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/****************************************************************************
* fs/mmap/rammap.h
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* References: Linux/Documentation/filesystems/romfs.txt
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
#ifndef __FS_MMAP_RAMMAP_H
#define __FS_MMAP_RAMMAP_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <semaphore.h>
#ifdef CONFIG_FS_RAMMAP
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Public Types
****************************************************************************/
/* This structure describes one file that has been copied to memory and
* managed as a share-able "memory mapped" file. This functionality is
* intended to provide a substitute for memory mapped files for architectures
* that do not have MMUs and, hence, cannot support on demand paging of
* blocks of a file.
*
* This copied file has many of the properties of a standard memory mapped
* file except:
*
* - All of the file must be present in memory. This limits the size of
* files that may be memory mapped (especially on MCUs with no significant
* RAM resources).
* - All mapped files are read-only. You can write to the in-memory image,
* but the file contents will not change.
* - There are not access privileges.
*/
struct fs_rammap_s
{
struct fs_rammap_s *flink; /* Implements a singly linked list */
FAR void *addr; /* Start of allocated memory */
size_t length; /* Length of region */
off_t offset; /* File offset */
};
/* This structure defines all "mapped" files */
struct fs_allmaps_s
{
bool initialized; /* True: This structure has been initialized */
sem_t exclsem; /* Provides exclusive access the list */
struct fs_rammap_s *head; /* List of mapped files */
};
/****************************************************************************
* Public Variables
****************************************************************************/
/* This is the list of all mapped files */
extern struct fs_allmaps_s g_rammaps;
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
/****************************************************************************
* Name: rammap_initialize
*
* Description:
* Verified that this capability has been initialized.
*
* Input Parameters:
* None
*
* Returned Value:
* None
*
****************************************************************************/
extern void rammap_initialize(void);
/****************************************************************************
* Name: rammmap
*
* Description:
* Support simulation of memory mapped files by copying files into RAM.
*
* Parameters:
* fd file descriptor of the backing file -- required.
* length The length of the mapping. For exception #1 above, this length
* ignored: The entire underlying media is always accessible.
* offset The offset into the file to map
*
* Returned Value:
* On success, rammmap() returns a pointer to the mapped area. On error, the
* value MAP_FAILED is returned, and errno is set appropriately.
*
* EBADF
* 'fd' is not a valid file descriptor.
* EINVAL
* 'length' or 'offset' are invalid
* ENOMEM
* Insufficient memory is available to map the file.
*
****************************************************************************/
extern FAR void *rammap(int fd, size_t length, off_t offset);
#endif /* CONFIG_FS_RAMMAP */
#endif /* __FS_MMAP_RAMMAP_H */
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