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1 /* Support for dynamic arrays.
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428
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2 Copyright (C) 1993 Sun Microsystems, Inc.
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3 Copyright (C) 2002, 2003 Ben Wing.
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428
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4
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5 This file is part of XEmacs.
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6
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7 XEmacs is free software; you can redistribute it and/or modify it
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8 under the terms of the GNU General Public License as published by the
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9 Free Software Foundation; either version 2, or (at your option) any
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10 later version.
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11
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12 XEmacs is distributed in the hope that it will be useful, but WITHOUT
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13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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15 for more details.
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16
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17 You should have received a copy of the GNU General Public License
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18 along with XEmacs; see the file COPYING. If not, write to
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19 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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20 Boston, MA 02111-1307, USA. */
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21
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22 /* Synched up with: Not in FSF. */
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23
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24 /* Written by Ben Wing, December 1993. */
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25
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26 /*
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27
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28 A "dynamic array" is a contiguous array of fixed-size elements where there
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29 is no upper limit (except available memory) on the number of elements in the
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30 array. Because the elements are maintained contiguously, space is used
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31 efficiently (no per-element pointers necessary) and random access to a
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32 particular element is in constant time. At any one point, the block of memory
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33 that holds the array has an upper limit; if this limit is exceeded, the
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34 memory is realloc()ed into a new array that is twice as big. Assuming that
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35 the time to grow the array is on the order of the new size of the array
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36 block, this scheme has a provably constant amortized time (i.e. average
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37 time over all additions).
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38
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39 When you add elements or retrieve elements, pointers are used. Note that
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40 the element itself (of whatever size it is), and not the pointer to it,
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41 is stored in the array; thus you do not have to allocate any heap memory
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42 on your own. Also, returned pointers are only guaranteed to be valid
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43 until the next operation that changes the length of the array.
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44
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45 This is a container object. Declare a dynamic array of a specific type
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46 as follows:
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47
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48 typedef struct
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49 {
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50 Dynarr_declare (mytype);
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51 } mytype_dynarr;
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52
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53 Use the following functions/macros:
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54
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55 void *Dynarr_new(type)
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56 [MACRO] Create a new dynamic-array object, with each element of the
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57 specified type. The return value is cast to (type##_dynarr).
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58 This requires following the convention that types are declared in
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59 such a way that this type concatenation works. In particular, TYPE
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60 must be a symbol, not an arbitrary C type.
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61
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62 Dynarr_add(d, el)
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63 [MACRO] Add an element to the end of a dynamic array. EL is a pointer
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64 to the element; the element itself is stored in the array, however.
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65 No function call is performed unless the array needs to be resized.
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66
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67 Dynarr_add_many(d, base, len)
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68 [MACRO] Add LEN elements to the end of the dynamic array. The elements
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69 should be contiguous in memory, starting at BASE. If BASE if NULL,
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70 just make space for the elements; don't actually add them.
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71
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72 Dynarr_insert_many_at_start(d, base, len)
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73 [MACRO] Append LEN elements to the beginning of the dynamic array.
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74 The elements should be contiguous in memory, starting at BASE.
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75 If BASE if NULL, just make space for the elements; don't actually
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76 add them.
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77
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78 Dynarr_insert_many(d, base, len, start)
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79 Insert LEN elements to the dynamic array starting at position
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80 START. The elements should be contiguous in memory, starting at BASE.
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81 If BASE if NULL, just make space for the elements; don't actually
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82 add them.
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83
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84 Dynarr_delete(d, i)
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85 [MACRO] Delete an element from the dynamic array at position I.
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86
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87 Dynarr_delete_many(d, start, len)
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88 Delete LEN elements from the dynamic array starting at position
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89 START.
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90
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91 Dynarr_delete_by_pointer(d, p)
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92 [MACRO] Delete an element from the dynamic array at pointer P,
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93 which must point within the block of memory that stores the data.
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94 P should be obtained using Dynarr_atp().
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95
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96 int Dynarr_length(d)
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97 [MACRO] Return the number of elements currently in a dynamic array.
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98
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99 int Dynarr_largest(d)
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100 [MACRO] Return the maximum value that Dynarr_length(d) would
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101 ever have returned.
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102
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103 type Dynarr_at(d, i)
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104 [MACRO] Return the element at the specified index (no bounds checking
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105 done on the index). The element itself is returned, not a pointer
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106 to it.
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107
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108 type *Dynarr_atp(d, i)
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109 [MACRO] Return a pointer to the element at the specified index (no
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110 bounds checking done on the index). The pointer may not be valid
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111 after an element is added to or removed from the array.
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112
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113 Dynarr_reset(d)
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114 [MACRO] Reset the length of a dynamic array to 0.
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115
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116 Dynarr_free(d)
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117 Destroy a dynamic array and the memory allocated to it.
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118
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119 Use the following global variable:
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120
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121 Dynarr_min_size
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122 Minimum allowable size for a dynamic array when it is resized.
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123
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124 */
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125
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126 #include <config.h>
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127 #include "lisp.h"
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128
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129 static int Dynarr_min_size = 8;
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130
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131 static void
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132 Dynarr_realloc (Dynarr *dy, int new_size)
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133 {
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134 if (DUMPEDP (dy->base))
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135 {
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136 void *new_base = malloc (new_size);
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137 memcpy (new_base, dy->base, dy->max > new_size ? dy->max : new_size);
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138 dy->base = new_base;
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139 }
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140 else
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141 dy->base = xrealloc (dy->base, new_size);
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142 }
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143
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144 void *
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145 Dynarr_newf (int elsize)
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146 {
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147 Dynarr *d = xnew_and_zero (Dynarr);
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148 d->elsize = elsize;
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149
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150 return d;
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151 }
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152
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153 void
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154 Dynarr_resize (void *d, int size)
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155 {
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156 int newsize;
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157 double multiplier;
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158 Dynarr *dy = (Dynarr *) Dynarr_verify (d);
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159
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160 if (dy->max <= 8)
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161 multiplier = 2;
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162 else
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163 multiplier = 1.5;
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164
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165 for (newsize = dy->max; newsize < size;)
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166 newsize = max (Dynarr_min_size, (int) (multiplier * newsize));
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167
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168 /* Don't do anything if the array is already big enough. */
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169 if (newsize > dy->max)
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170 {
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171 Dynarr_realloc (dy, newsize*dy->elsize);
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172 dy->max = newsize;
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173 }
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174 }
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175
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176 /* Add a number of contiguous elements to the array starting at START. */
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177 void
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178 Dynarr_insert_many (void *d, const void *el, int len, int start)
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179 {
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180 Dynarr *dy = (Dynarr *) Dynarr_verify (d);
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181
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182 Dynarr_resize (dy, dy->cur+len);
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183 #if 0
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184 /* WTF? We should be catching these problems. */
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185 /* Silently adjust start to be valid. */
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186 if (start > dy->cur)
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187 start = dy->cur;
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188 else if (start < 0)
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189 start = 0;
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190 #else
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191 assert (start >= 0 && start <= dy->cur);
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192 #endif
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193
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194 if (start != dy->cur)
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195 {
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196 memmove ((char *) dy->base + (start + len)*dy->elsize,
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197 (char *) dy->base + start*dy->elsize,
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198 (dy->cur - start)*dy->elsize);
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199 }
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200 if (el)
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201 memcpy ((char *) dy->base + start*dy->elsize, el, len*dy->elsize);
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202 dy->cur += len;
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203
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204 if (dy->cur > dy->largest)
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205 dy->largest = dy->cur;
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206 }
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207
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208 void
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209 Dynarr_delete_many (void *d, int start, int len)
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210 {
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211 Dynarr *dy = (Dynarr *) Dynarr_verify (d);
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212
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213 assert (start >= 0 && len >= 0 && start + len <= dy->cur);
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214 memmove ((char *) dy->base + start*dy->elsize,
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215 (char *) dy->base + (start + len)*dy->elsize,
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216 (dy->cur - start - len)*dy->elsize);
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217 dy->cur -= len;
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218 }
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219
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220 void
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221 Dynarr_free (void *d)
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222 {
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223 Dynarr *dy = (Dynarr *) d;
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224
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225 if (dy->base && !DUMPEDP (dy->base))
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226 xfree (dy->base);
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227 if(!DUMPEDP (dy))
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228 xfree (dy);
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229 }
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230
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231 #ifdef MEMORY_USAGE_STATS
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232
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233 /* Return memory usage for Dynarr D. The returned value is the total
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234 amount of bytes actually being used for the Dynarr, including all
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235 overhead. The extra amount of space in the Dynarr that is
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236 allocated beyond what was requested is returned in DYNARR_OVERHEAD
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237 in STATS. The extra amount of space that malloc() allocates beyond
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238 what was requested of it is returned in MALLOC_OVERHEAD in STATS.
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239 See the comment above the definition of this structure. */
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240
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241 Bytecount
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242 Dynarr_memory_usage (void *d, struct overhead_stats *stats)
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243 {
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244 Bytecount total = 0;
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245 Dynarr *dy = (Dynarr *) d;
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246
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247 /* We have to be a bit tricky here because not all of the
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248 memory that malloc() will claim as "requested" was actually
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249 requested. */
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250
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251 if (dy->base)
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252 {
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253 Bytecount malloc_used = malloced_storage_size (dy->base,
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254 dy->elsize * dy->max, 0);
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255 /* #### This may or may not be correct. Some Dynarrs would
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256 prefer that we use dy->cur instead of dy->largest here. */
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257 Bytecount was_requested = dy->elsize * dy->largest;
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258 Bytecount dynarr_overhead = dy->elsize * (dy->max - dy->largest);
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259
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260 total += malloc_used;
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261 stats->was_requested += was_requested;
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262 stats->dynarr_overhead += dynarr_overhead;
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263 /* And the remainder must be malloc overhead. */
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264 stats->malloc_overhead +=
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265 malloc_used - was_requested - dynarr_overhead;
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266 }
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267
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268 total += malloced_storage_size (d, sizeof (*dy), stats);
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269
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270 return total;
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271 }
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272
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273 #endif /* MEMORY_USAGE_STATS */
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