/*--------------------------------------------------------------------------/
/  FatFs - Tiny FAT file system module  R0.05                 (C)ChaN, 2007
/---------------------------------------------------------------------------/
/ The FatFs module is an experimenal project to implement FAT file system to
/ cheap microcontrollers. This is a free software and is opened for education,
/ research and development under license policy of following trems.
/
/  Copyright (C) 2007, ChaN, all right reserved.
/
/ * The FatFs module is a free software and there is no warranty.
/ * You can use, modify and/or redistribute it for personal, non-profit or
/   profit use without any restriction under your responsibility.
/ * Redistributions of source code must retain the above copyright notice.
/
/---------------------------------------------------------------------------/
/  Feb 26, 2006  R0.00  Prototype.
/  Apr 29, 2006  R0.01  First stable version.
/  Jun 01, 2006  R0.02  Added FAT12 support.
/                       Removed unbuffered mode.
/                       Fixed a problem on small (<32M) patition.
/  Jun 10, 2006  R0.02a Added a configuration option (_FS_MINIMUM).
/  Sep 22, 2006  R0.03  Added f_rename().
/                       Changed option _FS_MINIMUM to _FS_MINIMIZE.
/  Dec 09, 2006  R0.03a Improved cluster scan algolithm to write files fast.
/  Feb 04, 2007  R0.04  Added FAT32 supprt.
/                       Changed some interfaces incidental to FatFs.
/                       Changed f_mountdrv() to f_mount().
/  Apr 01, 2007  R0.04a Added a capability of extending file size to f_lseek().
/                       Added minimization level 3.
/                       Fixed a problem in FAT32 support.
/  May 05, 2007  R0.04b Added a configuration option _USE_NTFLAG.
/                       Added FSInfo support.
/                       Fixed some problems corresponds to FAT32 support.
/                       Fixed DBCS name can result FR_INVALID_NAME.
/                       Fixed short seek (<= csize) collapses the file object.
/  Aug 25, 2007  R0.05  Changed arguments of f_read() and f_write().
/---------------------------------------------------------------------------*/

#include <string.h>
#include "tff.h"		/* Tiny-FatFs declarations */
#include "diskio.h"		/* Include file for user provided disk functions */


static
FATFS *FatFs;			/* Pointer to the file system objects (logical drive) */
static
WORD fsid;				/* File system mount ID */


/*-------------------------------------------------------------------------

  Module Private Functions

-------------------------------------------------------------------------*/


/*-----------------------------------------------------------------------*/
/* Change window offset                                                  */
/*-----------------------------------------------------------------------*/

static
BOOL move_window (		/* TRUE: successful, FALSE: failed */
	DWORD sector		/* Sector number to make apperance in the FatFs->win */
)						/* Move to zero only writes back dirty window */
{
	DWORD wsect;
	FATFS *fs = FatFs;


	wsect = fs->winsect;
	if (wsect != sector) {	/* Changed current window */
#if !_FS_READONLY
		BYTE n;
		if (fs->winflag) {	/* Write back dirty window if needed */
			if (disk_write(0, fs->win, wsect, 1) != RES_OK)
				return FALSE;
			fs->winflag = 0;
			if (wsect < (fs->fatbase + fs->sects_fat)) {	/* In FAT area */
				for (n = fs->n_fats; n >= 2; n--) {	/* Refrect the change to all FAT copies */
					wsect += fs->sects_fat;
					disk_write(0, fs->win, wsect, 1);
				}
			}
		}
#endif
		if (sector) {
			if (disk_read(0, fs->win, sector, 1) != RES_OK)
				return FALSE;
			fs->winsect = sector;
		}
	}
	return TRUE;
}




/*-----------------------------------------------------------------------*/
/* Clean-up cached data                                                  */
/*-----------------------------------------------------------------------*/

#if !_FS_READONLY
static
FRESULT sync (void)		/* FR_OK: successful, FR_RW_ERROR: failed */
{
	FATFS *fs = FatFs;


	fs->winflag = 1;
	if (!move_window(0)) return FR_RW_ERROR;
#if _USE_FSINFO
	/* Update FSInfo sector if needed */
	if (fs->fs_type == FS_FAT32 && fs->fsi_flag) {
		fs->winsect = 0;
		memset(fs->win, 0, 512);
		ST_WORD(&fs->win[BS_55AA], 0xAA55);
		ST_DWORD(&fs->win[FSI_LeadSig], 0x41615252);
		ST_DWORD(&fs->win[FSI_StrucSig], 0x61417272);
		ST_DWORD(&fs->win[FSI_Free_Count], fs->free_clust);
		ST_DWORD(&fs->win[FSI_Nxt_Free], fs->last_clust);
		disk_write(0, fs->win, fs->fsi_sector, 1);
		fs->fsi_flag = 0;
	}
#endif
	/* Make sure that no pending write process in the physical drive */
	if (disk_ioctl(0, CTRL_SYNC, NULL) != RES_OK) return FR_RW_ERROR;
	return FR_OK;
}
#endif




/*-----------------------------------------------------------------------*/
/* Get a cluster status                                                  */
/*-----------------------------------------------------------------------*/

static
CLUST get_cluster (		/* 0,>=2: successful, 1: failed */
	CLUST clust			/* Cluster# to get the link information */
)
{
	WORD wc, bc;
	DWORD fatsect;
	FATFS *fs = FatFs;


	if (clust >= 2 && clust < fs->max_clust) {		/* Valid cluster# */
		fatsect = fs->fatbase;
		switch (fs->fs_type) {
		case FS_FAT12 :
			bc = (WORD)clust * 3 / 2;
			if (!move_window(fatsect + bc / 512)) break;
			wc = fs->win[bc % 512]; bc++;
			if (!move_window(fatsect + bc / 512)) break;
			wc |= (WORD)fs->win[bc % 512] << 8;
			return (clust & 1) ? (wc >> 4) : (wc & 0xFFF);

		case FS_FAT16 :
			if (!move_window(fatsect + clust / 256)) break;
			return LD_WORD(&fs->win[((WORD)clust * 2) % 512]);
#if _FAT32
		case FS_FAT32 :
			if (!move_window(fatsect + clust / 128)) break;
			return LD_DWORD(&fs->win[((WORD)clust * 4) % 512]) & 0x0FFFFFFF;
#endif
		}
	}

	return 1;	/* There is no cluster information, or an error occured */
}




/*-----------------------------------------------------------------------*/
/* Change a cluster status                                               */
/*-----------------------------------------------------------------------*/

#if !_FS_READONLY
static
BOOL put_cluster (		/* TRUE: successful, FALSE: failed */
	CLUST clust,		/* Cluster# to change */
	CLUST val			/* New value to mark the cluster */
)
{
	WORD bc;
	BYTE *p;
	DWORD fatsect;
	FATFS *fs = FatFs;


	fatsect = fs->fatbase;
	switch (fs->fs_type) {
	case FS_FAT12 :
		bc = (WORD)clust * 3 / 2;
		if (!move_window(fatsect + bc / 512)) return FALSE;
		p = &fs->win[bc % 512];
		*p = (clust & 1) ? ((*p & 0x0F) | ((BYTE)val << 4)) : (BYTE)val;
		bc++;
		fs->winflag = 1; 
		if (!move_window(fatsect + bc / 512)) return FALSE;
		p = &fs->win[bc % 512];
		*p = (clust & 1) ? (BYTE)(val >> 4) : ((*p & 0xF0) | ((BYTE)(val >> 8) & 0x0F));
		break;

	case FS_FAT16 :
		if (!move_window(fatsect + clust / 256)) return FALSE;
		ST_WORD(&fs->win[((WORD)clust * 2) % 512], (WORD)val);
		break;
#if _FAT32
	case FS_FAT32 :
		if (!move_window(fatsect + clust / 128)) return FALSE;
		ST_DWORD(&fs->win[((WORD)clust * 4) % 512], val);
		break;
#endif
	default :
		return FALSE;
	}
	fs->winflag = 1;
	return TRUE;
}
#endif /* !_FS_READONLY */




/*-----------------------------------------------------------------------*/
/* Remove a cluster chain                                                */
/*-----------------------------------------------------------------------*/

#if !_FS_READONLY
static
BOOL remove_chain (		/* TRUE: successful, FALSE: failed */
	CLUST clust			/* Cluster# to remove chain from */
)
{
	CLUST nxt;
	FATFS *fs = FatFs;


	while (clust >= 2 && clust < fs->max_clust) {
		nxt = get_cluster(clust);
		if (nxt == 1) return FALSE;
		if (!put_cluster(clust, 0)) return FALSE;
		if (fs->free_clust != (CLUST)0xFFFFFFFF) {
			fs->free_clust++;
#if _USE_FSINFO
			fs->fsi_flag = 1;
#endif
		}
		clust = nxt;
	}
	return TRUE;
}
#endif




/*-----------------------------------------------------------------------*/
/* Stretch or create a cluster chain                                     */
/*-----------------------------------------------------------------------*/

#if !_FS_READONLY
static
CLUST create_chain (	/* 0: no free cluster, 1: error, >=2: new cluster number */
	CLUST clust			/* Cluster# to stretch, 0 means create new */
)
{
	CLUST cstat, ncl, scl, mcl;
	FATFS *fs = FatFs;


	mcl = fs->max_clust;
	if (clust == 0) {		/* Create new chain */
		scl = fs->last_clust;			/* Get last allocated cluster */
		if (scl < 2 || scl >= mcl) scl = 1;
	}
	else {					/* Stretch existing chain */
		cstat = get_cluster(clust);		/* Check the cluster status */
		if (cstat < 2) return 1;		/* It is an invalid cluster */
		if (cstat < mcl) return cstat;	/* It is already followed by next cluster */
		scl = clust;
	}

	ncl = scl;				/* Start cluster */
	for (;;) {
		ncl++;							/* Next cluster */
		if (ncl >= mcl) {				/* Wrap around */
			ncl = 2;
			if (ncl > scl) return 0;	/* No free custer */
		}
		cstat = get_cluster(ncl);		/* Get the cluster status */
		if (cstat == 0) break;			/* Found a free cluster */
		if (cstat == 1) return 1;		/* Any error occured */
		if (ncl == scl) return 0;		/* No free custer */
	}

	if (!put_cluster(ncl, (CLUST)0x0FFFFFFF)) return 1;	/* Mark the new cluster "in use" */
	if (clust && !put_cluster(clust, ncl)) return 1;	/* Link it to previous one if needed */

	fs->last_clust = ncl;				/* Update fsinfo */
	if (fs->free_clust != (CLUST)0xFFFFFFFF) {
		fs->free_clust--;
#if _USE_FSINFO
		fs->fsi_flag = 1;
#endif
	}

	return ncl;		/* Return new cluster number */
}
#endif /* !_FS_READONLY */




/*-----------------------------------------------------------------------*/
/* Get sector# from cluster#                                             */
/*-----------------------------------------------------------------------*/

static
DWORD clust2sect (	/* !=0: sector number, 0: failed - invalid cluster# */
	CLUST clust		/* Cluster# to be converted */
)
{
	FATFS *fs = FatFs;


	clust -= 2;
	if (clust >= (fs->max_clust - 2)) return 0;		/* Invalid cluster# */
	return (DWORD)clust * fs->sects_clust + fs->database;
}




/*-----------------------------------------------------------------------*/
/* Move directory pointer to next                                        */
/*-----------------------------------------------------------------------*/

static
BOOL next_dir_entry (	/* TRUE: successful, FALSE: could not move next */
	DIR *dirobj			/* Pointer to directory object */
)
{
	CLUST clust;
	WORD idx;
	FATFS *fs = FatFs;


	idx = dirobj->index + 1;
	if ((idx & 15) == 0) {		/* Table sector changed? */
		dirobj->sect++;			/* Next sector */
		if (!dirobj->clust) {		/* In static table */
			if (idx >= fs->n_rootdir) return FALSE;	/* Reached to end of table */
		} else {					/* In dynamic table */
			if (((idx / 16) & (fs->sects_clust - 1)) == 0) {	/* Cluster changed? */
				clust = get_cluster(dirobj->clust);			/* Get next cluster */
				if (clust < 2 || clust >= fs->max_clust)	/* Reached to end of table */
					return FALSE;
				dirobj->clust = clust;				/* Initialize for new cluster */
				dirobj->sect = clust2sect(clust);
			}
		}
	}
	dirobj->index = idx;	/* Lower 4 bit of dirobj->index indicates offset in dirobj->sect */
	return TRUE;
}




/*-----------------------------------------------------------------------*/
/* Get file status from directory entry                                  */
/*-----------------------------------------------------------------------*/

#if _FS_MINIMIZE <= 1
static
void get_fileinfo (		/* No return code */
	FILINFO *finfo, 	/* Ptr to store the File Information */
	const BYTE *dir		/* Ptr to the directory entry */
)
{
	BYTE n, c, a;
	char *p;


	p = &finfo->fname[0];
	a = _USE_NTFLAG ? dir[DIR_NTres] : 0;	/* NT flag */
	for (n = 0; n < 8; n++) {	/* Convert file name (body) */
		c = dir[n];
		if (c == ' ') break;
		if (c == 0x05) c = 0xE5;
		if (a & 0x08 && c >= 'A' && c <= 'Z') c += 0x20;
		*p++ = c;
	}