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| 2 | pj | 1 | /* |
| 2 | * Project: S.Ha.R.K. |
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| 3 | * |
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| 4 | * Coordinators: |
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| 5 | * Giorgio Buttazzo <giorgio@sssup.it> |
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| 6 | * Paolo Gai <pj@gandalf.sssup.it> |
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| 7 | * |
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| 8 | * Authors : |
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| 9 | * Paolo Gai <pj@gandalf.sssup.it> |
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| 10 | * Massimiliano Giorgi <massy@gandalf.sssup.it> |
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| 11 | * Luca Abeni <luca@gandalf.sssup.it> |
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| 12 | * (see the web pages for full authors list) |
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| 13 | * |
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| 14 | * ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy) |
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| 15 | * |
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| 16 | * http://www.sssup.it |
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| 17 | * http://retis.sssup.it |
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| 18 | * http://shark.sssup.it |
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| 19 | */ |
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| 20 | |||
| 21 | /* |
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| 22 | * Copyright (C) 2000 Massimiliano Giorgi |
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| 23 | * |
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| 24 | * This program is free software; you can redistribute it and/or modify |
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| 25 | * it under the terms of the GNU General Public License as published by |
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| 26 | * the Free Software Foundation; either version 2 of the License, or |
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| 27 | * (at your option) any later version. |
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| 28 | * |
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| 29 | * This program is distributed in the hope that it will be useful, |
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| 30 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 31 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 32 | * GNU General Public License for more details. |
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| 33 | * |
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| 34 | * You should have received a copy of the GNU General Public License |
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| 35 | * along with this program; if not, write to the Free Software |
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| 36 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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| 37 | * |
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| 38 | */ |
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| 39 | |||
| 40 | #include "bqueue.h" |
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| 41 | #include "glue.h" |
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| 42 | |||
| 43 | int sstf_init(sstf_queue_t *q) |
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| 44 | { |
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| 45 | __b_fastmutex_init(&q->mutex); |
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| 46 | q->disk=NULL; |
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| 47 | q->lqueue=NULL; |
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| 48 | q->hqueue=NULL; |
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| 49 | q->actual=NULL; |
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| 50 | q->counter=0; |
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| 51 | return 0; |
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| 52 | } |
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| 53 | |||
| 54 | int sstf_numelements(sstf_queue_t *q) |
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| 55 | { |
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| 56 | return q->counter; |
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| 57 | } |
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| 58 | |||
| 59 | int sstf_insertrequest(sstf_queue_t *q, request_prologue_t *e) |
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| 60 | { |
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| 61 | request_prologue_t *p,*o; |
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| 62 | |||
| 63 | __b_fastmutex_lock(&q->mutex); |
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| 64 | if (q->actual==NULL) |
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| 65 | q->actual=e; |
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| 66 | else { |
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| 67 | if (e->cylinder<=q->actual->cylinder) { |
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| 68 | /* insert into low queue */ |
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| 69 | o=NULL; |
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| 70 | p=q->lqueue; |
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| 71 | while (p!=NULL) { |
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| 72 | if (e->cylinder>p->cylinder) break; |
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| 73 | o=p; |
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| 74 | p=p->x.next; |
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| 75 | } |
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| 76 | if (o==NULL) q->lqueue=e; |
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| 77 | else o->x.next=e; |
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| 78 | e->x.next=p; |
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| 79 | } else { |
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| 80 | /* insert into high queue */ |
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| 81 | o=NULL; |
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| 82 | p=q->hqueue; |
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| 83 | while (p!=NULL) { |
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| 84 | if (e->cylinder<p->cylinder) break; |
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| 85 | o=p; |
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| 86 | p=p->x.next; |
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| 87 | } |
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| 88 | if (o==NULL) q->hqueue=e; |
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| 89 | else o->x.next=e; |
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| 90 | e->x.next=p; |
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| 91 | } |
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| 92 | } |
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| 93 | q->counter++; |
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| 94 | __b_fastmutex_unlock(&q->mutex); |
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| 95 | return 0; |
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| 96 | } |
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| 97 | |||
| 98 | request_prologue_t *sstf_getrequest(sstf_queue_t *q) |
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| 99 | { |
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| 100 | request_prologue_t *ret; |
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| 101 | __b_fastmutex_lock(&q->mutex); |
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| 102 | ret=q->actual; |
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| 103 | __b_fastmutex_lock(&q->mutex); |
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| 104 | return ret; |
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| 105 | } |
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| 106 | |||
| 107 | int sstf_removerequest(sstf_queue_t *q) |
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| 108 | { |
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| 109 | __b_fastmutex_lock(&q->mutex); |
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| 110 | assertk(q->actual!=NULL); |
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| 111 | if (q->lqueue==NULL) { |
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| 112 | if (q->hqueue==NULL) { |
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| 113 | |||
| 114 | /* lqueue==NULL && hqueue==NULL */ |
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| 115 | |||
| 116 | q->actual=NULL; |
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| 117 | |||
| 118 | } else { |
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| 119 | |||
| 120 | /* lqueue==NULL && hqueue!=NULL */ |
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| 121 | |||
| 122 | q->actual=q->hqueue; |
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| 123 | q->hqueue=q->hqueue->x.next; |
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| 124 | |||
| 125 | } |
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| 126 | } else { |
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| 127 | if (q->hqueue==NULL) { |
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| 128 | |||
| 129 | /* lqueue!=NULL && hqueue==NULL */ |
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| 130 | |||
| 131 | q->actual=q->lqueue; |
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| 132 | q->lqueue=q->lqueue->x.next; |
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| 133 | |||
| 134 | } else { |
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| 135 | |||
| 136 | /* lqueue!=NULL && hqueue!=NULL */ |
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| 137 | |||
| 138 | int dl,dh; |
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| 139 | dh=q->hqueue->cylinder-q->actual->cylinder; |
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| 140 | dl=q->actual->cylinder-q->lqueue->cylinder; |
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| 141 | if (dh<dl) { |
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| 142 | q->actual=q->hqueue; |
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| 143 | q->hqueue=q->hqueue->x.next; |
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| 144 | } else { |
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| 145 | q->actual=q->lqueue; |
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| 146 | q->lqueue=q->lqueue->x.next; |
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| 147 | } |
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| 148 | |||
| 149 | } |
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| 150 | } |
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| 151 | |||
| 152 | q->counter--; |
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| 153 | __b_fastmutex_unlock(&q->mutex); |
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| 154 | return 0; |
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| 155 | } |