76 lines
1.8 KiB
C
76 lines
1.8 KiB
C
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/*
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* Copyright (c) 1993 by the University of Southern California
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*
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* For copying and distribution information, please see the file
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* <usc-copyr.h>.
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*
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* The menu API and client were written by Kwynn Buess (buess@isi.edu)
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*/
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#include <usc-copyr.h>
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#include <pfs.h>
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#include "menu.h"
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static VLINK swap(VLINK,VLINK);
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/* This prototype of the function performs a bubble sort; this will soon be
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changed. */
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VLINK
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vlink_list_sort(VLINK list)
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{
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VLINK temp;
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int compare_collation_ord(VLINK,VLINK);
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VLINK head = list; /* use the variable 'list' to do final
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rearranging. */
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VLINK next; /* used to do final rearranging. --swa */
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int all_in_order = 0;
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if (!head || !head->next) all_in_order = 1; /* singleton or empty list is
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always in order. */
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while (!all_in_order) {
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all_in_order = 1;
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if (compare_collation_ord(head,head->next) == -1)
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head = swap(head,head->next);
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temp = head;
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all_in_order = 1;
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while (temp->next->next != NULL) {
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if (compare_collation_ord(temp -> next,temp -> next -> next) == -1) {
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all_in_order = 0;
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temp -> next = swap(temp->next,temp->next->next);
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}
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temp = temp -> next;
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}
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}
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/* We now have a singly-linked list of VLINKs rooted at 'head'. */
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/* Now reorder the list of links, so that it meets the standard
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doubly-linked-list conventions. --swa */
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list = NULL;
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for (temp = head ; temp; temp = next) {
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next = temp->next;
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APPEND_ITEM(temp, list);
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}
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return list;
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}
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static VLINK
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swap(VLINK vl1,VLINK vl2) {
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vl1 -> next = vl2 -> next;
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vl2 -> next = vl1;
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vl1 -> previous = vl2;
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vl2 -> previous = vl1 -> previous;
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return vl2;
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}
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