4 * @copyright Copyright (C) 2016 Sproute Networks, Inc.
6 * @author Avneesh Sachdev <avneesh@sproute.com>
8 * This file is part of Quagga.
10 * Quagga is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the
12 * Free Software Foundation; either version 2, or (at your option) any
15 * Quagga is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * General Public License for more details.
20 * You should have received a copy of the GNU General Public License along
21 * with this program; see the file COPYING; if not, write to the Free Software
22 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
26 * Header file for the linear allocator.
28 * An allocator that allocates memory by walking down towards the end
29 * of a buffer. No attempt is made to reuse blocks that are freed
30 * subsequently. The assumption is that the buffer is big enough to
31 * cover allocations for a given purpose.
39 * Alignment for block allocated by the allocator. Must be a power of 2.
41 #define LINEAR_ALLOCATOR_ALIGNMENT 8
43 #define LINEAR_ALLOCATOR_ALIGN(value) \
44 (((value) + LINEAR_ALLOCATOR_ALIGNMENT - 1) \
45 & ~(LINEAR_ALLOCATOR_ALIGNMENT - 1));
48 * linear_allocator_align_ptr
50 static inline char *linear_allocator_align_ptr(char *ptr
)
52 return (char *)LINEAR_ALLOCATOR_ALIGN((intptr_t)ptr
);
55 typedef struct linear_allocator_t_
{
59 * Current location in the buffer.
69 * Version number of the allocator, this is bumped up when the allocator
70 * is reset and helps identifies bad frees.
75 * The number of blocks that are currently allocated.
81 * linear_allocator_block_t
83 * Header structure at the begining of each block.
85 typedef struct linear_allocator_block_t_
{
89 * The version of the allocator when this block was allocated.
93 } linear_allocator_block_t
;
95 #define LINEAR_ALLOCATOR_BLOCK_IN_USE 0x01
97 #define LINEAR_ALLOCATOR_HDR_SIZE (sizeof(linear_allocator_block_t))
100 * linear_allocator_block_size
102 * The total amount of space a block will take in the buffer,
103 * including the size of the header.
105 static inline size_t linear_allocator_block_size(size_t user_size
)
107 return LINEAR_ALLOCATOR_ALIGN(LINEAR_ALLOCATOR_HDR_SIZE
+ user_size
);
111 * linear_allocator_ptr_to_block
113 static inline linear_allocator_block_t
*linear_allocator_ptr_to_block(void *ptr
)
116 block_ptr
= ((char *)ptr
) - offsetof(linear_allocator_block_t
, data
);
121 * linear_allocator_init
123 static inline void linear_allocator_init(linear_allocator_t
*allocator
,
124 char *buf
, size_t buf_len
)
126 memset(allocator
, 0, sizeof(*allocator
));
128 assert(linear_allocator_align_ptr(buf
) == buf
);
129 allocator
->buf
= buf
;
130 allocator
->cur
= buf
;
131 allocator
->end
= buf
+ buf_len
;
135 * linear_allocator_reset
137 * Prepare an allocator for reuse.
139 * *** NOTE ** This implicitly frees all the blocks in the allocator.
141 static inline void linear_allocator_reset(linear_allocator_t
*allocator
)
143 allocator
->num_allocated
= 0;
144 allocator
->version
++;
145 allocator
->cur
= allocator
->buf
;
149 * linear_allocator_alloc
151 static inline void *linear_allocator_alloc(linear_allocator_t
*allocator
,
155 linear_allocator_block_t
*block
;
157 block_size
= linear_allocator_block_size(user_size
);
159 if (allocator
->cur
+ block_size
> allocator
->end
) {
163 block
= (linear_allocator_block_t
*)allocator
->cur
;
164 allocator
->cur
+= block_size
;
166 block
->flags
= LINEAR_ALLOCATOR_BLOCK_IN_USE
;
167 block
->version
= allocator
->version
;
168 allocator
->num_allocated
++;
173 * linear_allocator_free
175 static inline void linear_allocator_free(linear_allocator_t
*allocator
,
178 linear_allocator_block_t
*block
;
180 if (((char *)ptr
) < allocator
->buf
|| ((char *)ptr
) >= allocator
->end
) {
185 block
= linear_allocator_ptr_to_block(ptr
);
186 if (block
->version
!= allocator
->version
) {
191 block
->flags
= block
->flags
& ~LINEAR_ALLOCATOR_BLOCK_IN_USE
;
193 if (--allocator
->num_allocated
< 0) {