1 | /* |
---|
2 | * Heap Handler |
---|
3 | * |
---|
4 | * COPYRIGHT (c) 1989-1999. |
---|
5 | * On-Line Applications Research Corporation (OAR). |
---|
6 | * |
---|
7 | * The license and distribution terms for this file may be |
---|
8 | * found in the file LICENSE in this distribution or at |
---|
9 | * http://www.OARcorp.com/rtems/license.html. |
---|
10 | * |
---|
11 | * $Id$ |
---|
12 | */ |
---|
13 | |
---|
14 | #if HAVE_CONFIG_H |
---|
15 | #include "config.h" |
---|
16 | #endif |
---|
17 | |
---|
18 | #include <rtems/system.h> |
---|
19 | #include <rtems/score/sysstate.h> |
---|
20 | #include <rtems/score/heap.h> |
---|
21 | |
---|
22 | #if defined(RTEMS_HEAP_DEBUG) |
---|
23 | |
---|
24 | static void |
---|
25 | check_result( |
---|
26 | Heap_Control* the_heap, |
---|
27 | Heap_Block* the_block, |
---|
28 | _H_uptr_t user_addr, |
---|
29 | _H_uptr_t aligned_user_addr, |
---|
30 | uint32_t size) |
---|
31 | { |
---|
32 | _H_uptr_t const user_area = _H_p2u(_Heap_User_area(the_block)); |
---|
33 | _H_uptr_t const block_end = _H_p2u(the_block) |
---|
34 | + _Heap_Block_size(the_block) + HEAP_BLOCK_HEADER_OFFSET; |
---|
35 | _H_uptr_t const user_end = aligned_user_addr + size; |
---|
36 | _H_uptr_t const heap_start = _H_p2u(the_heap->start) + HEAP_OVERHEAD; |
---|
37 | _H_uptr_t const heap_end = _H_p2u(the_heap->final) |
---|
38 | + HEAP_BLOCK_HEADER_OFFSET; |
---|
39 | uint32_t const page_size = the_heap->page_size; |
---|
40 | |
---|
41 | _HAssert(user_addr == user_area); |
---|
42 | _HAssert(aligned_user_addr - user_area < page_size); |
---|
43 | _HAssert(aligned_user_addr >= user_area); |
---|
44 | _HAssert(aligned_user_addr < block_end); |
---|
45 | _HAssert(user_end > user_area); |
---|
46 | _HAssert(user_end <= block_end); |
---|
47 | _HAssert(aligned_user_addr >= heap_start); |
---|
48 | _HAssert(aligned_user_addr < heap_end); |
---|
49 | _HAssert(user_end > heap_start); |
---|
50 | _HAssert(user_end <= heap_end); |
---|
51 | } |
---|
52 | |
---|
53 | #else /* !defined(RTEMS_HEAP_DEBUG) */ |
---|
54 | |
---|
55 | #define check_result(a, b, c, d, e) ((void)0) |
---|
56 | |
---|
57 | #endif /* !defined(RTEMS_HEAP_DEBUG) */ |
---|
58 | |
---|
59 | /*PAGE |
---|
60 | * |
---|
61 | * _Heap_Allocate_aligned |
---|
62 | * |
---|
63 | * This kernel routine allocates the requested size of memory |
---|
64 | * from the specified heap so that returned address is aligned according to |
---|
65 | * the 'alignment'. |
---|
66 | * |
---|
67 | * Input parameters: |
---|
68 | * the_heap - pointer to the heap control block. |
---|
69 | * size - size in bytes of the memory block to allocate. |
---|
70 | * alignment - required user pointer alignment in bytes |
---|
71 | * |
---|
72 | * Output parameters: |
---|
73 | * returns - starting address of memory block allocated. The address is |
---|
74 | * aligned on specified boundary. |
---|
75 | */ |
---|
76 | |
---|
77 | void *_Heap_Allocate_aligned( |
---|
78 | Heap_Control *the_heap, |
---|
79 | size_t size, |
---|
80 | uint32_t alignment |
---|
81 | ) |
---|
82 | { |
---|
83 | uint32_t search_count; |
---|
84 | Heap_Block *the_block; |
---|
85 | |
---|
86 | void *user_ptr = NULL; |
---|
87 | uint32_t const page_size = the_heap->page_size; |
---|
88 | Heap_Statistics *const stats = &the_heap->stats; |
---|
89 | Heap_Block *const tail = _Heap_Tail(the_heap); |
---|
90 | |
---|
91 | uint32_t const end_to_user_offs = size - HEAP_BLOCK_HEADER_OFFSET; |
---|
92 | |
---|
93 | uint32_t const the_size = |
---|
94 | _Heap_Calc_block_size(size, page_size, the_heap->min_block_size); |
---|
95 | |
---|
96 | if(the_size == 0) |
---|
97 | return NULL; |
---|
98 | |
---|
99 | if(alignment == 0) |
---|
100 | alignment = CPU_ALIGNMENT; |
---|
101 | |
---|
102 | /* Find large enough free block that satisfies the alignment requirements. */ |
---|
103 | |
---|
104 | for(the_block = _Heap_Head(the_heap)->next, search_count = 0; |
---|
105 | the_block != tail; |
---|
106 | the_block = the_block->next, ++search_count) |
---|
107 | { |
---|
108 | uint32_t const block_size = _Heap_Block_size(the_block); |
---|
109 | |
---|
110 | /* As we always coalesce free blocks, prev block must have been used. */ |
---|
111 | _HAssert(_Heap_Is_prev_used(the_block)); |
---|
112 | |
---|
113 | if(block_size >= the_size) { /* the_block is large enough. */ |
---|
114 | |
---|
115 | _H_uptr_t user_addr; |
---|
116 | _H_uptr_t aligned_user_addr; |
---|
117 | _H_uptr_t const user_area = _H_p2u(_Heap_User_area(the_block)); |
---|
118 | |
---|
119 | /* Calculate 'aligned_user_addr' that will become the user pointer we |
---|
120 | return. It should be at least 'end_to_user_offs' bytes less than the |
---|
121 | the 'block_end' and should be aligned on 'alignment' boundary. |
---|
122 | Calculations are from the 'block_end' as we are going to split free |
---|
123 | block so that the upper part of the block becomes used block. */ |
---|
124 | _H_uptr_t const block_end = _H_p2u(the_block) + block_size; |
---|
125 | aligned_user_addr = block_end - end_to_user_offs; |
---|
126 | _Heap_Align_down_uptr(&aligned_user_addr, alignment); |
---|
127 | |
---|
128 | /* 'user_addr' is the 'aligned_user_addr' further aligned down to the |
---|
129 | 'page_size' boundary. We need it as blocks' user areas should begin |
---|
130 | only at 'page_size' aligned addresses */ |
---|
131 | user_addr = aligned_user_addr; |
---|
132 | _Heap_Align_down_uptr(&user_addr, page_size); |
---|
133 | |
---|
134 | /* Make sure 'user_addr' calculated didn't run out of 'the_block. */ |
---|
135 | if(user_addr >= user_area) { |
---|
136 | |
---|
137 | /* The block seems to be acceptable. Check if the remainder of |
---|
138 | 'the_block' is less than 'min_block_size' so that 'the_block' won't |
---|
139 | actually be split at the address we assume. */ |
---|
140 | if(user_addr - user_area < the_heap->min_block_size) { |
---|
141 | |
---|
142 | /* The block won't be split, so 'user_addr' will be equal to the |
---|
143 | 'user_area'. */ |
---|
144 | user_addr = user_area; |
---|
145 | |
---|
146 | /* We can't allow the distance between 'user_addr' and |
---|
147 | 'aligned_user_addr' to be outside of [0,page_size) range. If we do, |
---|
148 | we will need to store this distance somewhere to be able to |
---|
149 | resurrect the block address from the user pointer. (Having the |
---|
150 | distance within [0,page_size) range allows resurrection by |
---|
151 | aligning user pointer down to the nearest 'page_size' boundary.) */ |
---|
152 | if(aligned_user_addr - user_addr >= page_size) { |
---|
153 | |
---|
154 | /* The user pointer will be too far from 'user_addr'. See if we |
---|
155 | can make 'aligned_user_addr' to be close enough to the |
---|
156 | 'user_addr'. */ |
---|
157 | aligned_user_addr = user_addr; |
---|
158 | _Heap_Align_up_uptr(&aligned_user_addr, alignment); |
---|
159 | if(aligned_user_addr - user_addr >= page_size) { |
---|
160 | /* No, we can't use the block */ |
---|
161 | aligned_user_addr = 0; |
---|
162 | } |
---|
163 | } |
---|
164 | } |
---|
165 | |
---|
166 | if(aligned_user_addr) { |
---|
167 | |
---|
168 | /* The block is indeed acceptable: calculate the size of the block |
---|
169 | to be allocated and perform allocation. */ |
---|
170 | uint32_t const alloc_size = |
---|
171 | block_end - user_addr + HEAP_BLOCK_USER_OFFSET; |
---|
172 | |
---|
173 | _HAssert(_Heap_Is_aligned_ptr((void*)aligned_user_addr, alignment)); |
---|
174 | |
---|
175 | (void)_Heap_Block_allocate(the_heap, the_block, alloc_size); |
---|
176 | |
---|
177 | stats->searches += search_count + 1; |
---|
178 | stats->allocs += 1; |
---|
179 | |
---|
180 | check_result(the_heap, the_block, user_addr, |
---|
181 | aligned_user_addr, size); |
---|
182 | |
---|
183 | user_ptr = (void*)aligned_user_addr; |
---|
184 | break; |
---|
185 | } |
---|
186 | } |
---|
187 | } |
---|
188 | } |
---|
189 | |
---|
190 | if(stats->max_search < search_count) |
---|
191 | stats->max_search = search_count; |
---|
192 | |
---|
193 | return user_ptr; |
---|
194 | } |
---|