1 | /* -*- C++ -*- */ |
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2 | |
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3 | #ifndef _CHUNKHEAP_H_ |
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4 | #define _CHUNKHEAP_H_ |
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5 | |
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6 | /* |
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7 | |
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8 | Heap Layers: An Extensible Memory Allocation Infrastructure |
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9 | |
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10 | Copyright (C) 2000-2003 by Emery Berger |
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11 | http://www.cs.umass.edu/~emery |
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12 | emery@cs.umass.edu |
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13 | |
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14 | This program is free software; you can redistribute it and/or modify |
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15 | it under the terms of the GNU General Public License as published by |
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16 | the Free Software Foundation; either version 2 of the License, or |
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17 | (at your option) any later version. |
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18 | |
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19 | This program is distributed in the hope that it will be useful, |
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20 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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21 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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22 | GNU General Public License for more details. |
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23 | |
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24 | You should have received a copy of the GNU General Public License |
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25 | along with this program; if not, write to the Free Software |
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26 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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27 | |
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28 | */ |
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29 | |
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30 | #include <assert.h> |
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31 | |
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32 | /** |
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33 | * @class ChunkHeap |
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34 | * @brief Allocates memory from the superheap in chunks. |
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35 | * @param ChunkSize The minimum size for allocating memory from the superheap. |
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36 | */ |
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37 | |
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38 | namespace HL { |
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39 | |
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40 | template <int ChunkSize, class SuperHeap> |
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41 | class ChunkHeap : public SuperHeap { |
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42 | public: |
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43 | |
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44 | inline ChunkHeap (void) |
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45 | : buffer (NULL), |
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46 | eob (NULL) |
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47 | {} |
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48 | |
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49 | inline void * malloc (const size_t sz) { |
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50 | void * ptr = buffer; |
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51 | buffer += sz; |
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52 | if (buffer <= eob) { |
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53 | assert (eob != NULL); |
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54 | assert ((size_t) (eob - (char *) ptr + 1) >= sz); |
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55 | return ptr; |
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56 | } |
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57 | buffer -= sz; // we didn't succeed, back up |
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58 | return getMoreMemory(sz); |
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59 | } |
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60 | |
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61 | inline void clear (void) { |
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62 | buffer = NULL; |
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63 | eob = NULL; |
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64 | SuperHeap::clear (); |
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65 | } |
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66 | |
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67 | private: |
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68 | |
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69 | // Disabled. |
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70 | inline int remove (void *); |
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71 | |
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72 | void * getMoreMemory (size_t sz) { |
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73 | assert (sz > 0); |
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74 | // Round sz to the next chunk size. |
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75 | size_t reqSize = (((sz-1) / ChunkSize) + 1) * ChunkSize; |
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76 | char * buf = (char *) SuperHeap::malloc (reqSize); |
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77 | if (buf == NULL) { |
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78 | return NULL; |
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79 | } |
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80 | // If the current end of buffer is not the same as the new buffer, |
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81 | // reset the buffer pointer. |
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82 | if (eob != buf) { |
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83 | buffer = buf; |
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84 | } |
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85 | else { |
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86 | // we still have a bit leftover at the end of previous buffer |
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87 | reqSize += eob - buffer; |
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88 | } |
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89 | eob = buffer + reqSize; |
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90 | |
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91 | void * ptr = buffer; |
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92 | buffer += sz; |
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93 | return ptr; |
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94 | } |
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95 | |
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96 | /// The current allocation buffer. |
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97 | char * buffer; |
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98 | |
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99 | /// The end of the buffer. |
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100 | char * eob; |
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101 | }; |
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102 | |
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103 | } |
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104 | |
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105 | #endif |
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