* partition.c: New file.
This commit is contained in:
Christopher Faylor
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de616bc738
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57c987aa10
185
libiberty/partition.c
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185
libiberty/partition.c
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/* List implentation of a partition of consecutive integers.
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Copyright (C) 2000 Free Software Foundation, Inc.
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Contributed by CodeSourcery, LLC.
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU CC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#ifdef HAVE_STDLIB_H
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#include <stdlib.h>
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#endif
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#include "libiberty.h"
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#include "partition.h"
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/* Creates a partition of NUM_ELEMENTS elements. Initially each
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element is in a class by itself. */
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partition
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partition_new (num_elements)
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int num_elements;
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{
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int e;
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partition part = (partition)
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xmalloc (sizeof (struct partition_def) +
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(num_elements - 1) * sizeof (struct partition_elem));
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part->num_elements = num_elements;
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for (e = 0; e < num_elements; ++e)
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{
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part->elements[e].class_element = e;
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part->elements[e].next = &(part->elements[e]);
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part->elements[e].class_count = 1;
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}
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return part;
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}
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/* Freeds a partition. */
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void
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partition_delete (part)
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partition part;
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{
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free (part);
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}
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/* Unites the classes containing ELEM1 and ELEM2 into a single class
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of partition PART. If ELEM1 and ELEM2 are already in the same
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class, does nothing. Returns the canonical element of the
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resulting union class. */
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int
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partition_union (part, elem1, elem2)
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partition part;
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int elem1;
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int elem2;
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{
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struct partition_elem *elements = part->elements;
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struct partition_elem *e1;
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struct partition_elem *e2;
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struct partition_elem *p;
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struct partition_elem *old_next;
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/* The canonical element of the resulting union class. */
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int class_element = elements[elem1].class_element;
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/* If they're already in the same class, do nothing. */
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if (class_element == elements[elem2].class_element)
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return class_element;
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/* Make sure ELEM1 is in the larger class of the two. If not, swap
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them. This way we always scan the shorter list. */
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if (elements[elem1].class_count < elements[elem2].class_count)
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{
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int temp = elem1;
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elem1 = elem2;
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elem2 = temp;
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class_element = elements[elem1].class_element;
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}
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e1 = &(elements[elem1]);
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e2 = &(elements[elem2]);
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/* Keep a count of the number of elements in the list. */
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elements[class_element].class_count
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+= elements[e2->class_element].class_count;
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/* Update the class fields in elem2's class list. */
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e2->class_element = class_element;
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for (p = e2->next; p != e2; p = p->next)
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p->class_element = class_element;
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/* Splice ELEM2's class list into ELEM1's. These are circular
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lists. */
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old_next = e1->next;
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e1->next = e2->next;
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e2->next = old_next;
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return class_element;
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}
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/* Compare elements ELEM1 and ELEM2 from array of integers, given a
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pointer to each. Used to qsort such an array. */
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static int
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elem_compare (elem1, elem2)
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const void *elem1;
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const void *elem2;
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{
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int e1 = * (int *) elem1;
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int e2 = * (int *) elem2;
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if (e1 < e2)
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return -1;
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else if (e1 > e2)
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return 1;
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else
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return 0;
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}
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/* Prints PART to the file pointer FP. The elements of each
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class are sorted. */
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void
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partition_print (part, fp)
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partition part;
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FILE *fp;
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{
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char *done;
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int num_elements = part->num_elements;
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struct partition_elem *elements = part->elements;
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int *class_elements;
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int e;
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/* Flag the elements we've already printed. */
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done = (char *) xmalloc (num_elements);
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memset (done, 0, num_elements);
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/* A buffer used to sort elements in a class. */
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class_elements = (int *) xmalloc (num_elements * sizeof (int));
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fputc ('[', fp);
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for (e = 0; e < num_elements; ++e)
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/* If we haven't printed this element, print its entire class. */
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if (! done[e])
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{
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int c = e;
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int count = elements[elements[e].class_element].class_count;
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int i;
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/* Collect the elements in this class. */
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for (i = 0; i < count; ++i) {
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class_elements[i] = c;
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done[c] = 1;
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c = elements[c].next - elements;
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}
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/* Sort them. */
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qsort ((void *) class_elements, count, sizeof (int), &elem_compare);
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/* Print them. */
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fputc ('(', fp);
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for (i = 0; i < count; ++i)
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fprintf (fp, i == 0 ? "%d" : " %d", class_elements[i]);
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fputc (')', fp);
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}
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fputc (']', fp);
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free (done);
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}
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