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Add support for some edge case FATFS variants. #20

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Add support for some edge case FATFS variants. #20

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e1f90c1
Allow sector sizes down to 256 bytes.
davidgiven Jan 10, 2026
a2f912b
Add an option for case-insensitive SFN comparisons.
davidgiven Jan 10, 2026
302e6d6
Merge branch 'master' into R0.14b-fluxengine
davidgiven Jan 10, 2026
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28 changes: 25 additions & 3 deletions source/ff.c
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Original file line number Diff line number Diff line change
Expand Up @@ -256,7 +256,7 @@


/* Definitions of sector size */
#if (FF_MAX_SS < FF_MIN_SS) || (FF_MAX_SS != 512 && FF_MAX_SS != 1024 && FF_MAX_SS != 2048 && FF_MAX_SS != 4096) || (FF_MIN_SS != 512 && FF_MIN_SS != 1024 && FF_MIN_SS != 2048 && FF_MIN_SS != 4096)
#if (FF_MAX_SS < FF_MIN_SS) || (FF_MAX_SS != 256 && FF_MAX_SS != 512 && FF_MAX_SS != 1024 && FF_MAX_SS != 2048 && FF_MAX_SS != 4096) || (FF_MIN_SS != 256 && FF_MIN_SS != 512 && FF_MIN_SS != 1024 && FF_MIN_SS != 2048 && FF_MIN_SS != 4096)
#error Wrong sector size configuration
#endif
#if FF_MAX_SS == FF_MIN_SS
Expand Down Expand Up @@ -2409,6 +2409,28 @@ static FRESULT dir_read (
/* Directory handling - Find an object in the directory */
/*-----------------------------------------------------------------------*/

static int compare_filenames(const char* s1, const char* s2, size_t n)
{
#if FF_CASE_INSENSITIVE_COMPARISONS
while (n--)
{
char c1 = *s1++;
char c2 = *s2++;
int d;

if (IsLower(c1)) c1 -= 0x20; /* To upper ASCII char */
if (IsLower(c2)) c2 -= 0x20; /* To upper ASCII char */

d = c1 - c2;
if (d)
return d;
}
return 0;
#else
return memcmp(s1, s2, n);
#endif
}

static FRESULT dir_find ( /* FR_OK(0):succeeded, !=0:error */
DIR* dp /* Pointer to the directory object with the file name */
)
Expand Down Expand Up @@ -2469,13 +2491,13 @@ static FRESULT dir_find ( /* FR_OK(0):succeeded, !=0:error */
}
} else { /* SFN entry */
if (ord == 0 && sum == sum_sfn(dp->dir)) break; /* LFN matched? */
if (!(dp->fn[NSFLAG] & NS_LOSS) && !memcmp(dp->dir, dp->fn, 11)) break; /* SFN matched? */
if (!(dp->fn[NSFLAG] & NS_LOSS) && !compare_filenames(dp->dir, dp->fn, 11)) break; /* SFN matched? */
ord = 0xFF; dp->blk_ofs = 0xFFFFFFFF; /* Not matched, reset LFN sequence */
}
}
#else /* Non LFN configuration */
dp->obj.attr = dp->dir[DIR_Attr] & AM_MASK;
if (!(dp->dir[DIR_Attr] & AM_VOL) && !memcmp(dp->dir, dp->fn, 11)) break; /* Is it a valid entry? */
if (!(dp->dir[DIR_Attr] & AM_VOL) && !compare_filenames(dp->dir, dp->fn, 11)) break; /* Is it a valid entry? */
#endif
res = dir_next(dp, 0); /* Next entry */
} while (res == FR_OK);
Expand Down
5 changes: 5 additions & 0 deletions source/ffconf.h
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Expand Up @@ -161,6 +161,11 @@
/ 2: f_getcwd() is available in addition to 1.
*/

#define FF_CASE_INSENSITIVE_COMPARISONS 0
/* This option enables case insensitive comparisons for SFNs, needed by some
/ FATFS variants which store lowercase filenames instead of the usual uppercase
/ ones.
*/

#define FF_PATH_DEPTH 10
/* This option defines maximum depth of directory in the exFAT volume. It is NOT
Expand Down