vppinfra: finish deprecating qsort.c

Minor change to vec_sort_with_function(...): don't depend on the qsort
implementation to deal with null, zero-long, or 1-long vectors

Type: fix

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: I7bd7b0421673d2a025363089562aa7c6266fba66

extras/deprecated/vppinfra/qsort.c

@@ -0,0 +1,269 @@
+/*
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+ * Imported into CLIB by Eliot Dresselhaus from:
+ *
+ *  This file is part of
+ *	MakeIndex - A formatter and format independent index processor
+ *
+ *  This file is public domain software donated by
+ *  Nelson Beebe (beebe@science.utah.edu).
+ *
+ *  modifications copyright (c) 2003 Cisco Systems, Inc.
+ */
+
+#include <vppinfra/clib.h>
+
+/*
+ * qsort.c: Our own version of the system qsort routine which is faster by an
+ * average of 25%, with lows and highs of 10% and 50%. The THRESHold below is
+ * the insertion sort threshold, and has been adjusted for records of size 48
+ * bytes. The MTHREShold is where we stop finding a better median.
+ */
+
+#define THRESH  4		/* threshold for insertion */
+#define MTHRESH 6		/* threshold for median */
+
+typedef struct
+{
+  word qsz;			/* size of each record */
+  word thresh;			/* THRESHold in chars */
+  word mthresh;			/* MTHRESHold in chars */
+  int (*qcmp) (const void *, const void *);	/* the comparison routine */
+} qst_t;
+
+static void qst (qst_t * q, char *base, char *max);
+
+/*
+ * qqsort: First, set up some global parameters for qst to share.
+ * Then, quicksort with qst(), and then a cleanup insertion sort ourselves.
+ * Sound simple?  It's not...
+ */
+
+void
+qsort (void *base, uword n, uword size,
+       int (*compar) (const void *, const void *))
+{
+  char *i;
+  char *j;
+  char *lo;
+  char *hi;
+  char *min;
+  char c;
+  char *max;
+  qst_t _q, *q = &_q;
+
+  if (n <= 1)
+    return;
+
+  q->qsz = size;
+  q->qcmp = compar;
+  q->thresh = q->qsz * THRESH;
+  q->mthresh = q->qsz * MTHRESH;
+  max = base + n * q->qsz;
+  if (n >= THRESH)
+    {
+      qst (q, base, max);
+      hi = base + q->thresh;
+    }
+  else
+    {
+      hi = max;
+    }
+  /*
+   * First put smallest element, which must be in the first THRESH, in the
+   * first position as a sentinel.  This is done just by searching the
+   * first THRESH elements (or the first n if n < THRESH), finding the min,
+   * and swapping it into the first position.
+   */
+  for (j = lo = base; (lo += q->qsz) < hi;)
+    {
+      if ((*compar) (j, lo) > 0)
+	j = lo;
+    }
+  if (j != base)
+    {				/* swap j into place */
+      for (i = base, hi = base + q->qsz; i < hi;)
+	{
+	  c = *j;
+	  *j++ = *i;
+	  *i++ = c;
+	}
+    }
+  /*
+   * With our sentinel in place, we now run the following hyper-fast
+   * insertion sort. For each remaining element, min, from [1] to [n-1],
+   * set hi to the index of the element AFTER which this one goes. Then, do
+   * the standard insertion sort shift on a character at a time basis for
+   * each element in the frob.
+   */
+  for (min = base; (hi = min += q->qsz) < max;)
+    {
+      while ((*q->qcmp) (hi -= q->qsz, min) > 0);
+      if ((hi += q->qsz) != min)
+	{
+	  for (lo = min + q->qsz; --lo >= min;)
+	    {
+	      c = *lo;
+	      for (i = j = lo; (j -= q->qsz) >= hi; i = j)
+		*i = *j;
+	      *i = c;
+	    }
+	}
+    }
+}
+
+
+
+/*
+ * qst: Do a quicksort.  First, find the median element, and put that one in
+ * the first place as the discriminator.  (This "median" is just the median
+ * of the first, last and middle elements).  (Using this median instead of
+ * the first element is a big win). Then, the usual partitioning/swapping,
+ * followed by moving the discriminator into the right place.  Then, figure
+ * out the sizes of the two partitions, do the smaller one recursively and the
+ * larger one via a repeat of this code.  Stopping when there are less than
+ * THRESH elements in a partition and cleaning up with an insertion sort (in
+ * our caller) is a huge win. All data swaps are done in-line, which is
+ * space-losing but time-saving. (And there are only three places where this
+ * is done).
+ */
+
+static void
+qst (qst_t * q, char *base, char *max)
+{
+  char *i;
+  char *j;
+  char *jj;
+  char *mid;
+  int ii;
+  char c;
+  char *tmp;
+  int lo;
+  int hi;
+  int qsz = q->qsz;
+
+  lo = (int) (max - base);	/* number of elements as chars */
+  do
+    {
+      /*
+       * At the top here, lo is the number of characters of elements in the
+       * current partition.  (Which should be max - base). Find the median
+       * of the first, last, and middle element and make that the middle
+       * element.  Set j to largest of first and middle.  If max is larger
+       * than that guy, then it's that guy, else compare max with loser of
+       * first and take larger.  Things are set up to prefer the middle,
+       * then the first in case of ties.
+       */
+      mid = i = base + qsz * ((unsigned) (lo / qsz) >> 1);
+      if (lo >= q->mthresh)
+	{
+	  j = ((*q->qcmp) ((jj = base), i) > 0 ? jj : i);
+	  if ((*q->qcmp) (j, (tmp = max - qsz)) > 0)
+	    {
+	      /* switch to first loser */
+	      j = (j == jj ? i : jj);
+	      if ((*q->qcmp) (j, tmp) < 0)
+		j = tmp;
+	    }
+	  if (j != i)
+	    {
+	      ii = qsz;
+	      do
+		{
+		  c = *i;
+		  *i++ = *j;
+		  *j++ = c;
+		}
+	      while (--ii);
+	    }
+	}
+      /* Semi-standard quicksort partitioning/swapping */
+      for (i = base, j = max - qsz;;)
+	{
+	  while (i < mid && (*q->qcmp) (i, mid) <= 0)
+	    i += qsz;
+	  while (j > mid)
+	    {
+	      if ((*q->qcmp) (mid, j) <= 0)
+		{
+		  j -= qsz;
+		  continue;
+		}
+	      tmp = i + qsz;	/* value of i after swap */
+	      if (i == mid)
+		{		/* j <-> mid, new mid is j */
+		  mid = jj = j;
+		}
+	      else
+		{		/* i <-> j */
+		  jj = j;
+		  j -= qsz;
+		}
+	      goto swap;
+	    }
+	  if (i == mid)
+	    {
+	      break;
+	    }
+	  else
+	    {			/* i <-> mid, new mid is i */
+	      jj = mid;
+	      tmp = mid = i;	/* value of i after swap */
+	      j -= qsz;
+	    }
+	swap:
+	  ii = qsz;
+	  do
+	    {
+	      c = *i;
+	      *i++ = *jj;
+	      *jj++ = c;
+	    }
+	  while (--ii);
+	  i = tmp;
+	}
+      /*
+       * Look at sizes of the two partitions, do the smaller one first by
+       * recursion, then do the larger one by making sure lo is its size,
+       * base and max are update correctly, and branching back. But only
+       * repeat (recursively or by branching) if the partition is of at
+       * least size THRESH.
+       */
+      i = (j = mid) + qsz;
+      if ((lo = (int) (j - base)) <= (hi = (int) (max - i)))
+	{
+	  if (lo >= q->thresh)
+	    qst (q, base, j);
+	  base = i;
+	  lo = hi;
+	}
+      else
+	{
+	  if (hi >= q->thresh)
+	    qst (q, i, max);
+	  max = j;
+	}
+    }
+  while (lo >= q->thresh);
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */