FAT fragmentation is not handled at all

[parasyte]

When the file system on SD gets fragmented (by adding and removing small files) alt64 will be unable to read some files correctly, especially when loading ROMs. See:

alt64/menu.c

Lines 1315 to 1322 in 3ba0910

	if(mb<=32){
	resp = diskRead(begin_sector, (void *)0xb0000000, file_sectors); //2048 cluster 1Mb
	}
	else{
	resp = diskRead(begin_sector, (void *)0xb0000000, lower_half);
	sleep(10);
	resp = diskRead(begin_sector+lower_half, (void *)0xb2000000, file_sectors-lower_half);
	}

The issue is that the code assumes there is no fragmentation, so it just does a pure DMA from SD, starting with the first sector in the FAT.

A fragmented ROM will be read incorrectly, and usually will not boot. (Or it may boot and crash later, or have other strange errors.)