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| -rw-r--r-- | libiberty/partition.c | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/libiberty/partition.c b/libiberty/partition.c new file mode 100644 index 0000000..c1d5847 --- /dev/null +++ b/libiberty/partition.c @@ -0,0 +1,185 @@ +/* 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); +} + |