tff.c

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/*--------------------------------------------------------------------------/
/  Tiny FatFs - FAT file system module R0.02a                (C)ChaN, 2006
/---------------------------------------------------------------------------/
/ FatFs module is an experimenal project to implement FAT file system to
/ cheap microcontrollers. This is opened for education, reserch and
/ development. You can use, modify and republish it for non-profit or profit
/ use without any limitation under your responsibility.
/---------------------------------------------------------------------------/
/  Feb 26, 2006  R0.00  Prototype
/  Apr 29, 2006  R0.01  First stable version
/  Jun 01, 2006  R0.02  Added FAT12. Removed unbuffered mode.
/                       Fixed a problem on small (<32M) patition.
/  Jun 10, 2006  R0.02a Added a configuration option (_FS_MINIMUM).
/---------------------------------------------------------------------------*/


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


FATFS *FatFs;			/* Pointer to the file system object */


/*-------------------------------------------------------------------------
  Module Private Functions
-------------------------------------------------------------------------*/

/*----------------------*/
/* Change Window Offset */

static
BOOL move_window (
	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 */
#ifndef _FS_READONLY
		BYTE n;
		if (fs->winflag) {	/* Write back dirty window if needed */
			if (disk_write(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;
					if (disk_write(fs->win, wsect, 1) != RES_OK) break;
				}
			}
		}
#endif
		if (sector) {
			if (disk_read(fs->win, sector, 1) != RES_OK) return FALSE;
			fs->winsect = sector;
		}
	}
	return TRUE;
}



/*----------------------*/
/* Get a Cluster Status */

static
WORD get_cluster (WORD 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;
		if (fs->fs_type == FS_FAT12) {
			bc = clust * 3 / 2;
			if (!move_window(fatsect + bc / 512)) return 1;
			wc = fs->win[bc % 512]; bc++;
			if (!move_window(fatsect + bc / 512)) return 1;
			wc |= (WORD)fs->win[bc % 512] << 8;
			return (clust & 1) ? (wc >> 4) : (wc & 0xFFF);
		} else {
			if (!move_window(fatsect + clust / 256)) return 1;
			return LD_WORD(&(fs->win[(clust * 2) % 512]));
		}
	}
	return 1;	/* Return with 1 means function failed */
}



/*-------------------------*/
/* Change a Cluster Status */

#ifndef _FS_READONLY
static
BOOL put_cluster (
	WORD clust,		/* Cluster# to change */
	WORD val		/* New value to mark the cluster */
)
{
	WORD bc;
	BYTE *p;
	DWORD fatsect;
	FATFS *fs = FatFs;


	fatsect = fs->fatbase;
	if (fs->fs_type == FS_FAT12) {
		bc = 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;
		fs->winflag = 1; bc++;
		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));
	} else {
		if (!move_window(fatsect + clust / 256)) return FALSE;
		ST_WORD(&(fs->win[((WORD)clust * 2) % 512]), (WORD)val);
	}

	fs->winflag = 1;
	return TRUE;
}
#endif /* _FS_READONLY */



/*------------------------*/
/* Remove a Cluster Chain */

#ifndef _FS_READONLY
static
BOOL remove_chain (
	WORD clust			/* Cluster# to remove chain from */
)
{
	WORD nxt;


	while ((nxt = get_cluster(clust)) >= 2) {
		if (!put_cluster(clust, 0)) return FALSE;
		clust = nxt;
	}
	return TRUE;
}
#endif



/*-----------------------------------*/
/* Stretch or Create a Cluster Chain */

#ifndef _FS_READONLY
static
DWORD create_chain (
	WORD clust		 /* Cluster# to stretch, 0 means create new */
)
{
	WORD ncl, ccl, mcl = FatFs->max_clust;


	if (clust == 0) {	/* Create new chain */
		ncl = 1;
		do {
			ncl++;						/* Check next cluster */
			if (ncl >= mcl) return 0;	/* No free custer was found */
			ccl = get_cluster(ncl);		/* Get the cluster status */
			if (ccl == 1) return 0;		/* Any error occured */
		} while (ccl);				/* Repeat until find a free cluster */
	}
	else {				/* Stretch existing chain */
		ncl = get_cluster(clust);	/* Check the cluster status */
		if (ncl < 2) return 0;		/* It is an invalid cluster */
		if (ncl < mcl) return ncl;	/* It is already followed by next cluster */
		ncl = clust;				/* Search free cluster */
		do {
			ncl++;						/* Check next cluster */
			if (ncl >= mcl) ncl = 2;	/* Wrap around */
			if (ncl == clust) return 0;	/* No free custer was found */
			ccl = get_cluster(ncl);		/* Get the cluster status */
			if (ccl == 1) return 0;		/* Any error occured */
		} while (ccl);				/* Repeat until find a free cluster */
	}

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

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



/*----------------------------*/
/* Get Sector# from Cluster#  */

static
DWORD clust2sect (
	WORD clust		/* Cluster# to be converted */
)
{
	FATFS *fs = FatFs;


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



/*------------------------*/
/* Check File System Type */

static
BYTE check_fs (
	DWORD sect			/* Sector# to check if it is a FAT boot record or not */
)
{
	static const char fatsign[] = "FAT12FAT16";
	FATFS *fs = FatFs;


	memset(fs->win, 0, 512);
	if (disk_read(fs->win, sect, 1) == RES_OK) {	/* Load boot record */
		if (LD_WORD(&(fs->win[510])) == 0xAA55) {		/* Is it valid? */
			if (!memcmp(&(fs->win[0x36]), &fatsign[0], 5))
				return FS_FAT12;
			if (!memcmp(&(fs->win[0x36]), &fatsign[5], 5))
				return FS_FAT16;
		}
	}
	return 0;
}



/*--------------------------------*/
/* Move Directory Pointer to Next */

static
BOOL next_dir_entry (
	DIR *scan			/* Pointer to directory object */
)
{
	WORD clust;
	WORD idx;
	FATFS *fs = FatFs;


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



/*--------------------------------------*/
/* Get File Status from Directory Entry */

#ifndef _FS_MINIMUM
static
void get_fileinfo (
	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 = *(dir+12);	/* 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;
	}
	if (*(dir+8) != ' ') {		/* Convert file name (extension) */
		*p++ = '.';
		for (n = 8; n < 11; n++) {
			c = *(dir+n);
			if (c == ' ') break;
			if ((a & 0x10) && (c >= 'A') && (c <= 'Z')) c += 0x20;
			*p++ = c;
		}
	}
	*p = '\0';

	finfo->fattrib = *(dir+11);			/* Attribute */
	finfo->fsize = LD_DWORD(dir+28);	/* Size */
	finfo->fdate = LD_WORD(dir+24);		/* Date */
	finfo->ftime = LD_WORD(dir+22);		/* Time */
}
#endif /* _FS_READONLY */


/*-----------------------------------------------------*/
/* Pick a Paragraph and Create Name in Directory Entry */

static
char make_dirfile (
	const char **path,		/* Pointer to the file path pointer */
	char *dirname			/* Pointer to directory name buffer {Name(8), Ext(3), NT flag(1)} */
)
{
	BYTE n, t, c, a, b;


	memset(dirname, ' ', 8+3);	/* Fill buffer with spaces */
	a = 0; b = 0x18;	/* NT flag */
	n = 0; t = 8;
	for (;;) {
		c = *(*path)++;
		if (c <= ' ') c = 0;
		if ((c == 0) || (c == '/')) {			/* Reached to end of str or directory separator */
			if (n == 0) break;
			dirname[11] = a & b; return c;
		}
		if (c == '.') {
			if(!(a & 1) && (n >= 1) && (n <= 8)) {	/* Enter extension part */
				n = 8; t = 11; continue;
			}
			break;
		}
#ifdef _USE_SJIS
		if (((c >= 0x81) && (c <= 0x9F)) ||		/* Accept S-JIS code */
		    ((c >= 0xE0) && (c <= 0xFC))) {
			if ((n == 0) && (c == 0xE5))		/* Change heading \xE5 to \x05 */
				c = 0x05;
			a ^= 1; goto md_l2;
		}
		if ((c >= 0x7F) && (c <= 0x80)) break;	/* Reject \x7F \x80 */
#else
		if (c >= 0x7F) goto md_l1;				/* Accept \x7F-0xFF */
#endif
		if (c == '"') break;					/* Reject " */
		if (c <= ')') goto md_l1;				/* Accept ! # $ % & ' ( ) */
		if (c <= ',') break;					/* Reject * + , */
		if (c <= '9') goto md_l1;				/* Accept - 0-9 */
		if (c <= '?') break;					/* Reject : ; < = > ? */
		if (!(a & 1)) {	/* These checks are not applied to S-JIS 2nd byte */
			if (c == '|') break;				/* Reject | */
			if ((c >= '[') && (c <= ']')) break;/* Reject [ \ ] */
			if ((c >= 'A') && (c <= 'Z'))
				(t == 8) ? (b &= ~0x08) : (b &= ~0x10);
			if ((c >= 'a') && (c <= 'z')) {		/* Convert to upper case */
				c -= 0x20;
				(t == 8) ? (a |= 0x08) : (a |= 0x10);
			}
		}
	md_l1:
		a &= ~1;
	md_l2:
		if (n >= t) break;
		dirname[n++] = c;
	}
	return 1;
}



/*-------------------*/
/* Trace a File Path */

static
FRESULT trace_path (
	DIR *scan,			/* Pointer to directory object to return last directory */
	char *fn,			/* Pointer to last segment name to return */
	const char *path,	/* Full-path string to trace a file or directory */
	BYTE **dir			/* Directory pointer in Win[] to retutn */
)
{