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Using a FAT32 table so that FATs won't be too big for drives <= 64 GB 

git-svn-id: https://svn.code.sf.net/p/freedos/svn/kernel/trunk@754 6ac86273-5f31-0410-b378-82cca8765d1b
This commit is contained in:
Bart Oldeman 2004-01-26 02:01:34 +00:00
parent 4f1a117069
commit 3d7d36cf91
1 changed files with 14 additions and 4 deletions
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18
kernel/initdisk.c
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@ -501,10 +501,20 @@ VOID CalculateFATData(ddt FAR * pddt, ULONG NumSectors, UBYTE FileSystem)
{
unsigned long fatlength, clust, maxclust;
/* For FAT32, use 4k clusters on sufficiently large file systems,
* otherwise 1 sector per cluster. This is also what M$'s format
* command does for FAT32. */
defbpb->bpb_nsector = (NumSectors >= 512 * 1024ul ? 8 : 1);
/* For FAT32, use the cluster size table described in the FAT spec:
* http://www.microsoft.com/hwdev/download/hardware/fatgen103.pdf
*/
unsigned sz_gb = (unsigned)(NumSectors / 2097152UL);
unsigned char nsector = 64; /* disks greater than 32 GB, 32K cluster */
if (sz_gb <= 32) /* disks up to 32 GB, 16K cluster */
nsector = 32;
if (sz_gb <= 16) /* disks up to 16 GB, 8K cluster */
nsector = 16;
if (sz_gb <= 8) /* disks up to 8 GB, 4K cluster */
nsector = 8;
if (NumSectors <= 532480) /* disks up to 260 MB, 0.5K cluster */
nsector = 1;
defbpb->bpb_nsector = nsector;
do
{
fatlength = cdiv(fatdata + 2 * defbpb->bpb_nsector,