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diff --git a/lib/unistring/array-mergesort.h b/lib/unistring/array-mergesort.h
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-/* Stable-sorting of an array using mergesort.
- Copyright (C) 2009-2016 Free Software Foundation, Inc.
- Written by Bruno Haible <bruno@clisp.org>, 2009.
-
- This program is free software: you can redistribute it and/or modify it
- under the terms of either:
-
- * the GNU Lesser General Public License as published
- by the Free Software Foundation; either version 3 of the License, or
- (at your option) any later version.
-
- or
-
- * the GNU General Public License as published by the Free
- Software Foundation; either version 2 of the License, or
- (at your option) any later version.
-
- or both in parallel, as here.
-
- This program 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 <http://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.
- 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. */
-STATIC 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
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