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