76 lines
1.3 KiB
C
76 lines
1.3 KiB
C
/*
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* Copyright (c) 1987 by Ed James, UC Berkeley. All rights reserved.
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*
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* Copy permission is hereby granted provided that this notice is
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* retained on all partial or complete copies.
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*
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* For more info on this and all of my stuff, mail edjames@berkeley.edu.
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*/
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#include "include.h"
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PLANE *
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newplane()
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{
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return ((PLANE *) calloc(1, sizeof (PLANE)));
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}
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void append(l, p)
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LIST *l;
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PLANE *p;
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{
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PLANE *q = NULL, *r = NULL;
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if (l->head == NULL) {
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p->next = p->prev = NULL;
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l->head = l->tail = p;
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} else {
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q = l -> head;
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while (q != NULL && q->plane_no < p->plane_no) {
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r = q;
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q = q -> next;
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}
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if (q) {
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if (r) {
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p->prev = r;
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r->next = p;
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p->next = q;
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q->prev = p;
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} else {
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p->next = q;
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p->prev = NULL;
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q->prev = p;
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l->head = p;
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}
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} else {
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l->tail->next = p;
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p->next = NULL;
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p->prev = l->tail;
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l->tail = p;
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}
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}
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}
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void delete(l, p)
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LIST *l;
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PLANE *p;
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{
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if (l->head == NULL)
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loser(p, "deleted a non-existant plane! Get help!");
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if (l->head == p && l->tail == p)
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l->head = l->tail = NULL;
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else if (l->head == p) {
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l->head = p->next;
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l->head->prev = NULL;
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} else if (l->tail == p) {
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l->tail = p->prev;
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l->tail->next = NULL;
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} else {
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p->prev->next = p->next;
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p->next->prev = p->prev;
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}
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}
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