, int);
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+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 ));
+}
+
+/****************************************************************************
+ * Public Function
+ ****************************************************************************/
+
+/****************************************************************************
+ * 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;
+    }
+}
+