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Optimized initdisk.c by using constants instead of variables where possible.

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git-svn-id: https://svn.code.sf.net/p/freedos/svn/kernel/trunk@1450 6ac86273-5f31-0410-b378-82cca8765d1b
This commit is contained in:
Bart Oldeman 2009-06-17 17:57:36 +00:00
parent a93b71a18b
commit 9e0b5e5bf6
1 changed files with 41 additions and 41 deletions
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82
kernel/initdisk.c
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@ -394,25 +394,24 @@ void printCHS(char *title, struct CHS *chs)
Portions copyright 1992, 1993 Remy Card Portions copyright 1992, 1993 Remy Card
and 1991 Linus Torvalds and 1991 Linus Torvalds
*/ */
/* defaults: */
#define MAXCLUSTSIZE 128
#define NSECTORFAT12 8
#define NFAT 2
VOID CalculateFATData(ddt * pddt, ULONG NumSectors, UBYTE FileSystem) VOID CalculateFATData(ddt * pddt, ULONG NumSectors, UBYTE FileSystem)
{ {
UBYTE maxclustsize;
ULONG fatdata; ULONG fatdata;
bpb *defbpb = &pddt->ddt_defbpb; bpb *defbpb = &pddt->ddt_defbpb;
/* FAT related items */ /* FAT related items */
defbpb->bpb_nfat = 2; defbpb->bpb_nfat = NFAT;
defbpb->bpb_ndirent = (FileSystem == FAT32
|| FileSystem == FAT32_LBA) ? 0 : 512;
/* normal value of number of entries in root dir */ /* normal value of number of entries in root dir */
defbpb->bpb_nreserved = (FileSystem == FAT32 defbpb->bpb_ndirent = 512;
|| FileSystem == FAT32_LBA) ? 0x20 : 1; defbpb->bpb_nreserved = 1;
/* SEC_SIZE * DIRENT_SIZE / defbpb->bpb_ndirent + defbpb->bpb_nreserved */
fatdata = fatdata = NumSectors - (DIRENT_SIZE + 1);
NumSectors - cdiv(defbpb->bpb_ndirent * DIRENT_SIZE,
defbpb->bpb_nbyte) - defbpb->bpb_nreserved;
maxclustsize = 128;
#ifdef DEBUG #ifdef DEBUG
if (FileSystem != FAT12) if (FileSystem != FAT12)
DebugPrintf(("%ld sectors for FAT+data, starting with %d sectors/cluster\n", fatdata, defbpb->bpb_nsector)); DebugPrintf(("%ld sectors for FAT+data, starting with %d sectors/cluster\n", fatdata, defbpb->bpb_nsector));
@ -423,9 +422,9 @@ VOID CalculateFATData(ddt * pddt, ULONG NumSectors, UBYTE FileSystem)
case FAT12: case FAT12:
case FAT12_LBA: case FAT12_LBA:
{ {
unsigned fatdat, fatlength, clust, maxclust; unsigned fatdat;
/* in DOS, FAT12 defaults to 4096kb (8 sector) - clusters. */ /* in DOS, FAT12 defaults to 4096kb (8 sector) - clusters. */
defbpb->bpb_nsector = 8; defbpb->bpb_nsector = NSECTORFAT12;
/* Force maximal fatdata=32696 sectors since with our only possible sector /* Force maximal fatdata=32696 sectors since with our only possible sector
size (512 bytes) this is the maximum for 4k clusters. size (512 bytes) this is the maximum for 4k clusters.
#clus*secperclus+#fats*fatlength= 4077 * 8 + 2 * 12 = 32640. #clus*secperclus+#fats*fatlength= 4077 * 8 + 2 * 12 = 32640.
@ -433,26 +432,28 @@ VOID CalculateFATData(ddt * pddt, ULONG NumSectors, UBYTE FileSystem)
fatdat = (unsigned)fatdata; fatdat = (unsigned)fatdata;
if (fatdata > 32640) if (fatdata > 32640)
fatdat = 32640; fatdat = 32640;
/* The "+2*defbpb->bpb_nsector" is for the reserved first two FAT entries */ /* The "+2*NSECTOR" is for the reserved first two FAT entries */
fatlength = cdiv(fatdat + 2 * defbpb->bpb_nsector, defbpb->bpb_nfsect = cdiv(fatdat + 2 * NSECTORFAT12,
defbpb->bpb_nbyte * 2 * defbpb->bpb_nsector / 3 + SEC_SIZE * 2 * NSECTORFAT12 / 3 + NFAT);
defbpb->bpb_nfat); #if DEBUG
/* Need to calculate number of clusters, since the unused parts of the /* Need to calculate number of clusters, since the unused parts of the
* FATS and data area together could make up space for an additional, * FATS and data area together could make up space for an additional,
* not really present cluster. */ * not really present cluster.
clust = * (This is really done in fatfs.c, bpbtodpb) */
(fatdat - defbpb->bpb_nfat * fatlength) / defbpb->bpb_nsector;
maxclust = (fatlength * 2 * defbpb->bpb_nbyte) / 3;
if (maxclust > FAT12MAX)
maxclust = FAT12MAX;
DebugPrintf(("FAT12: #clu=%u, fatlength=%u, maxclu=%u, limit=%u\n",
clust, fatlength, maxclust, FAT12MAX));
if (clust > maxclust - 2)
{ {
clust = maxclust - 2; unsigned clust = (fatdat - 2 * defbpb->bpb_nfsect) / NSECTORFAT12;
DebugPrintf(("FAT12: too many clusters: setting to maxclu-2\n")); unsigned maxclust = (defbpb->bpb_nfsect * 2 * SEC_SIZE) / 3;
if (maxclust > FAT12MAX)
maxclust = FAT12MAX;
printf(("FAT12: #clu=%u, fatlength=%u, maxclu=%u, limit=%u\n",
clust, defbpb->bpb_nfsect, maxclust, FAT12MAX));
if (clust > maxclust - 2)
{
clust = maxclust - 2;
printf(("FAT12: too many clusters: setting to maxclu-2\n"));
}
} }
defbpb->bpb_nfsect = fatlength; #endif
memcpy(pddt->ddt_fstype, MSDOS_FAT12_SIGN, 8); memcpy(pddt->ddt_fstype, MSDOS_FAT12_SIGN, 8);
break; break;
} }
@ -477,14 +478,12 @@ VOID CalculateFATData(ddt * pddt, ULONG NumSectors, UBYTE FileSystem)
defbpb->bpb_nsector)); defbpb->bpb_nsector));
fatlength = (unsigned)cdiv(fatdata + 2 * defbpb->bpb_nsector, fatlength = (unsigned)cdiv(fatdata + 2 * defbpb->bpb_nsector,
(ULONG)defbpb->bpb_nbyte * defbpb->bpb_nsector / 2 + (SEC_SIZE/2) * defbpb->bpb_nsector + NFAT);
defbpb->bpb_nfat);
/* Need to calculate number of clusters, since the unused parts of the /* Need to calculate number of clusters, since the unused parts of the
* FATS and data area together could make up space for an additional, * FATS and data area together could make up space for an additional,
* not really present cluster. */ * not really present cluster. */
clust = clust = (fatdata - NFAT * fatlength) / defbpb->bpb_nsector;
(fatdata - defbpb->bpb_nfat * fatlength) / defbpb->bpb_nsector; maxclust = (unsigned long)fatlength * (SEC_SIZE/2);
maxclust = ((unsigned long)fatlength * defbpb->bpb_nbyte) / 2;
if (maxclust > FAT16MAX) if (maxclust > FAT16MAX)
maxclust = FAT16MAX; maxclust = FAT16MAX;
DebugPrintf(("FAT16: #clu=%lu, fatlen=%u, maxclu=%lu, limit=%u\n", DebugPrintf(("FAT16: #clu=%lu, fatlen=%u, maxclu=%lu, limit=%u\n",
@ -505,7 +504,7 @@ VOID CalculateFATData(ddt * pddt, ULONG NumSectors, UBYTE FileSystem)
break; break;
defbpb->bpb_nsector <<= 1; defbpb->bpb_nsector <<= 1;
} }
while (defbpb->bpb_nsector && defbpb->bpb_nsector <= maxclustsize); while (defbpb->bpb_nsector && defbpb->bpb_nsector <= MAXCLUSTSIZE);
defbpb->bpb_nfsect = fatlength; defbpb->bpb_nfsect = fatlength;
memcpy(pddt->ddt_fstype, MSDOS_FAT16_SIGN, 8); memcpy(pddt->ddt_fstype, MSDOS_FAT16_SIGN, 8);
break; break;
@ -530,17 +529,18 @@ VOID CalculateFATData(ddt * pddt, ULONG NumSectors, UBYTE FileSystem)
if (NumSectors <= 532480UL) /* disks up to 260 MB, 0.5K cluster */ if (NumSectors <= 532480UL) /* disks up to 260 MB, 0.5K cluster */
nsector = 1; nsector = 1;
defbpb->bpb_nsector = nsector; defbpb->bpb_nsector = nsector;
defbpb->bpb_ndirent = 0;
defbpb->bpb_nreserved = 0x20;
fatdata = NumSectors - 0x20;
do do
{ {
fatlength = cdiv(fatdata + 2 * defbpb->bpb_nsector, fatlength = cdiv(fatdata + 2 * defbpb->bpb_nsector,
(ULONG)defbpb->bpb_nbyte * defbpb->bpb_nsector / 4 + (SEC_SIZE/4) * defbpb->bpb_nsector + NFAT);
defbpb->bpb_nfat);
/* Need to calculate number of clusters, since the unused parts of the /* Need to calculate number of clusters, since the unused parts of the
* FATS and data area together could make up space for an additional, * FATS and data area together could make up space for an additional,
* not really present cluster. */ * not really present cluster. */
clust = clust = (fatdata - NFAT * fatlength) / defbpb->bpb_nsector;
(fatdata - defbpb->bpb_nfat * fatlength) / defbpb->bpb_nsector; maxclust = fatlength * (SEC_SIZE/4);
maxclust = (fatlength * defbpb->bpb_nbyte) / 4;
if (maxclust > FAT32MAX) if (maxclust > FAT32MAX)
maxclust = FAT32MAX; maxclust = FAT32MAX;
DebugPrintf(("FAT32: #clu=%u, fatlen=%u, maxclu=%u, limit=%u\n", DebugPrintf(("FAT32: #clu=%u, fatlen=%u, maxclu=%u, limit=%u\n",
@ -554,7 +554,7 @@ VOID CalculateFATData(ddt * pddt, ULONG NumSectors, UBYTE FileSystem)
break; break;
defbpb->bpb_nsector <<= 1; defbpb->bpb_nsector <<= 1;
} }
while (defbpb->bpb_nsector && defbpb->bpb_nsector <= maxclustsize); while (defbpb->bpb_nsector && defbpb->bpb_nsector <= MAXCLUSTSIZE);
defbpb->bpb_nfsect = 0; defbpb->bpb_nfsect = 0;
defbpb->bpb_xnfsect = fatlength; defbpb->bpb_xnfsect = fatlength;
/* set up additional FAT32 fields */ /* set up additional FAT32 fields */