1 | /* |
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2 | * Heap Handler |
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3 | * |
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4 | * COPYRIGHT (c) 1989-1999. |
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5 | * On-Line Applications Research Corporation (OAR). |
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6 | * |
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7 | * The license and distribution terms for this file may be |
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8 | * found in the file LICENSE in this distribution or at |
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9 | * http://www.rtems.com/license/LICENSE. |
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10 | * |
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11 | * $Id$ |
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12 | */ |
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13 | |
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14 | #if HAVE_CONFIG_H |
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15 | #include "config.h" |
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16 | #endif |
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17 | |
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18 | #include <rtems/system.h> |
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19 | #include <rtems/score/sysstate.h> |
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20 | #include <rtems/score/heap.h> |
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21 | |
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22 | /*PAGE |
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23 | * |
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24 | * _Heap_Allocate |
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25 | * |
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26 | * This kernel routine allocates the requested size of memory |
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27 | * from the specified heap. |
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28 | * |
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29 | * Input parameters: |
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30 | * the_heap - pointer to heap header. |
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31 | * size - size in bytes of the memory block to allocate. |
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32 | * |
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33 | * Output parameters: |
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34 | * returns - starting address of memory block allocated |
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35 | */ |
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36 | |
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37 | void *_Heap_Allocate( |
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38 | Heap_Control *the_heap, |
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39 | uint32_t size |
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40 | ) |
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41 | { |
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42 | uint32_t the_size; |
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43 | uint32_t search_count; |
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44 | Heap_Block *the_block; |
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45 | void *ptr = NULL; |
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46 | Heap_Statistics *const stats = &the_heap->stats; |
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47 | Heap_Block *const tail = _Heap_Tail(the_heap); |
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48 | |
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49 | the_size = |
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50 | _Heap_Calc_block_size(size, the_heap->page_size, the_heap->min_block_size); |
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51 | if(the_size == 0) |
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52 | return NULL; |
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53 | |
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54 | /* Find large enough free block. */ |
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55 | for(the_block = _Heap_First(the_heap), search_count = 0; |
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56 | the_block != tail; |
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57 | the_block = the_block->next, ++search_count) |
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58 | { |
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59 | /* As we always coalesce free blocks, prev block must have been used. */ |
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60 | _HAssert(_Heap_Is_prev_used(the_block)); |
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61 | |
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62 | /* Don't bother to mask out the HEAP_PREV_USED bit as it won't change the |
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63 | result of the comparison. */ |
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64 | if(the_block->size >= the_size) { |
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65 | (void)_Heap_Block_allocate(the_heap, the_block, the_size ); |
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66 | |
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67 | ptr = _Heap_User_area(the_block); |
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68 | |
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69 | stats->allocs += 1; |
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70 | stats->searches += search_count + 1; |
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71 | |
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72 | _HAssert(_Heap_Is_aligned_ptr(ptr, the_heap->page_size)); |
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73 | break; |
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74 | } |
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75 | } |
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76 | |
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77 | if(stats->max_search < search_count) |
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78 | stats->max_search = search_count; |
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79 | |
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80 | return ptr; |
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81 | } |
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