fs_port.h

UCOS操作系统的文件系统开发实例,有兴趣的可以

/*
**********************************************************************
*                          Micrium, Inc.
*                      949 Crestview Circle
*                     Weston,  FL 33327-1848
*
*                            uC/FS
*
*                (c) Copyright 2002, Micrium, Inc.
*                      All rights reserved.
*
***********************************************************************

----------------------------------------------------------------------
File        : fs_port.h 
Purpose     : Architecture dependend defines for the file system
              This header defines basic data types and access macros
              used by the file system. Depending on your CPU/compiler,
              you may have to modify this file.
----------------------------------------------------------------------
Known problems or limitations with current version
----------------------------------------------------------------------
None.
---------------------------END-OF-HEADER------------------------------
*/

#ifndef _FS_PORT_H_
#define _FS_PORT_H_

/*********************************************************************
*
*             #define constants
*
**********************************************************************
*/

#define FS_LITTLE_ENDIAN      1     /* 1 = little endian, 0 = big endian */


/*********************************************************************
*
*             define global data types
*
**********************************************************************

  These defines will work for most 8/16/32 bit CPUs. Please check
  your compiler manual if you are not sure.
*/

#define FS_size_t       unsigned long       /* 32 bit unsigned */
#define FS_u32          unsigned long       /* 32 bit unsigned */
#define FS_i32          signed long         /* 32 bit signed */
#define FS_u16          unsigned short      /* 16 bit unsigned */
#define FS_i16          signed short        /* 16 bit signed */

/* 
  Some CPUs have default character pointers, which are unable to access
  the complete CPU address space. The following define is used for character
  pointers, which must be able to access the complete address space.
*/
#define FS_FARCHARPTR   char *              /* far character pointer */


/*********************************************************************
*
*             #define access macros
*
**********************************************************************

  Following macros are used to access data of a FAT file system.
  Systems using little endian can access data as it is, but big
  endian systems have to swap.
*/

#if (FS_LITTLE_ENDIAN==1)
#define FS__r_u32(value)   value
#define FS__w_u32(value)   value
#define FS__r_u16(value)   value
#define FS__w_u16(value)   value
#else
#define FS__r_u32(value)   ((value >> 24) | (value << 24) | ((value & 0x00ff0000ul) >> 8) | ((value & 0x0000ff00ul) << 8))
#define FS__w_u32(value)   FS__r_u32(value) 
#define FS__r_u16(value)   ( ((FS_u16)(value>>8) | (FS_u16)(value<<8)) )
#define FS__w_u16(value)   FS__r_u16(value)
#endif

#endif  /* _FS_PORT_H_ */