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1 /* |
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2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. |
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3 * |
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4 * Copyright 2017 Olaf Wintermann. All rights reserved. |
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5 * |
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6 * Redistribution and use in source and binary forms, with or without |
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7 * modification, are permitted provided that the following conditions are met: |
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8 * |
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9 * 1. 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 * |
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12 * 2. Redistributions in binary form must reproduce the above copyright |
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13 * notice, this list of conditions and the following disclaimer in the |
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14 * documentation and/or other materials provided with the distribution. |
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15 * |
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16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE |
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20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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26 * POSSIBILITY OF SUCH DAMAGE. |
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27 */ |
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28 |
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29 /** |
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30 * @file stack.h |
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31 * |
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32 * Default stack memory allocation implementation. |
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33 * |
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34 * @author Mike Becker |
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35 * @author Olaf Wintermann |
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36 */ |
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37 |
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38 #ifndef UCX_STACK_H |
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39 #define UCX_STACK_H |
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40 |
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41 #include <ucx/ucx.h> |
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42 #include <ucx/allocator.h> |
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43 |
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44 #ifdef __cplusplus |
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45 extern "C" { |
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46 #endif |
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47 |
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48 |
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49 /** |
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50 * UCX stack structure. |
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51 */ |
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52 typedef struct { |
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53 /** UcxAllocator based on this stack */ |
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54 UcxAllocator allocator; |
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55 |
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56 /** Stack size. */ |
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57 size_t size; |
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58 |
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59 /** Pointer to the bottom of the stack */ |
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60 char *space; |
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61 |
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62 /** Pointer to the top of the stack */ |
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63 char *top; |
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64 } UcxStack; |
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65 |
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66 /** |
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67 * Metadata for each UCX stack element. |
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68 */ |
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69 struct ucx_stack_metadata { |
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70 /** |
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71 * Location of the previous element (<code>NULL</code> if this is the first) |
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72 */ |
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73 char *prev; |
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74 |
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75 /** Size of this element */ |
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76 size_t size; |
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77 }; |
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78 |
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79 /** |
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80 * Initializes UcxStack structure with memory. |
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81 * |
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82 * @param stack a pointer to an uninitialized stack structure |
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83 * @param space the memory area that shall be managed |
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84 * @param size size of the memory area |
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85 * @return a new UcxStack structure |
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86 */ |
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87 void ucx_stack_init(UcxStack *stack, char* space, size_t size); |
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88 |
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89 /** |
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90 * Allocates stack memory. |
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91 * |
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92 * @param stack a pointer to the stack |
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93 * @param n amount of memory to allocate |
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94 * @return a pointer to the allocated memory |
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95 * @see ucx_allocator_malloc() |
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96 */ |
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97 void *ucx_stack_malloc(UcxStack *stack, size_t n); |
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98 |
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99 /** |
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100 * Alias for #ucx_stack_malloc(). |
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101 * @param stack a pointer to the stack |
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102 * @param n amount of memory to allocate |
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103 * @return a pointer to the allocated memory |
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104 * @see ucx_stack_malloc |
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105 */ |
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106 #define ucx_stack_push(stack, n) ucx_stack_malloc(stack, n) |
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107 |
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108 /** |
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109 * Allocates an array of stack memory |
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110 * |
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111 * The content of the allocated memory is set to zero. |
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112 * |
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113 * @param stack a pointer to the stack |
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114 * @param nelem amount of elements to allocate |
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115 * @param elsize amount of memory per element |
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116 * @return a pointer to the allocated memory |
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117 * @see ucx_allocator_calloc() |
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118 */ |
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119 void *ucx_stack_calloc(UcxStack *stack, size_t nelem, size_t elsize); |
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120 |
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121 /** |
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122 * Alias for #ucx_stack_calloc(). |
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123 * |
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124 * @param stack a pointer to the stack |
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125 * @param n amount of elements to allocate |
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126 * @param elsize amount of memory per element |
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127 * @return a pointer to the allocated memory |
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128 * @see ucx_stack_calloc |
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129 */ |
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130 #define ucx_stack_pusharr(stack,n,elsize) ucx_stack_calloc(stack,n,elssize) |
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131 |
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132 /** |
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133 * Reallocates memory on the stack. |
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134 * |
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135 * Shrinking memory is always safe. Extending memory can be very expensive. |
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136 * |
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137 * @param stack the stack |
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138 * @param ptr a pointer to the memory that shall be reallocated |
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139 * @param n the new size of the memory |
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140 * @return a pointer to the new location of the memory |
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141 * @see ucx_allocator_realloc() |
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142 */ |
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143 void *ucx_stack_realloc(UcxStack *stack, void *ptr, size_t n); |
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144 |
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145 /** |
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146 * Frees memory on the stack. |
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147 * |
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148 * Freeing stack memory behaves in a special way. |
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149 * |
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150 * If the element, that should be freed, is the top most element of the stack, |
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151 * it is removed from the stack. Otherwise it is marked as freed. Marked |
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152 * elements are removed, when they become the top most elements of the stack. |
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153 * |
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154 * @param stack a pointer to the stack |
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155 * @param ptr a pointer to the memory that shall be freed |
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156 */ |
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157 void ucx_stack_free(UcxStack *stack, void *ptr); |
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158 |
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159 |
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160 /** |
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161 * Returns the size of the top most element. |
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162 * @param stack a pointer to the stack |
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163 * @return the size of the top most element |
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164 */ |
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165 #define ucx_stack_topsize(stack) ((stack)->top ? ((struct ucx_stack_metadata*)\ |
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166 (stack)->top - 1)->size : 0) |
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167 |
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168 /** |
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169 * Removes the top most element from the stack and copies the content to <code> |
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170 * dest</code>, if specified. |
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171 * |
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172 * Use #ucx_stack_topsize()# to get the amount of memory that must be available |
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173 * at the location of <code>dest</code>. |
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174 * |
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175 * @param stack a pointer to the stack |
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176 * @param dest the location where the contents shall be written to, or <code> |
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177 * NULL</code>, if the element shall only be removed. |
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178 * @see ucx_stack_free |
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179 * @see ucx_stack_popn |
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180 */ |
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181 #define ucx_stack_pop(stack, dest) ucx_stack_popn(stack, dest, (size_t)-1) |
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182 |
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183 /** |
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184 * Removes the top most element from the stack and copies the content to <code> |
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185 * dest</code>. |
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186 * |
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187 * In contrast to #ucx_stack_pop() the <code>dest</code> pointer <code>MUST |
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188 * NOT</code> be <code>NULL</code>. |
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189 * |
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190 * @param stack a pointer to the stack |
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191 * @param dest the location where the contents shall be written to |
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192 * @param n copies at most n elements to <code>dest</code> |
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193 * @see ucx_stack_pop |
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194 */ |
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195 void ucx_stack_popn(UcxStack *stack, void *dest, size_t n); |
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196 |
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197 /** |
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198 * Returns the remaining available memory on the specified stack. |
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199 * |
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200 * @param stack a pointer to the stack |
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201 * @return the remaining available memory |
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202 */ |
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203 size_t ucx_stack_avail(UcxStack *stack); |
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204 |
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205 /** |
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206 * Checks, if the stack is empty. |
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207 * |
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208 * @param stack a pointer to the stack |
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209 * @return nonzero, if the stack is empty, zero otherwise |
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210 */ |
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211 #define ucx_stack_empty(stack) (!(stack)->top) |
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212 |
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213 /** |
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214 * Computes a recommended size for the stack memory area. Note, that |
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215 * reallocations have not been taken into account, so you might need to reserve |
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216 * twice as much memory to allow many reallocations. |
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217 * |
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218 * @param size the approximate payload |
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219 * @param elems the approximate count of element allocations |
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220 * @return a recommended size for the stack space based on the information |
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221 * provided |
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222 */ |
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223 #define ucx_stack_dim(size, elems) (size+sizeof(struct ucx_stack_metadata) * \ |
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224 (elems + 1)) |
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225 |
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226 |
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227 #ifdef __cplusplus |
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228 } |
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229 #endif |
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230 |
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231 #endif /* UCX_STACK_H */ |
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232 |