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1 | /* -*- C++ -*- */ |
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2 | |
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3 | #ifndef _FIFOFREELIST_H_ |
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4 | #define _FIFOFREELIST_H_ |
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5 | |
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6 | #include <assert.h> |
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7 | |
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8 | #ifdef NDEBUG |
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9 | #define IFDEBUG(x) |
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10 | #else |
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11 | #define IFDEBUG(x) x |
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12 | #endif |
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13 | |
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14 | |
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15 | template <class SuperHeap> |
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16 | class FIFOFreelistHeap : public SuperHeap { |
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17 | public: |
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18 | |
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19 | FIFOFreelistHeap (void) |
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20 | IFDEBUG(: nObjects (0)) |
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21 | { |
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22 | head.next = &tail; |
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23 | tail.next = &tail; |
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24 | assert (isEmpty()); |
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25 | } |
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26 | |
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27 | ~FIFOFreelistHeap (void) |
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28 | { |
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29 | // printf ("Adios free list.\n"); |
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30 | // Delete everything on the free list. |
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31 | freeObject * ptr = head.next; |
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32 | while (ptr != &tail) { |
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33 | void * oldptr = ptr; |
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34 | ptr = ptr->next; |
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35 | SuperHeap::free (oldptr); |
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36 | } |
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37 | } |
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38 | |
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39 | inline void * malloc (size_t sz) { |
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40 | assert (isValid()); |
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41 | // Check the free list first. |
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42 | freeObject * ptr = head.next; |
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43 | if (ptr == &tail) { |
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44 | assert (nObjects == 0); |
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45 | assert (isEmpty()); |
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46 | ptr = (freeObject *) SuperHeap::malloc (sz); |
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47 | } else { |
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48 | assert (nObjects > 0); |
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49 | head.next = ptr->next; |
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50 | if (head.next == &tail) { |
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51 | tail.next = &tail; |
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52 | } |
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53 | IFDEBUG (nObjects--); |
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54 | } |
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55 | assert (isValid()); |
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56 | return (void *) ptr; |
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57 | } |
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58 | |
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59 | inline void free (void * ptr) { |
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60 | assert (isValid()); |
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61 | // Add this object to the free list. |
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62 | assert (ptr != NULL); |
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63 | IFDEBUG (nObjects++); |
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64 | freeObject * p = (freeObject *) ptr; |
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65 | p->next = &tail; |
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66 | tail.next->next = p; |
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67 | tail.next = p; |
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68 | if (head.next == &tail) { |
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69 | head.next = p; |
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70 | } |
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71 | assert (!isEmpty()); |
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72 | assert (isValid()); |
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73 | } |
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74 | |
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75 | private: |
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76 | |
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77 | int isValid (void) { |
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78 | // Make sure every object is the right size. |
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79 | freeObject * ptr = head.next; |
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80 | if (ptr != &tail) { |
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81 | size_t sz = SuperHeap::getSize(ptr); |
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82 | while (ptr != &tail) { |
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83 | void * oldptr = ptr; |
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84 | ptr = ptr->next; |
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85 | assert (SuperHeap::getSize(oldptr) >= sz); |
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86 | } |
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87 | } |
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88 | return 1; |
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89 | } |
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90 | |
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91 | int isEmpty (void) { |
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92 | return (head.next == &tail); |
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93 | } |
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94 | |
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95 | class freeObject { |
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96 | public: |
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97 | freeObject * prev; |
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98 | freeObject * next; |
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99 | }; |
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100 | |
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101 | freeObject head, tail; |
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102 | IFDEBUG (int nObjects); |
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103 | }; |
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104 | |
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105 | #endif |
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