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Have FAT filesystem respect storage buffer alignment on reads 

This is just a minor cleanup of Solomon Peachy's code, and using
per-filesystem buffers instead of a single static buffer.

Tested and working on the FiiO M3K.

Change-Id: I3c19e8cc24e2f8aa07668c9d1c6d63364815050a
This commit is contained in:
Aidan MacDonald 2021-03-08 11:29:05 +00:00 committed by Solomon Peachy
parent f00eea4434
commit ea1aef9b82
1 changed files with 36 additions and 2 deletions
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38
firmware/drivers/fat.c
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@ -266,6 +266,13 @@ static struct bpb
} fat_bpbs[NUM_VOLUMES]; /* mounted partition info */
#ifdef STORAGE_WANTS_ALIGN
#define FAT_BOUNCE_SECTORS 10
static uint8_t fat_bounce_buffers[NUM_VOLUMES][SECTOR_SIZE*FAT_BOUNCE_SECTORS] STORAGE_ALIGN_ATTR;
#define FAT_BOUNCE_BUFFER(bpb) \
(fat_bounce_buffers[IF_MV_VOL((bpb)->volume)])
#endif
#define IS_FAT_SECTOR(bpb, sector) \
(!((sector) >= (bpb)->fatrgnend || (sector) < (bpb)->fatrgnstart))
@ -2385,8 +2392,35 @@ static long transfer(struct bpb *fat_bpb, unsigned long start, long count,
}
else
{
rc = storage_read_sectors(IF_MD(fat_bpb->drive,)
start + fat_bpb->startsector, count, buf);
void* xferbuf = buf;
#ifdef STORAGE_WANTS_ALIGN
int remain = count;
int xferred = 0;
int aligned = 1;
if(STORAGE_OVERLAP((uintptr_t)buf)) {
xferbuf = FAT_BOUNCE_BUFFER(fat_bpb);
aligned = 0;
count = MIN(remain, FAT_BOUNCE_SECTORS);
}
while(remain > 0) {
#endif
rc = storage_read_sectors(IF_MD(fat_bpb->drive,)
start + fat_bpb->startsector, count, xferbuf);
#ifdef STORAGE_WANTS_ALIGN
if(rc < 0)
break;
if(LIKELY(aligned))
break;
memcpy(buf, xferbuf, count * SECTOR_SIZE);
buf += count * SECTOR_SIZE;
xferred += count;
start += count;
remain -= count;
count = MIN(remain, FAT_BOUNCE_SECTORS);
}
#endif
}
if (rc < 0)