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1 | jermar | 1 | /* |
2 | * Copyright (C) 2001-2004 Jakub Jermar |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * |
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9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
29 | #include <mm/heap.h> |
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30 | #include <synch/spinlock.h> |
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31 | #include <func.h> |
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32 | #include <memstr.h> |
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68 | decky | 33 | #include <panic.h> |
1 | jermar | 34 | #include <arch/types.h> |
115 | jermar | 35 | #include <arch/asm.h> |
1 | jermar | 36 | |
37 | /* |
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38 | * First-fit algorithm. |
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39 | * Simple, but hopefully correct. |
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40 | * Chunks being freed are tested for mergability with their neighbours. |
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41 | */ |
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42 | |||
43 | static chunk_t *chunk0; |
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44 | static spinlock_t heaplock; |
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45 | |||
102 | jermar | 46 | void heap_init(__address heap, size_t size) |
1 | jermar | 47 | { |
48 | spinlock_initialize(&heaplock); |
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72 | decky | 49 | memsetb(heap, size, 0); |
1 | jermar | 50 | chunk0 = (chunk_t *) heap; |
51 | chunk0->used = 0; |
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52 | chunk0->size = size - sizeof(chunk_t); |
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53 | chunk0->next = NULL; |
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54 | chunk0->prev = NULL; |
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55 | } |
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56 | |||
57 | /* |
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58 | * Uses first-fit algorithm. |
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59 | */ |
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72 | decky | 60 | void *malloc(size_t size) |
1 | jermar | 61 | { |
62 | pri_t pri; |
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63 | chunk_t *x, *y, *z; |
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64 | |||
65 | if (size == 0) |
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102 | jermar | 66 | panic("zero-size allocation request"); |
1 | jermar | 67 | |
68 | x = chunk0; |
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69 | pri = cpu_priority_high(); |
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70 | spinlock_lock(&heaplock); |
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71 | while (x) { |
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72 | if (x->used || x->size < size) { |
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73 | x = x->next; |
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74 | continue; |
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75 | } |
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76 | |||
77 | x->used = 1; |
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78 | |||
79 | /* |
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80 | * If the chunk exactly matches required size or if truncating |
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81 | * it would not provide enough space for storing a new chunk |
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82 | * header plus at least one byte of data, we are finished. |
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83 | */ |
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84 | if (x->size < size + sizeof(chunk_t) + 1) { |
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85 | spinlock_unlock(&heaplock); |
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86 | cpu_priority_restore(pri); |
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87 | return &x->data[0]; |
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88 | } |
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89 | |||
90 | /* |
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91 | * Truncate x and create a new chunk. |
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92 | */ |
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93 | y = (chunk_t *) (((__address) x) + size + sizeof(chunk_t)); |
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94 | y->used = 0; |
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95 | y->size = x->size - size - sizeof(chunk_t); |
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96 | y->prev = x; |
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97 | y->next = NULL; |
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98 | |||
99 | if (z = x->next) { |
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100 | z->prev = y; |
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101 | y->next = z; |
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102 | } |
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103 | |||
104 | x->size = size; |
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105 | x->next = y; |
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106 | spinlock_unlock(&heaplock); |
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107 | cpu_priority_restore(pri); |
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108 | |||
109 | return &x->data[0]; |
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110 | } |
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111 | spinlock_unlock(&heaplock); |
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112 | cpu_priority_restore(pri); |
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113 | return NULL; |
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114 | } |
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115 | |||
116 | void free(void *ptr) |
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117 | { |
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118 | pri_t pri; |
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119 | chunk_t *x, *y, *z; |
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120 | |||
121 | if (!ptr) |
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122 | panic("free on NULL"); |
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123 | |||
124 | |||
125 | y = (chunk_t *) (((__u8 *) ptr) - sizeof(chunk_t)); |
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126 | if (y->used != 1) |
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127 | panic("freeing unused/damaged chunk"); |
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128 | |||
129 | pri = cpu_priority_high(); |
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130 | spinlock_lock(&heaplock); |
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131 | x = y->prev; |
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132 | z = y->next; |
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133 | /* merge x and y */ |
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134 | if (x && !x->used) { |
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135 | x->size += y->size + sizeof(chunk_t); |
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136 | x->next = z; |
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137 | if (z) |
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138 | z->prev = x; |
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139 | y = x; |
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140 | } |
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141 | /* merge y and z or merge (x merged with y) and z */ |
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142 | if (z && !z->used) { |
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143 | y->size += z->size + sizeof(chunk_t); |
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144 | y->next = z->next; |
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145 | if (z->next) { |
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146 | /* y is either y or x */ |
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147 | z->next->prev = y; |
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148 | } |
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149 | } |
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150 | y->used = 0; |
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151 | spinlock_unlock(&heaplock); |
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152 | cpu_priority_restore(pri); |
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153 | } |