[176] | 1 | /* -*- C++ -*- */ |
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| 2 | |
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| 3 | /** |
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| 4 | * @class ZoneHeap |
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| 5 | * @brief A zone (or arena, or region) based allocator. |
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| 6 | * @author Emery Berger |
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| 7 | * @date June 2000 |
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| 8 | * |
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| 9 | * Uses the superclass to obtain large chunks of memory that are only |
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| 10 | * returned when the heap itself is destroyed. |
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| 11 | * |
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| 12 | */ |
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| 13 | |
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| 14 | #ifndef _ZONEHEAP_H_ |
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| 15 | #define _ZONEHEAP_H_ |
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| 16 | |
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| 17 | #include <assert.h> |
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| 18 | |
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| 19 | namespace HL { |
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| 20 | |
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| 21 | template <class Super, size_t ChunkSize> |
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| 22 | class ZoneHeap : public Super { |
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| 23 | public: |
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| 24 | |
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| 25 | ZoneHeap (void) |
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| 26 | : sizeRemaining (-1), |
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| 27 | currentArena (NULL), |
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| 28 | pastArenas (NULL) |
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| 29 | {} |
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| 30 | |
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| 31 | ~ZoneHeap (void) |
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| 32 | { |
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| 33 | // printf ("deleting arenas!\n"); |
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| 34 | // Delete all of our arenas. |
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| 35 | Arena * ptr = pastArenas; |
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| 36 | while (ptr != NULL) { |
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| 37 | void * oldPtr = (void *) ptr; |
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| 38 | ptr = ptr->nextArena; |
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| 39 | //printf ("deleting %x\n", ptr); |
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| 40 | Super::free (oldPtr); |
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| 41 | } |
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| 42 | if (currentArena != NULL) |
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| 43 | //printf ("deleting %x\n", currentArena); |
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| 44 | Super::free (currentArena); |
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| 45 | } |
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| 46 | |
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| 47 | inline void * malloc (size_t sz) { |
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| 48 | void * ptr = zoneMalloc (sz); |
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| 49 | return ptr; |
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| 50 | } |
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| 51 | |
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| 52 | /// Free in a zone allocator is a no-op. |
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| 53 | inline void free (void *) {} |
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| 54 | |
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| 55 | /// Remove in a zone allocator is a no-op. |
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| 56 | inline int remove (void *) { return 0; } |
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| 57 | |
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| 58 | |
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| 59 | private: |
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| 60 | |
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| 61 | inline static size_t align (int sz) { |
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| 62 | return (sz + (sizeof(double) - 1)) & ~(sizeof(double) - 1); |
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| 63 | } |
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| 64 | |
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| 65 | inline void * zoneMalloc (size_t sz) { |
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| 66 | void * ptr; |
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| 67 | // Round up size to an aligned value. |
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| 68 | sz = align (sz); |
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| 69 | // Get more space in our arena if there's not enough room in this one. |
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| 70 | if ((currentArena == NULL) || (sizeRemaining < (int) sz)) { |
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| 71 | // First, add this arena to our past arena list. |
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| 72 | if (currentArena != NULL) { |
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| 73 | currentArena->nextArena = pastArenas; |
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| 74 | pastArenas = currentArena; |
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| 75 | } |
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| 76 | // Now get more memory. |
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| 77 | size_t allocSize = ChunkSize; |
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| 78 | if (allocSize < sz) { |
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| 79 | allocSize = sz; |
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| 80 | } |
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| 81 | currentArena = |
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| 82 | (Arena *) Super::malloc (allocSize + sizeof(Arena)); |
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| 83 | if (currentArena == NULL) { |
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| 84 | return NULL; |
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| 85 | } |
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| 86 | currentArena->arenaSpace = (char *) (currentArena + 1); |
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| 87 | currentArena->nextArena = NULL; |
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| 88 | sizeRemaining = ChunkSize; |
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| 89 | } |
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| 90 | // Bump the pointer and update the amount of memory remaining. |
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| 91 | sizeRemaining -= sz; |
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| 92 | ptr = currentArena->arenaSpace; |
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| 93 | currentArena->arenaSpace += sz; |
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| 94 | assert (ptr != NULL); |
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| 95 | return ptr; |
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| 96 | } |
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| 97 | |
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| 98 | class Arena { |
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| 99 | public: |
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| 100 | Arena * nextArena; |
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| 101 | char * arenaSpace; |
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| 102 | double _dummy; // For alignment. |
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| 103 | }; |
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| 104 | |
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| 105 | /// Space left in the current arena. |
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| 106 | long sizeRemaining; |
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| 107 | |
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| 108 | /// The current arena. |
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| 109 | Arena * currentArena; |
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| 110 | |
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| 111 | /// A linked list of past arenas. |
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| 112 | Arena * pastArenas; |
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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 | #endif |
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