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[176] | 1 | #ifndef _THEAP_H_ |
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| 2 | #define _THEAP_H_ |
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| 3 | |
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| 4 | // A general threshold-based heap. |
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| 5 | |
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| 6 | // Threshold layer. |
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| 7 | // Once we have more than Threshold bytes on our freelist, |
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| 8 | // return memory to the superheap. |
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| 9 | |
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| 10 | // The class argument FH should be some freelist heap that subclasses NullHeap. |
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| 11 | |
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| 12 | template <class SuperHeap, class FH, int Threshold> |
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| 13 | class THeap : public SuperHeap { |
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| 14 | public: |
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| 15 | THeap (void) |
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| 16 | : total (0) |
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| 17 | {} |
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| 18 | |
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| 19 | ~THeap (void) |
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| 20 | {} |
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| 21 | |
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| 22 | inline void * malloc (size_t sz) { |
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| 23 | void * ptr; |
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| 24 | ptr = fHeap.malloc (sz); |
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| 25 | if (ptr == NULL) { |
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| 26 | // We have no memory on our freelist. |
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| 27 | // Get it from the superheap. |
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| 28 | ptr = SuperHeap::malloc (sz); |
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| 29 | } else { |
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| 30 | total -= size(ptr); |
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| 31 | // printf ("total = %d\n", total); |
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| 32 | } |
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| 33 | assert (size(ptr) >= sz); |
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| 34 | return ptr; |
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| 35 | } |
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| 36 | |
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| 37 | inline void free (void * ptr) { |
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| 38 | if (total < Threshold) { |
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| 39 | // printf ("FREE TO FREELIST.\n"); |
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| 40 | total += size(ptr); |
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| 41 | fHeap.free (ptr); |
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| 42 | //printf ("total = %d\n", total); |
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| 43 | } else { |
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| 44 | // Dump the freelist heap. |
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| 45 | void * p = fHeap.malloc (1); |
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| 46 | while (p != NULL) { |
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| 47 | SuperHeap::free (p); |
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| 48 | p = fHeap.malloc (1); |
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| 49 | } |
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| 50 | SuperHeap::free (ptr); |
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| 51 | total = 0; |
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| 52 | } |
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| 53 | } |
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| 54 | |
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| 55 | private: |
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| 56 | // Provide a free list that will return NULL if it is out of memory. |
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| 57 | FH fHeap; |
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| 58 | int total; |
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| 59 | }; |
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| 60 | |
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| 61 | |
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| 62 | #endif |
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