1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright 2002 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #pragma ident "%Z%%M% %I% %E% SMI" 28 29 /* 30 * Yet another list implementation 31 * This is a multipurpose double-linked list. It requires that the first 32 * two structure members of each item are the 'next' and 'prev' pointers. 33 * This works for mblk's and other data types utilized by av1394. 34 * 35 * Locking is provided by the caller. 36 */ 37 38 #include <sys/1394/targets/av1394/av1394_impl.h> 39 40 #define ITEM(i) ((av1394_list_item_t *)(i)) 41 42 /* 43 * av1394_list_init() 44 * Initializes the list 45 */ 46 void av1394_list_init(av1394_list_t * lp)47av1394_list_init(av1394_list_t *lp) 48 { 49 lp->l_head = lp->l_tail = NULL; 50 lp->l_cnt = 0; 51 } 52 53 /* 54 * av1394_list_head() 55 * Returns pointer to the first item in the list (but does not remove it) 56 */ 57 void * av1394_list_head(av1394_list_t * lp)58av1394_list_head(av1394_list_t *lp) 59 { 60 return (lp->l_head); 61 } 62 63 64 /* 65 * av1394_list_put_tail() 66 * Adds item to the end of the list 67 */ 68 void av1394_list_put_tail(av1394_list_t * lp,void * item)69av1394_list_put_tail(av1394_list_t *lp, void *item) 70 { 71 ITEM(item)->i_next = NULL; 72 ITEM(item)->i_prev = lp->l_tail; 73 if (lp->l_tail == NULL) { 74 ASSERT(lp->l_head == 0); 75 ASSERT(lp->l_cnt == 0); 76 lp->l_head = lp->l_tail = item; 77 } else { 78 lp->l_tail->i_next = item; 79 lp->l_tail = item; 80 } 81 lp->l_cnt++; 82 } 83 84 /* 85 * av1394_list_put_head() 86 * Inserts item in the front of the list 87 */ 88 void av1394_list_put_head(av1394_list_t * lp,void * item)89av1394_list_put_head(av1394_list_t *lp, void *item) 90 { 91 ITEM(item)->i_next = lp->l_head; 92 ITEM(item)->i_prev = NULL; 93 if (lp->l_head == NULL) { 94 ASSERT(lp->l_tail == 0); 95 ASSERT(lp->l_cnt == 0); 96 lp->l_head = lp->l_tail = item; 97 } else { 98 lp->l_head->i_prev = item; 99 lp->l_head = item; 100 } 101 lp->l_cnt++; 102 } 103 104 /* 105 * av1394_list_get_head() 106 * Removes and returns an item from the front of the list 107 */ 108 void * av1394_list_get_head(av1394_list_t * lp)109av1394_list_get_head(av1394_list_t *lp) 110 { 111 av1394_list_item_t *item; 112 113 item = lp->l_head; 114 if (item != NULL) { 115 lp->l_head = item->i_next; 116 if (item == lp->l_tail) { 117 ASSERT(lp->l_cnt == 1); 118 ASSERT(lp->l_head == NULL); 119 lp->l_tail = NULL; 120 lp->l_cnt = 0; 121 } else { 122 ASSERT(lp->l_cnt > 1); 123 item->i_next->i_prev = item->i_prev; 124 lp->l_cnt--; 125 } 126 item->i_next = item->i_prev = NULL; 127 } 128 return (item); 129 } 130