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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 | |||
22 | /* |
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23 | * Copyright (C) 2000 Massimiliano Giorgi |
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24 | * |
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25 | * This program is free software; you can redistribute it and/or modify |
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26 | * it under the terms of the GNU General Public License as published by |
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27 | * the Free Software Foundation; either version 2 of the License, or |
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28 | * (at your option) any later version. |
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29 | * |
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30 | * This program is distributed in the hope that it will be useful, |
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31 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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32 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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33 | * GNU General Public License for more details. |
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34 | * |
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35 | * You should have received a copy of the GNU General Public License |
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36 | * along with this program; if not, write to the Free Software |
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37 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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38 | * |
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39 | */ |
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40 | |||
41 | #include "bqueue.h" |
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42 | #include "glue.h" |
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43 | |||
44 | int clook_init(clook_queue_t *q) |
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45 | { |
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46 | __b_fastmutex_init(&q->mutex); |
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47 | q->disk=NULL; |
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48 | q->queue[0]=NULL; |
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49 | q->queue[1]=NULL; |
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50 | q->act=0; |
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51 | q->counter=0; |
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52 | return 0; |
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53 | } |
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54 | |||
55 | int clook_numelements(clook_queue_t *q) |
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56 | { |
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57 | return q->counter; |
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58 | } |
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59 | |||
60 | /* 0 -> no starvation */ |
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61 | /* 1 -> possible starvation */ |
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62 | #define STARVATION 0 |
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63 | |||
64 | int clook_insertrequest(clook_queue_t *q, request_prologue_t *e) |
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65 | { |
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66 | request_prologue_t *p,*o; |
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67 | |||
68 | __b_fastmutex_lock(&q->mutex); |
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69 | |||
70 | if (q->queue[q->act]==NULL) { |
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71 | q->queue[q->act]=e; |
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72 | e->x.next=NULL; |
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73 | } else if (e->cylinder>q->queue[q->act]->cylinder-STARVATION) { |
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74 | o=q->queue[q->act]; |
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75 | p=o->x.next; |
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76 | while (p!=NULL) { |
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77 | if (e->cylinder<p->cylinder) break; |
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78 | o=p; |
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79 | p=p->x.next; |
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80 | } |
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81 | o->x.next=e; |
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82 | e->x.next=p; |
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83 | } else { |
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84 | o=NULL; |
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85 | p=q->queue[q->act^1]; |
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86 | while (p!=NULL) { |
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87 | if (e->cylinder<p->cylinder) break; |
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88 | o=p; |
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89 | p=p->x.next; |
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90 | } |
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91 | if (o==NULL) q->queue[q->act^1]=e; |
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92 | else o->x.next=e; |
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93 | e->x.next=p; |
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94 | } |
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95 | |||
96 | q->counter++; |
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97 | __b_fastmutex_unlock(&q->mutex); |
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98 | return 0; |
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99 | } |
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100 | |||
101 | request_prologue_t *clook_getrequest(clook_queue_t *q) |
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102 | { |
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103 | request_prologue_t *ret; |
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104 | __b_fastmutex_lock(&q->mutex); |
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105 | ret=q->queue[q->act]; |
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106 | if (ret==NULL) { |
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107 | q->act^=1; |
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108 | ret=q->queue[q->act]; |
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109 | } |
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110 | __b_fastmutex_lock(&q->mutex); |
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111 | return ret; |
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112 | } |
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113 | |||
114 | int clook_removerequest(clook_queue_t *q) |
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115 | { |
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116 | __b_fastmutex_lock(&q->mutex); |
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117 | assertk(q->queue[q->act]!=NULL); |
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118 | q->queue[q->act]=q->queue[q->act]->x.next; |
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119 | q->counter--; |
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120 | __b_fastmutex_unlock(&q->mutex); |
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121 | return 0; |
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122 | } |