[176] | 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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