1 | /*
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2 | tre-mem.c - TRE memory allocator
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3 |
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4 | Copyright (c) 2001-2009 Ville Laurikari <vl@iki.fi>
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5 | All rights reserved.
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6 |
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7 | Redistribution and use in source and binary forms, with or without
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8 | modification, are permitted provided that the following conditions
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9 | are met:
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10 |
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11 | 1. Redistributions of source code must retain the above copyright
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12 | notice, this list of conditions and the following disclaimer.
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13 |
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14 | 2. Redistributions in binary form must reproduce the above copyright
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15 | notice, this list of conditions and the following disclaimer in the
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16 | documentation and/or other materials provided with the distribution.
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17 |
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18 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS
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19 | ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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20 | LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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21 | A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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22 | HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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23 | SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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24 | LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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25 | DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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26 | THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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27 | (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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28 | OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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29 |
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30 | */
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31 |
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32 | /*
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33 | This memory allocator is for allocating small memory blocks efficiently
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34 | in terms of memory overhead and execution speed. The allocated blocks
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35 | cannot be freed individually, only all at once. There can be multiple
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36 | allocators, though.
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37 | */
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38 |
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39 | #include <stdlib.h>
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40 | #include <string.h>
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41 |
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42 | #include "tre.h"
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43 |
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44 | /*
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45 | This memory allocator is for allocating small memory blocks efficiently
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46 | in terms of memory overhead and execution speed. The allocated blocks
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47 | cannot be freed individually, only all at once. There can be multiple
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48 | allocators, though.
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49 | */
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50 |
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51 | /* Returns a new memory allocator or NULL if out of memory. */
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52 | tre_mem_t
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53 | tre_mem_new_impl(int provided, void *provided_block)
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54 | {
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55 | tre_mem_t mem;
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56 | if (provided)
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57 | {
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58 | mem = provided_block;
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59 | memset(mem, 0, sizeof(*mem));
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60 | }
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61 | else
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62 | mem = xcalloc(1, sizeof(*mem));
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63 | if (mem == NULL)
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64 | return NULL;
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65 | return mem;
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66 | }
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67 |
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68 |
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69 | /* Frees the memory allocator and all memory allocated with it. */
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70 | void
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71 | tre_mem_destroy(tre_mem_t mem)
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72 | {
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73 | tre_list_t *tmp, *l = mem->blocks;
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74 |
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75 | while (l != NULL)
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76 | {
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77 | xfree(l->data);
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78 | tmp = l->next;
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79 | xfree(l);
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80 | l = tmp;
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81 | }
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82 | xfree(mem);
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83 | }
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84 |
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85 |
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86 | /* Allocates a block of `size' bytes from `mem'. Returns a pointer to the
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87 | allocated block or NULL if an underlying malloc() failed. */
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88 | void *
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89 | tre_mem_alloc_impl(tre_mem_t mem, int provided, void *provided_block,
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90 | int zero, size_t size)
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91 | {
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92 | void *ptr;
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93 |
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94 | if (mem->failed)
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95 | {
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96 | return NULL;
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97 | }
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98 |
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99 | if (mem->n < size)
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100 | {
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101 | /* We need more memory than is available in the current block.
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102 | Allocate a new block. */
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103 | tre_list_t *l;
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104 | if (provided)
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105 | {
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106 | if (provided_block == NULL)
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107 | {
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108 | mem->failed = 1;
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109 | return NULL;
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110 | }
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111 | mem->ptr = provided_block;
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112 | mem->n = TRE_MEM_BLOCK_SIZE;
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113 | }
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114 | else
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115 | {
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116 | int block_size;
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117 | if (size * 8 > TRE_MEM_BLOCK_SIZE)
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118 | block_size = size * 8;
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119 | else
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120 | block_size = TRE_MEM_BLOCK_SIZE;
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121 | l = xmalloc(sizeof(*l));
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122 | if (l == NULL)
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123 | {
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124 | mem->failed = 1;
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125 | return NULL;
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126 | }
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127 | l->data = xmalloc(block_size);
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128 | if (l->data == NULL)
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129 | {
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130 | xfree(l);
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131 | mem->failed = 1;
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132 | return NULL;
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133 | }
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134 | l->next = NULL;
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135 | if (mem->current != NULL)
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136 | mem->current->next = l;
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137 | if (mem->blocks == NULL)
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138 | mem->blocks = l;
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139 | mem->current = l;
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140 | mem->ptr = l->data;
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141 | mem->n = block_size;
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142 | }
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143 | }
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144 |
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145 | /* Make sure the next pointer will be aligned. */
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146 | size += ALIGN(mem->ptr + size, long);
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147 |
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148 | /* Allocate from current block. */
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149 | ptr = mem->ptr;
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150 | mem->ptr += size;
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151 | mem->n -= size;
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152 |
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153 | /* Set to zero if needed. */
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154 | if (zero)
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155 | memset(ptr, 0, size);
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156 |
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157 | return ptr;
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158 | }
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