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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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228 | giacomo | 103 | __b_fastmutex_unlock(&q->mutex); |
2 | pj | 104 | return ret; |
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 | } |