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Diffstat (limited to 'nuttx/fs/mmap/fs_rammap.h')
-rw-r--r-- | nuttx/fs/mmap/fs_rammap.h | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/nuttx/fs/mmap/fs_rammap.h b/nuttx/fs/mmap/fs_rammap.h new file mode 100644 index 000000000..9076d7343 --- /dev/null +++ b/nuttx/fs/mmap/fs_rammap.h @@ -0,0 +1,150 @@ +/**************************************************************************** + * 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 */ |