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authorChristopher Faylor <me+cygwin@cgf.cx>2000-03-25 02:14:57 +0000
committerChristopher Faylor <me+cygwin@cgf.cx>2000-03-25 02:14:57 +0000
commit57c987aa1017d17b686c47f916c9e1bf7f5e13eb (patch)
tree3bf1bae2c04c7d60e183ae8854a925bece7ec6e7 /libiberty/partition.c
parentde616bc73805a3cdbdcc657aeabc97abf71f19e9 (diff)
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* partition.c: New file.
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diff --git a/libiberty/partition.c b/libiberty/partition.c
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+/* List implentation of a partition of consecutive integers.
+ Copyright (C) 2000 Free Software Foundation, Inc.
+ Contributed by CodeSourcery, LLC.
+
+ This file is part of GNU CC.
+
+ GNU CC is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ GNU CC 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with GNU CC; see the file COPYING. If not, write to
+ the Free Software Foundation, 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#ifdef HAVE_STDLIB_H
+#include <stdlib.h>
+#endif
+
+#include "libiberty.h"
+#include "partition.h"
+
+/* Creates a partition of NUM_ELEMENTS elements. Initially each
+ element is in a class by itself. */
+
+partition
+partition_new (num_elements)
+ int num_elements;
+{
+ int e;
+
+ partition part = (partition)
+ xmalloc (sizeof (struct partition_def) +
+ (num_elements - 1) * sizeof (struct partition_elem));
+ part->num_elements = num_elements;
+ for (e = 0; e < num_elements; ++e)
+ {
+ part->elements[e].class_element = e;
+ part->elements[e].next = &(part->elements[e]);
+ part->elements[e].class_count = 1;
+ }
+
+ return part;
+}
+
+/* Freeds a partition. */
+
+void
+partition_delete (part)
+ partition part;
+{
+ free (part);
+}
+
+/* Unites the classes containing ELEM1 and ELEM2 into a single class
+ of partition PART. If ELEM1 and ELEM2 are already in the same
+ class, does nothing. Returns the canonical element of the
+ resulting union class. */
+
+int
+partition_union (part, elem1, elem2)
+ partition part;
+ int elem1;
+ int elem2;
+{
+ struct partition_elem *elements = part->elements;
+ struct partition_elem *e1;
+ struct partition_elem *e2;
+ struct partition_elem *p;
+ struct partition_elem *old_next;
+ /* The canonical element of the resulting union class. */
+ int class_element = elements[elem1].class_element;
+
+ /* If they're already in the same class, do nothing. */
+ if (class_element == elements[elem2].class_element)
+ return class_element;
+
+ /* Make sure ELEM1 is in the larger class of the two. If not, swap
+ them. This way we always scan the shorter list. */
+ if (elements[elem1].class_count < elements[elem2].class_count)
+ {
+ int temp = elem1;
+ elem1 = elem2;
+ elem2 = temp;
+ class_element = elements[elem1].class_element;
+ }
+
+ e1 = &(elements[elem1]);
+ e2 = &(elements[elem2]);
+
+ /* Keep a count of the number of elements in the list. */
+ elements[class_element].class_count
+ += elements[e2->class_element].class_count;
+
+ /* Update the class fields in elem2's class list. */
+ e2->class_element = class_element;
+ for (p = e2->next; p != e2; p = p->next)
+ p->class_element = class_element;
+
+ /* Splice ELEM2's class list into ELEM1's. These are circular
+ lists. */
+ old_next = e1->next;
+ e1->next = e2->next;
+ e2->next = old_next;
+
+ return class_element;
+}
+
+/* Compare elements ELEM1 and ELEM2 from array of integers, given a
+ pointer to each. Used to qsort such an array. */
+
+static int
+elem_compare (elem1, elem2)
+ const void *elem1;
+ const void *elem2;
+{
+ int e1 = * (int *) elem1;
+ int e2 = * (int *) elem2;
+ if (e1 < e2)
+ return -1;
+ else if (e1 > e2)
+ return 1;
+ else
+ return 0;
+}
+
+/* Prints PART to the file pointer FP. The elements of each
+ class are sorted. */
+
+void
+partition_print (part, fp)
+ partition part;
+ FILE *fp;
+{
+ char *done;
+ int num_elements = part->num_elements;
+ struct partition_elem *elements = part->elements;
+ int *class_elements;
+ int e;
+
+ /* Flag the elements we've already printed. */
+ done = (char *) xmalloc (num_elements);
+ memset (done, 0, num_elements);
+
+ /* A buffer used to sort elements in a class. */
+ class_elements = (int *) xmalloc (num_elements * sizeof (int));
+
+ fputc ('[', fp);
+ for (e = 0; e < num_elements; ++e)
+ /* If we haven't printed this element, print its entire class. */
+ if (! done[e])
+ {
+ int c = e;
+ int count = elements[elements[e].class_element].class_count;
+ int i;
+
+ /* Collect the elements in this class. */
+ for (i = 0; i < count; ++i) {
+ class_elements[i] = c;
+ done[c] = 1;
+ c = elements[c].next - elements;
+ }
+ /* Sort them. */
+ qsort ((void *) class_elements, count, sizeof (int), &elem_compare);
+ /* Print them. */
+ fputc ('(', fp);
+ for (i = 0; i < count; ++i)
+ fprintf (fp, i == 0 ? "%d" : " %d", class_elements[i]);
+ fputc (')', fp);
+ }
+ fputc (']', fp);
+
+ free (done);
+}
+