LibrePilot/flight/Libraries/dosfs/dfs_sdcard.c

/**
 ******************************************************************************
 *
 * @file       pios.c
 * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2009.
 * @brief      Access layer between DOSFS and PIOS
 * @see        The GNU Public License (GPL) Version 3
 *
 *****************************************************************************/
/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

/* Include files */

#include <pios.h>

#include "dosfs.h"


/* Local variables */

/* For caching - this feature has to be explicitly enabled, as it isn't reentrant */
/* and requires to use the same buffer pointer whenever reading a file. */
static uint32_t last_sector;
static uint8_t caching_enabled   = 0;

void DFS_CachingEnabledSet(uint8_t enable)
{
	caching_enabled = enable;
	last_sector = 0xffffffff;
}


/**
* Converts directory name to canonical name
* (missing pendant to DFS_anonicalToDir)
* dest must point to a 13-byte buffer
*/
char *DFS_DirToCanonical(char *dest, char *src)
{
	uint8_t pos = 0;

	while( pos < 8 && src[pos] != ' ' ) {
		*dest++ = src[pos++];
	}

	if( src[8] != ' ' ) {
		*dest++ = '.';

		pos = 8;
		while( pos < 11 && src[pos] != ' ' ) {
			*dest++ = src[pos++];
		}
	}

	/* Terminate string */
	*dest = 0;

	return dest;
}



/**
* Read sector from SD Card
* Returns 0 OK, nonzero for any error
*/
uint32_t DFS_ReadSector(uint8_t unit, uint8_t *buffer, uint32_t sector, uint32_t count)
{
	/* Only allow access to single unit */
	if(unit != 0) {
		return 1;
	}

	/* According to README.txt, count is always 1 - check this! */
	if(count != 1) {
		return 2;
	}

	/* Cache: */
	if(caching_enabled && sector == last_sector) {
		/* we assume that sector is already in *buffer */
		/* since the user has to take care that the same buffer is used for file reads, this */
		/* feature has to be explicitly enabled with DFS_CachingEnabledSet(uint8_t enable) */
		return 0;
	}

	last_sector = sector;

	/* Forward to PIOS */
	int32_t status;
	if((status = PIOS_SDCARD_SectorRead(sector, buffer)) < 0) {
		/* Cannot access SD Card */
		return 3;
	}

	/* Success */
	return 0;
}

/**
* Write sector to SD Card
* Returns 0 OK, nonzero for any error
*/
uint32_t DFS_WriteSector(uint8_t unit, uint8_t *buffer, uint32_t sector, uint32_t count)
{
	/* Only allow access to single unit */
	if(unit != 0) {
		return 1;
	}

	/* According to README.txt, count is always 1 - check this! */
	if(count != 1) {
		return 2;
	}

	/* Invalidate cache */
	last_sector = 0xffffffff;

	/* Forward to PIOS */
	int32_t status;
	if((status = PIOS_SDCARD_SectorWrite(sector, buffer)) < 0) {
		/* Cannot access SD Card */
		return 3;
	}

	/* Success */
	return 0;
}