1 | /* |
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2 | * tclAlloc.c -- |
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3 | * |
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4 | * This is a very fast storage allocator. It allocates blocks of a |
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5 | * small number of different sizes, and keeps free lists of each size. |
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6 | * Blocks that don't exactly fit are passed up to the next larger size. |
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7 | * Blocks over a certain size are directly allocated from the system. |
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8 | * |
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9 | * Copyright (c) 1983 Regents of the University of California. |
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10 | * Copyright (c) 1996-1997 Sun Microsystems, Inc. |
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11 | * |
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12 | * Portions contributed by Chris Kingsley, Jack Jansen and Ray Johnson. |
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13 | * |
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14 | * See the file "license.terms" for information on usage and redistribution |
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15 | * of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
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16 | * |
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17 | * RCS: @(#) $Id: tclAlloc.c,v 1.1 2008-06-04 13:58:03 demin Exp $ |
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18 | */ |
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19 | |
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20 | #include "tclInt.h" |
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21 | #include "tclPort.h" |
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22 | |
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23 | #ifdef TCL_DEBUG |
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24 | # define DEBUG |
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25 | /* #define MSTATS */ |
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26 | # define RCHECK |
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27 | #endif |
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28 | |
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29 | //typedef unsigned long caddr_t; |
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30 | |
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31 | /* |
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32 | * The overhead on a block is at least 4 bytes. When free, this space |
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33 | * contains a pointer to the next free block, and the bottom two bits must |
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34 | * be zero. When in use, the first byte is set to MAGIC, and the second |
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35 | * byte is the size index. The remaining bytes are for alignment. |
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36 | * If range checking is enabled then a second word holds the size of the |
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37 | * requested block, less 1, rounded up to a multiple of sizeof(RMAGIC). |
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38 | * The order of elements is critical: ov_magic must overlay the low order |
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39 | * bits of ov_next, and ov_magic can not be a valid ov_next bit pattern. |
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40 | */ |
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41 | |
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42 | union overhead { |
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43 | union overhead *ov_next; /* when free */ |
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44 | struct { |
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45 | unsigned char ovu_magic0; /* magic number */ |
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46 | unsigned char ovu_index; /* bucket # */ |
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47 | unsigned char ovu_unused; /* unused */ |
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48 | unsigned char ovu_magic1; /* other magic number */ |
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49 | #ifdef RCHECK |
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50 | unsigned short ovu_rmagic; /* range magic number */ |
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51 | unsigned long ovu_size; /* actual block size */ |
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52 | #endif |
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53 | } ovu; |
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54 | #define ov_magic0 ovu.ovu_magic0 |
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55 | #define ov_magic1 ovu.ovu_magic1 |
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56 | #define ov_index ovu.ovu_index |
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57 | #define ov_rmagic ovu.ovu_rmagic |
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58 | #define ov_size ovu.ovu_size |
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59 | }; |
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60 | |
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61 | |
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62 | #define MAGIC 0xef /* magic # on accounting info */ |
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63 | #define RMAGIC 0x5555 /* magic # on range info */ |
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64 | |
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65 | #ifdef RCHECK |
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66 | #define RSLOP sizeof (unsigned short) |
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67 | #else |
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68 | #define RSLOP 0 |
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69 | #endif |
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70 | |
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71 | #define OVERHEAD (sizeof(union overhead) + RSLOP) |
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72 | |
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73 | /* |
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74 | * nextf[i] is the pointer to the next free block of size 2^(i+3). The |
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75 | * smallest allocatable block is 8 bytes. The overhead information |
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76 | * precedes the data area returned to the user. |
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77 | */ |
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78 | |
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79 | #define NBUCKETS 13 |
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80 | #define MAXMALLOC (1<<(NBUCKETS+2)) |
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81 | |
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82 | #ifdef MSTATS |
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83 | |
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84 | /* |
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85 | * nmalloc[i] is the difference between the number of mallocs and frees |
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86 | * for a given block size. |
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87 | */ |
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88 | |
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89 | static unsigned int nmalloc[NBUCKETS+1]; |
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90 | #include <stdio.h> |
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91 | #endif |
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92 | |
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93 | #if defined(DEBUG) || defined(RCHECK) |
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94 | #define ASSERT(p) if (!(p)) panic(# p) |
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95 | #define RANGE_ASSERT(p) if (!(p)) panic(# p) |
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96 | #else |
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97 | #define ASSERT(p) |
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98 | #define RANGE_ASSERT(p) |
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99 | #endif |
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100 | |
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101 | /* |
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102 | *---------------------------------------------------------------------- |
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103 | * |
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104 | * TclpAlloc -- |
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105 | * |
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106 | * Allocate more memory. |
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107 | * |
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108 | * Results: |
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109 | * None. |
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110 | * |
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111 | * Side effects: |
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112 | * None. |
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113 | * |
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114 | *---------------------------------------------------------------------- |
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115 | */ |
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116 | |
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117 | char * |
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118 | TclpAlloc( |
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119 | unsigned int nbytes) /* Number of bytes to allocate. */ |
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120 | { |
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121 | return (char*) malloc(nbytes); |
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122 | } |
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123 | |
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124 | /* |
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125 | *---------------------------------------------------------------------- |
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126 | * |
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127 | * TclpFree -- |
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128 | * |
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129 | * Free memory. |
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130 | * |
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131 | * Results: |
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132 | * None. |
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133 | * |
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134 | * Side effects: |
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135 | * None. |
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136 | * |
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137 | *---------------------------------------------------------------------- |
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138 | */ |
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139 | |
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140 | void |
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141 | TclpFree( |
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142 | char *cp) /* Pointer to memory to free. */ |
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143 | { |
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144 | free(cp); |
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145 | return; |
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146 | } |
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147 | |
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148 | /* |
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149 | *---------------------------------------------------------------------- |
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150 | * |
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151 | * TclpRealloc -- |
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152 | * |
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153 | * Reallocate memory. |
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154 | * |
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155 | * Results: |
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156 | * None. |
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157 | * |
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158 | * Side effects: |
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159 | * None. |
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160 | * |
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161 | *---------------------------------------------------------------------- |
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162 | */ |
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163 | |
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164 | char * |
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165 | TclpRealloc( |
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166 | char *cp, /* Pointer to alloced block. */ |
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167 | unsigned int nbytes) /* New size of memory. */ |
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168 | { |
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169 | return (char*) realloc(cp, nbytes); |
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170 | } |
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171 | |
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172 | /* |
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173 | *---------------------------------------------------------------------- |
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174 | * |
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175 | * mstats -- |
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176 | * |
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177 | * Prints two lines of numbers, one showing the length of the |
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178 | * free list for each size category, the second showing the |
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179 | * number of mallocs - frees for each size category. |
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180 | * |
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181 | * Results: |
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182 | * None. |
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183 | * |
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184 | * Side effects: |
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185 | * None. |
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186 | * |
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187 | *---------------------------------------------------------------------- |
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188 | */ |
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189 | |
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190 | #ifdef MSTATS |
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191 | void |
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192 | mstats( |
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193 | char *s) /* Where to write info. */ |
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194 | { |
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195 | register int i, j; |
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196 | register union overhead *p; |
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197 | int totfree = 0, |
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198 | totused = 0; |
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199 | |
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200 | fprintf(stderr, "Memory allocation statistics %s\nTclpFree:\t", s); |
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201 | for (i = 0; i < NBUCKETS; i++) { |
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202 | for (j = 0, p = nextf[i]; p; p = p->ov_next, j++) |
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203 | fprintf(stderr, " %d", j); |
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204 | totfree += j * (1 << (i + 3)); |
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205 | } |
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206 | fprintf(stderr, "\nused:\t"); |
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207 | for (i = 0; i < NBUCKETS; i++) { |
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208 | fprintf(stderr, " %d", nmalloc[i]); |
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209 | totused += nmalloc[i] * (1 << (i + 3)); |
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210 | } |
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211 | fprintf(stderr, "\n\tTotal small in use: %d, total free: %d\n", |
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212 | totused, totfree); |
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213 | fprintf(stderr, "\n\tNumber of big (>%d) blocks in use: %d\n", |
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214 | MAXMALLOC, nmalloc[NBUCKETS]); |
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215 | } |
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216 | #endif |
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217 | |
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