Adding upstream version 1.21.3.upstream/1.21.3upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 281 insertions, 0 deletions

diff --git a/lib/array-mergesort.h b/lib/array-mergesort.h
new file mode 100644
index 0000000..c70dc73
--- /dev/null
+++ b/lib/array-mergesort.h
@@ -0,0 +1,281 @@
+/* Stable-sorting of an array using mergesort.
+   Copyright (C) 2009-2022 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2009.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   This file is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* This file implements stable sorting of an array, using the mergesort
+   algorithm.
+   Worst-case running time for an array of length N is O(N log N).
+   Unlike the mpsort module, the algorithm here attempts to minimize not
+   only the number of comparisons, but also the number of copying operations.
+
+   Before including this file, you need to define
+     ELEMENT      The type of every array element.
+     COMPARE      A two-argument macro that takes two 'const ELEMENT *'
+                  pointers and returns a negative, zero, or positive 'int'
+                  value if the element pointed to by the first argument is,
+                  respectively, less, equal, or greater than the element
+                  pointed to by the second argument.
+     STATIC       The storage class of the functions being defined.
+     STATIC_FROMTO  (Optional.) Overrides STATIC for the 'merge_sort_fromto'
+                    function.
+   Before including this file, you also need to include:
+     #include <stddef.h>
+ */
+
+/* Merge the sorted arrays src1[0..n1-1] and src2[0..n2-1] into
+   dst[0..n1+n2-1].  In case of ambiguity, put the elements of src1
+   before the elements of src2.
+   n1 and n2 must be > 0.
+   The arrays src1 and src2 must not overlap the dst array, except that
+   src1 may be dst[n2..n1+n2-1], or src2 may be dst[n1..n1+n2-1].  */
+static void
+merge (const ELEMENT *src1, size_t n1,
+       const ELEMENT *src2, size_t n2,
+       ELEMENT *dst)
+{
+  for (;;) /* while (n1 > 0 && n2 > 0) */
+    {
+      if (COMPARE (src1, src2) <= 0)
+        {
+          *dst++ = *src1++;
+          n1--;
+          if (n1 == 0)
+            break;
+        }
+      else
+        {
+          *dst++ = *src2++;
+          n2--;
+          if (n2 == 0)
+            break;
+        }
+    }
+  /* Here n1 == 0 || n2 == 0 but also n1 > 0 || n2 > 0.  */
+  if (n1 > 0)
+    {
+      if (dst != src1)
+        do
+          {
+            *dst++ = *src1++;
+            n1--;
+          }
+        while (n1 > 0);
+    }
+  else /* n2 > 0 */
+    {
+      if (dst != src2)
+        do
+          {
+            *dst++ = *src2++;
+            n2--;
+          }
+        while (n2 > 0);
+    }
+}
+
+/* Sort src[0..n-1] into dst[0..n-1], using tmp[0..n/2-1] as temporary
+   (scratch) storage.
+   The arrays src, dst, tmp must not overlap.  */
+#ifdef STATIC_FROMTO
+STATIC_FROMTO
+#else
+STATIC
+#endif
+void
+merge_sort_fromto (const ELEMENT *src, ELEMENT *dst, size_t n, ELEMENT *tmp)
+{
+  switch (n)
+    {
+    case 0:
+      return;
+    case 1:
+      /* Nothing to do.  */
+      dst[0] = src[0];
+      return;
+    case 2:
+      /* Trivial case.  */
+      if (COMPARE (&src[0], &src[1]) <= 0)
+        {
+          /* src[0] <= src[1] */
+          dst[0] = src[0];
+          dst[1] = src[1];
+        }
+      else
+        {
+          dst[0] = src[1];
+          dst[1] = src[0];
+        }
+      break;
+    case 3:
+      /* Simple case.  */
+      if (COMPARE (&src[0], &src[1]) <= 0)
+        {
+          if (COMPARE (&src[1], &src[2]) <= 0)
+            {
+              /* src[0] <= src[1] <= src[2] */
+              dst[0] = src[0];
+              dst[1] = src[1];
+              dst[2] = src[2];
+            }
+          else if (COMPARE (&src[0], &src[2]) <= 0)
+            {
+              /* src[0] <= src[2] < src[1] */
+              dst[0] = src[0];
+              dst[1] = src[2];
+              dst[2] = src[1];
+            }
+          else
+            {
+              /* src[2] < src[0] <= src[1] */
+              dst[0] = src[2];
+              dst[1] = src[0];
+              dst[2] = src[1];
+            }
+        }
+      else
+        {
+          if (COMPARE (&src[0], &src[2]) <= 0)
+            {
+              /* src[1] < src[0] <= src[2] */
+              dst[0] = src[1];
+              dst[1] = src[0];
+              dst[2] = src[2];
+            }
+          else if (COMPARE (&src[1], &src[2]) <= 0)
+            {
+              /* src[1] <= src[2] < src[0] */
+              dst[0] = src[1];
+              dst[1] = src[2];
+              dst[2] = src[0];
+            }
+          else
+            {
+              /* src[2] < src[1] < src[0] */
+              dst[0] = src[2];
+              dst[1] = src[1];
+              dst[2] = src[0];
+            }
+        }
+      break;
+    default:
+      {
+        size_t n1 = n / 2;
+        size_t n2 = (n + 1) / 2;
+        /* Note: n1 + n2 = n, n1 <= n2.  */
+        /* Sort src[n1..n-1] into dst[n1..n-1], scratching tmp[0..n2/2-1].  */
+        merge_sort_fromto (src + n1, dst + n1, n2, tmp);
+        /* Sort src[0..n1-1] into tmp[0..n1-1], scratching dst[0..n1-1].  */
+        merge_sort_fromto (src, tmp, n1, dst);
+        /* Merge the two half results.  */
+        merge (tmp, n1, dst + n1, n2, dst);
+      }
+      break;
+    }
+}
+
+/* Sort src[0..n-1], using tmp[0..n-1] as temporary (scratch) storage.
+   The arrays src, tmp must not overlap. */
+STATIC void
+merge_sort_inplace (ELEMENT *src, size_t n, ELEMENT *tmp)
+{
+  switch (n)
+    {
+    case 0:
+    case 1:
+      /* Nothing to do.  */
+      return;
+    case 2:
+      /* Trivial case.  */
+      if (COMPARE (&src[0], &src[1]) <= 0)
+        {
+          /* src[0] <= src[1] */
+        }
+      else
+        {
+          ELEMENT t = src[0];
+          src[0] = src[1];
+          src[1] = t;
+        }
+      break;
+    case 3:
+      /* Simple case.  */
+      if (COMPARE (&src[0], &src[1]) <= 0)
+        {
+          if (COMPARE (&src[1], &src[2]) <= 0)
+            {
+              /* src[0] <= src[1] <= src[2] */
+            }
+          else if (COMPARE (&src[0], &src[2]) <= 0)
+            {
+              /* src[0] <= src[2] < src[1] */
+              ELEMENT t = src[1];
+              src[1] = src[2];
+              src[2] = t;
+            }
+          else
+            {
+              /* src[2] < src[0] <= src[1] */
+              ELEMENT t = src[0];
+              src[0] = src[2];
+              src[2] = src[1];
+              src[1] = t;
+            }
+        }
+      else
+        {
+          if (COMPARE (&src[0], &src[2]) <= 0)
+            {
+              /* src[1] < src[0] <= src[2] */
+              ELEMENT t = src[0];
+              src[0] = src[1];
+              src[1] = t;
+            }
+          else if (COMPARE (&src[1], &src[2]) <= 0)
+            {
+              /* src[1] <= src[2] < src[0] */
+              ELEMENT t = src[0];
+              src[0] = src[1];
+              src[1] = src[2];
+              src[2] = t;
+            }
+          else
+            {
+              /* src[2] < src[1] < src[0] */
+              ELEMENT t = src[0];
+              src[0] = src[2];
+              src[2] = t;
+            }
+        }
+      break;
+    default:
+      {
+        size_t n1 = n / 2;
+        size_t n2 = (n + 1) / 2;
+        /* Note: n1 + n2 = n, n1 <= n2.  */
+        /* Sort src[n1..n-1], scratching tmp[0..n2-1].  */
+        merge_sort_inplace (src + n1, n2, tmp);
+        /* Sort src[0..n1-1] into tmp[0..n1-1], scratching tmp[n1..2*n1-1].  */
+        merge_sort_fromto (src, tmp, n1, tmp + n1);
+        /* Merge the two half results.  */
+        merge (tmp, n1, src + n1, n2, src);
+      }
+      break;
+    }
+}
+
+#undef ELEMENT
+#undef COMPARE
+#undef STATIC