71 lines
2.6 KiB
C
71 lines
2.6 KiB
C
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/*
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** Copyright 2002/03, Thomas Kurschel. All rights reserved.
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** Distributed under the terms of the OpenBeOS License.
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*/
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/*
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Paging-safe allocation of locked memory.
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Library for managing temporary, locked memory with the condition of
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not calling any function during allocation that can lead to paging.
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Such memory is needed by drivers that are used to access the page file
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but still need locked memory to execute requests.
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Basically, a background thread manages a memory pool where blocks
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are allocated from. If the pool is empty, allocation is delayed until
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either a blocks is freed or the pool is enlarged by the background
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thread.
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All memory blocks must have same size and can be pre-initialized when
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added to memory pool (and cleaned-up when removed from pool). The
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free list is stored within free memory blocks, so you have to specify
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a block offset where the manager can store the list pointers without
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interfering with pre-initialization.
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You can also specify an alignment, e.g. if the blocks are used for
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DMA access, a minimum pool size (in blocks), a maximum pool size
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(in blocks) and the size of memory chunks to be added if the entire
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pool is allocated.
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*/
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#ifndef __LOCKED_POOL_H__
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#define __LOCKED_POOL_H__
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#include <device_manager.h>
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typedef struct locked_pool *locked_pool_cookie;
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typedef status_t (*locked_pool_add_hook)(void *block, void *arg);
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typedef void (*locked_pool_remove_hook)(void *block, void *arg);
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typedef struct {
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module_info minfo;
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// allocate block
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void *(*alloc)(locked_pool_cookie pool);
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// free block
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void (*free)(locked_pool_cookie pool, void *block);
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// create new pool
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// block_size - size of one memory block
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// alignment - set address bits here that must be zero for block addresses
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// next_ofs - offset in block where internal next-pointer can be stored
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// chunk_size - how much system memory is to be allocated at once
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// max_blocks - maximum number of blocks
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// min_free_block - minimum number of free blocks
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// name - name of pool
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// lock_flags - flags to be passed to lock_memory()
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// alloc_hook - hook to be called when new block is added to pool (can be NULL )
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// free_hook - hook to be called when block is removed from pool (can be NULL )
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// hook_arg - value to be passed to hooks as arg
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locked_pool_cookie (*create)(int block_size, int alignment, int next_ofs,
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int chunk_size, int max_blocks, int min_free_blocks, const char *name,
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uint32 lock_flags, locked_pool_add_hook add_hook,
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locked_pool_remove_hook remove_hook, void *hook_arg);
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void (*destroy)(locked_pool_cookie pool);
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} locked_pool_interface;
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#define LOCKED_POOL_MODULE_NAME "generic/locked_pool/v1"
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#endif
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