URL https://opencores.org/ocsvn/openrisc/openrisc/trunk
Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [bootloaders/] [orpmon/] [common/] [dosfs.c] - Blame information for rev 743

Go to most recent revision | Details | Compare with Previous | View Log

/*
        DOSFS Embedded FAT-Compatible Filesystem
        (C) 2005 Lewin A.R.W. Edwards (sysadm@zws.com)
 
        You are permitted to modify and/or use this code in your own projects without
        payment of royalty, regardless of the license(s) you choose for those projects.
 
        You cannot re-copyright or restrict use of the code as released by Lewin Edwards.
*/
 
/*
  @2010, adam.edvardsson@orsoc.se
  Added local copy of the functions,
   div_t, memcmp2,strcpy2,strcmp2. The one from the string library is not comatible
 
*/
 
 
//#include <string.h>
//#include <stdlib.h>
//#include "or32_utils.h"
#include "dosfs.h"
#include "sdc.h"
 
#include "common.h"
#include "support.h"
#include "uart.h"
 
 
 
unsigned long int init_fat(VOLINFO * vis)
{
 
 
 
 
unsigned char sector[SECTOR_SIZE];
 
unsigned long int pstart, psize, i, fisz;
 
unsigned char pactive, ptype;
 
VOLINFO vi;
 
 
 
            //uart_init(DEFAULT_UART);
            printf("FAT INIT START\n");
 
memCardInit();
 
 
 
pstart = DFS_GetPtnStart(0, sector, 0, &pactive, &ptype, &psize);
 
if (pstart == 0xffffffff) {
 
printf("Cannot find first partition\n");
 
return -1;
 
}
 
 
printf
            ("Partition 0 start sector 0x%-08.8lX active %-02.2hX type %-02.2hX size %-08.8lX\n",
             pstart, pactive, ptype, psize);
 
 
if (DFS_GetVolInfo(0, sector, pstart, &vi)) {
 
printf("Error getting volume information\n");
 
return -1;
 
}
 
 
 
 
 
*vis = vi;
 
 
 
 
}
 
 
 
 
unsigned long int DFS_ReadSector(unsigned char unit, unsigned char *buffer,
                                    unsigned long int sector,
                                    unsigned long int count)
{
 
 
unsigned long int block_add = 0;
 
int i;
 
 
 
 
for (i = 0; i < count; i++) {
 
block_add = sector + i;
 
DBGA("\n readSector %u, block_addr %u \n", sector, block_add);
 
setup_bd_transfer(READ_OP, block_add, buffer);
 
if (finnish_bd_transfer() == FALSE)
 
return 0xff;
 
 
}
 
 
return 0;
 
 
}
 
 
 
 
unsigned long int DFS_WriteSector(unsigned char unit, unsigned char *buffer,
                                     unsigned long int sector,
                                     unsigned long int count)
{
 
 
 
unsigned long int block_add = 0;
 
unsigned char scr[SECTOR_SIZE];
 
 
block_add = sector;
 
DBGA("\n writeSector %u, block_addr2 %u \n", sector, block_add);
 
setup_bd_transfer(WRITE_OP, block_add, buffer);
 
 
if (finnish_bd_transfer() == FALSE) {
 
printf("TRANSACTION FAILED, Buffer %x \n", buffer);
 
 
                    //reset_card();  
                    // sd_wait_rsp();
                    // SD_REG(SD_SOFTWARE_RST)=1; 
 
                    //SD_REG(SD_SOFTWARE_RST)=0; 
 
 
DBGA("FREE BD TX/RX: 0x%x \n", SD_REG(BD_STATUS));
 
 
 
DBGA("TRY READ SECTOR \n");
 
setup_bd_transfer(READ_OP, 526571008, scr);
 
finnish_bd_transfer();
 
DBGA("PRINT test wreite to 526571008 \n");
 
setup_bd_transfer(WRITE_OP, 526571008, scr);
 
finnish_bd_transfer();
 
 
setup_bd_transfer(WRITE_OP, block_add, buffer);
 
if (finnish_bd_transfer() == FALSE) {
 
printf("TRANSACTION FAILED AGAIN!, Buffer %x \n",
                                buffer);
 
return 0xff;
 
}
 
 
}
 
 
 
return 0;
 
 
}
 
 
 
/*
        Get starting sector# of specified partition on drive #unit
        NOTE: This code ASSUMES an MBR on the disk.
        scratchsector should point to a SECTOR_SIZE scratch area
        Returns 0xffffffff for any error.
        If pactive is non-NULL, this function also returns the partition active flag.
        If pptype is non-NULL, this function also returns the partition type.
        If psize is non-NULL, this function also returns the partition size.
*/
 
 
unsigned long int DFS_GetPtnStart(unsigned char unit,
                                    unsigned char *scratchsector,
                                    unsigned char pnum, unsigned char *pactive,
                                    unsigned char *pptype,
                                    unsigned long int *psize)
{
 
unsigned long int result;
 
PMBR mbr = (PMBR) scratchsector;
 
 
            // DOS ptable supports maximum 4 partitions
            if (pnum > 3)
 
return DFS_ERRMISC;
 
 
            // Read MBR from target media
            if (DFS_ReadSector(unit, scratchsector, 0, 1)) {
 
return DFS_ERRMISC;
 
}
 
 
result = (unsigned long int)mbr->ptable[pnum].start_0 |
            (((unsigned long int)mbr->ptable[pnum].start_1) << 8) |
            (((unsigned long int)mbr->ptable[pnum].start_2) << 16) |
            (((unsigned long int)mbr->ptable[pnum].start_3) << 24);
 
 
 
            //unsigned char              active;                 // 0x80 if partition active
            //unsigned char         start_h;                // starting head
            //unsigned char         start_cs_l;             // starting cylinder and sector (low byte)
            //unsigned char         start_cs_h;             // starting cylinder and sector (high byte)
 
printf("active 0:%x 1:%x 2:%x 3:%x \n", mbr->ptable[pnum].active,
                    mbr->ptable[pnum].start_h, mbr->ptable[pnum].start_cs_l,
                    mbr->ptable[pnum].start_cs_h);
 
 
printf("start 0:%x 1:%x 2:%x 3:%x \n", mbr->ptable[pnum].start_0,
                 mbr->ptable[pnum].start_1, mbr->ptable[pnum].start_2,
                 mbr->ptable[pnum].start_3);
 
if (pactive)
 
*pactive = mbr->ptable[pnum].active;
 
 
if (pptype)
 
*pptype = mbr->ptable[pnum].type;
 
 
if (psize) {
 
*psize = (unsigned long int)mbr->ptable[pnum].size_0 |
                    (((unsigned long int)mbr->ptable[pnum].size_1) << 8) |
                    (((unsigned long int)mbr->ptable[pnum].size_2) << 16) |
                    (((unsigned long int)mbr->ptable[pnum].size_3) << 24);
 
printf("size 0:%x 1:%x 2:%x 3:%x \n", mbr->ptable[pnum].size_0,
                        mbr->ptable[pnum].size_1, mbr->ptable[pnum].size_2,
                        mbr->ptable[pnum].size_3);
 
}
 
 
return result;
 
}
 
 
 
 
 
ldiv_t ldiv(long int numer, long int denom)
{
 
ldiv_t result;
 
 
result.quot = numer / denom;
 
result.rem = numer % denom;
 
 
            /* The ANSI standard says that |QUOT| <= |NUMER / DENOM|, where
               NUMER / DENOM is to be computed in infinite precision.  In
               other words, we should always truncate the quotient towards
               zero, never -infinity.  Machine division and remainer may
               work either way when one or both of NUMER or DENOM is
               negative.  If only one is negative and QUOT has been
               truncated towards -infinity, REM will have the same sign as
               DENOM and the opposite sign of NUMER; if both are negative
               and QUOT has been truncated towards -infinity, REM will be
               positive (will have the opposite sign of NUMER).  These are
               considered `wrong'.  If both are NUM and DENOM are positive,
               RESULT will always be positive.  This all boils down to: if
               NUMER >= 0, but REM < 0, we got the wrong answer.  In that
               case, to get the right answer, add 1 to QUOT and subtract
               DENOM from REM.  */
 
if (numer >= 0 && result.rem < 0)
 
 {
 
++result.quot;
 
result.rem -= denom;
 
}
 
 
return result;
 
}
 
 
 
div_t div(int numer, int denom)
{
 
div_t result;
 
 
result.quot = numer / denom;
 
result.rem = numer % denom;
 
 
            /* The ANSI standard says that |QUOT| <= |NUMER / DENOM|, where
               NUMER / DENOM is to be computed in infinite precision.  In
               other words, we should always truncate the quotient towards
               zero, never -infinity.  Machine division and remainer may
               work either way when one or both of NUMER or DENOM is
               negative.  If only one is negative and QUOT has been
               truncated towards -infinity, REM will have the same sign as
               DENOM and the opposite sign of NUMER; if both are negative
               and QUOT has been truncated towards -infinity, REM will be
               positive (will have the opposite sign of NUMER).  These are
               considered `wrong'.  If both are NUM and DENOM are positive,
               RESULT will always be positive.  This all boils down to: if
               NUMER >= 0, but REM < 0, we got the wrong answer.  In that
               case, to get the right answer, add 1 to QUOT and subtract
               DENOM from REM.  */
 
if (numer >= 0 && result.rem < 0)
 
 {
 
++result.quot;
 
result.rem -= denom;
 
}
 
 
return result;
 
}
 
 
/*
        Retrieve volume info from BPB and store it in a VOLINFO structure
        You must provide the unit and starting sector of the filesystem, and
        a pointer to a sector buffer for scratch
        Attempts to read BPB and glean information about the FS from that.
        Returns 0 OK, nonzero for any error.
*/
unsigned long int DFS_GetVolInfo(unsigned char unit,
                                 unsigned char *scratchsector,
                                 unsigned long int startsector,
                                 PVOLINFO volinfo)
{
 
PLBR lbr = (PLBR) scratchsector;
 
volinfo->unit = unit;
 
volinfo->startsector = startsector;
 
 
if (DFS_ReadSector(unit, scratchsector, startsector, 1))
 
return DFS_ERRMISC;
 
 
// tag: OEMID, refer dosfs.h
//      strncpy(volinfo->oemid, lbr->oemid, 8);
//      volinfo->oemid[8] = 0;
 
volinfo->secperclus = lbr->bpb.secperclus;
 
volinfo->reservedsecs = (unsigned short)lbr->bpb.reserved_l |
            (((unsigned short)lbr->bpb.reserved_h) << 8);
 
 
volinfo->numsecs = (unsigned short)lbr->bpb.sectors_s_l |
            (((unsigned short)lbr->bpb.sectors_s_h) << 8);
 
 
if (!volinfo->numsecs)
 
volinfo->numsecs = (unsigned long int)lbr->bpb.sectors_l_0 |
                    (((unsigned long int)lbr->bpb.sectors_l_1) << 8) |
                    (((unsigned long int)lbr->bpb.sectors_l_2) << 16) |
                    (((unsigned long int)lbr->bpb.sectors_l_3) << 24);
 
 
            // If secperfat is 0, we must be in a FAT32 volume; get secperfat
            // from the FAT32 EBPB. The volume label and system ID string are also
            // in different locations for FAT12/16 vs FAT32.
            volinfo->secperfat = (unsigned short)lbr->bpb.secperfat_l |
            (((unsigned short)lbr->bpb.secperfat_h) << 8);
 
if (!volinfo->secperfat) {
 
volinfo->secperfat =
                    (unsigned long int)lbr->ebpb.ebpb32.
                    fatsize_0 |
 
(((unsigned long int)lbr->ebpb.ebpb32.
                       fatsize_1) << 8) |
(((unsigned long int)lbr->ebpb.
                                             ebpb32.
                                             fatsize_2) << 16) |
(((unsigned
                                                                     long int)
                                                                    lbr->ebpb.
                                                                    ebpb32.
                                                                    fatsize_3)
                                                                   << 24);
 
 
memcpy(volinfo->label, lbr->ebpb.ebpb32.label, 11);
 
volinfo->label[11] = 0;
 
 
// tag: OEMID, refer dosfs.h
//              memcpy(volinfo->system, lbr->ebpb.ebpb32.system, 8);
//              volinfo->system[8] = 0; 
        }
 
        else {
 
memcpy(volinfo->label, lbr->ebpb.ebpb.label, 11);
 
volinfo->label[11] = 0;
 
 
// tag: OEMID, refer dosfs.h
//              memcpy(volinfo->system, lbr->ebpb.ebpb.system, 8);
//              volinfo->system[8] = 0; 
        }
 
 
            // note: if rootentries is 0, we must be in a FAT32 volume.
            volinfo->rootentries = (unsigned short)lbr->bpb.rootentries_l |
            (((unsigned short)lbr->bpb.rootentries_h) << 8);
 
 
            // after extracting raw info we perform some useful precalculations
            volinfo->fat1 = startsector + volinfo->reservedsecs;
 
 
            // The calculation below is designed to round up the root directory size for FAT12/16
            // and to simply ignore the root directory for FAT32, since it's a normal, expandable
            // file in that situation.
            if (volinfo->rootentries) {
 
volinfo->rootdir = volinfo->fat1 + (volinfo->secperfat * 2);
 
volinfo->dataarea =
                    volinfo->rootdir +
                    (((volinfo->rootentries * 32) +
                      (SECTOR_SIZE - 1)) / SECTOR_SIZE);
 
}
 
        else {
 
volinfo->dataarea = volinfo->fat1 + (volinfo->secperfat * 2);
 
volinfo->rootdir =
                    (unsigned long int)lbr->ebpb.ebpb32.
                    root_0 |
(((unsigned long int)lbr->ebpb.ebpb32.root_1) <<
                               8) |
(((unsigned long int)lbr->ebpb.ebpb32.
                                       root_2) << 16) |
(((unsigned long int)
                                                           lbr->ebpb.ebpb32.
                                                           root_3) << 24);
 
}
 
            // Calculate number of clusters in data area and infer FAT type from this information.
            volinfo->numclusters =
            (volinfo->numsecs - volinfo->dataarea) / volinfo->secperclus;
 
if (volinfo->numclusters < 4085)
 
volinfo->filesystem = FAT12;
 
        else if (volinfo->numclusters < 65525)
 
volinfo->filesystem = FAT16;
 
        else
 
volinfo->filesystem = FAT32;
 
 
return DFS_OK;
 
}
 
 
 
/*
        Fetch FAT entry for specified cluster number
        You must provide a scratch buffer for one sector (SECTOR_SIZE) and a populated VOLINFO
        Returns a FAT32 BAD_CLUSTER value for any error, otherwise the contents of the desired
        FAT entry.
        scratchcache should point to a UINT32. This variable caches the physical sector number
        last read into the scratch buffer for performance enhancement reasons.
*/
unsigned long int DFS_GetFAT(PVOLINFO volinfo, unsigned char *scratch,
                             unsigned long int *scratchcache,
                             unsigned long int cluster)
{
 
unsigned long int offset, sector, result;
 
 
if (volinfo->filesystem == FAT12) {
 
offset = cluster + (cluster / 2);
 
}
 
        else if (volinfo->filesystem == FAT16) {
 
offset = cluster * 2;
 
}
 
        else if (volinfo->filesystem == FAT32) {
 
offset = cluster * 4;
 
}
 
        else
 
return 0x0ffffff7;      // FAT32 bad cluster    
 
            // at this point, offset is the BYTE offset of the desired sector from the start
            // of the FAT. Calculate the physical sector containing this FAT entry.
            sector = ldiv(offset, SECTOR_SIZE).quot + volinfo->fat1;
 
 
            // If this is not the same sector we last read, then read it into RAM
            if (sector != *scratchcache) {
 
if (DFS_ReadSector(volinfo->unit, scratch, sector, 1)) {
 
                            // avoid anyone assuming that this cache value is still valid, which
                            // might cause disk corruption
                            *scratchcache = 0;
 
return 0x0ffffff7;      // FAT32 bad cluster    
                }
 
*scratchcache = sector;
 
}
 
 
            // At this point, we "merely" need to extract the relevant entry.
            // This is easy for FAT16 and FAT32, but a royal PITA for FAT12 as a single entry
            // may span a sector boundary. The normal way around this is always to read two
            // FAT sectors, but that luxury is (by design intent) unavailable to DOSFS.
            offset = ldiv(offset, SECTOR_SIZE).rem;
 
 
if (volinfo->filesystem == FAT12) {
 
                    // Special case for sector boundary - Store last byte of current sector.
                    // Then read in the next sector and put the first byte of that sector into
                    // the high byte of result.
                    if (offset == SECTOR_SIZE - 1) {
 
result = (unsigned long int)scratch[offset];
 
sector++;
 
if (DFS_ReadSector(volinfo->unit, scratch, sector, 1)) {
 
                                    // avoid anyone assuming that this cache value is still valid, which
                                    // might cause disk corruption
                                    *scratchcache = 0;
 
return 0x0ffffff7;      // FAT32 bad cluster    
                        }
 
*scratchcache = sector;
 
                            // Thanks to Claudio Leonel for pointing out this missing line.
                            result |= ((unsigned long int)scratch[0]) << 8;
 
}
 
                else {
 
result = (unsigned long int)scratch[offset] |
                            ((unsigned long int)scratch[offset + 1]) << 8;
 
}
if (cluster & 1)
 
result = result >> 4;
 
                else
 
result = result & 0xfff;
 
}
 
        else if (volinfo->filesystem == FAT16) {
 
result = (unsigned long int)scratch[offset] |
                    ((unsigned long int)scratch[offset + 1]) << 8;
 
}
 
        else if (volinfo->filesystem == FAT32) {
 
result = ((unsigned long int)scratch[offset] |
                           ((unsigned long int)scratch[offset + 1]) << 8 |
                           ((unsigned long int)scratch[offset + 2]) << 16 |
                           ((unsigned long int)scratch[offset + 3]) << 24) &
                    0x0fffffff;
 
}
 
        else
 
result = 0x0ffffff7;    // FAT32 bad cluster    
        return result;
 
}
 
 
 
 
/*
        Set FAT entry for specified cluster number
        You must provide a scratch buffer for one sector (SECTOR_SIZE) and a populated VOLINFO
        Returns DFS_ERRMISC for any error, otherwise DFS_OK
        scratchcache should point to a UINT32. This variable caches the physical sector number
        last read into the scratch buffer for performance enhancement reasons.
 
        NOTE: This code is HIGHLY WRITE-INEFFICIENT, particularly for flash media. Considerable
        performance gains can be realized by caching the sector. However this is difficult to
        achieve on FAT12 without requiring 2 sector buffers of scratch space, and it is a design
        requirement of this code to operate on a single 512-byte scratch.
 
        If you are operating DOSFS over flash, you are strongly advised to implement a writeback
        cache in your physical I/O driver. This will speed up your code significantly and will
        also conserve power and flash write life.
*/
unsigned long int DFS_SetFAT(PVOLINFO volinfo, unsigned char *scratch,
                             unsigned long int *scratchcache,
                             unsigned long int cluster,
                             unsigned long int new_contents)
{
 
unsigned long int offset, sector, result;
 
if (volinfo->filesystem == FAT12) {
 
offset = cluster + (cluster / 2);
 
new_contents &= 0xfff;
 
}
 
        else if (volinfo->filesystem == FAT16) {
 
offset = cluster * 2;
 
new_contents &= 0xffff;
 
}
 
        else if (volinfo->filesystem == FAT32) {
 
offset = cluster * 4;
 
new_contents &= 0x0fffffff;     // FAT32 is really "FAT28"
        }
 
        else
 
return DFS_ERRMISC;
 
 
            // at this point, offset is the BYTE offset of the desired sector from the start
            // of the FAT. Calculate the physical sector containing this FAT entry.
            sector = ldiv(offset, SECTOR_SIZE).quot + volinfo->fat1;
 
 
            // If this is not the same sector we last read, then read it into RAM
            if (sector != *scratchcache) {
 
if (DFS_ReadSector(volinfo->unit, scratch, sector, 1)) {
 
                            // avoid anyone assuming that this cache value is still valid, which
                            // might cause disk corruption
                            *scratchcache = 0;
 
return DFS_ERRMISC;
 
}
 
*scratchcache = sector;
 
}
 
 
            // At this point, we "merely" need to extract the relevant entry.
            // This is easy for FAT16 and FAT32, but a royal PITA for FAT12 as a single entry
            // may span a sector boundary. The normal way around this is always to read two
            // FAT sectors, but that luxury is (by design intent) unavailable to DOSFS.
            offset = ldiv(offset, SECTOR_SIZE).rem;
 
 
if (volinfo->filesystem == FAT12) {
 
 
                    // If this is an odd cluster, pre-shift the desired new contents 4 bits to
                    // make the calculations below simpler
                    if (cluster & 1)
 
new_contents = new_contents << 4;
 
 
                    // Special case for sector boundary
                    if (offset == SECTOR_SIZE - 1) {
 
 
                            // Odd cluster: High 12 bits being set
                            if (cluster & 1) {
 
scratch[offset] =
                                    (scratch[offset] & 0x0f) | new_contents &
                                    0xf0;
 
}
 
                            // Even cluster: Low 12 bits being set
                            else {
 
scratch[offset] = new_contents & 0xff;
 
}
 
result =
                            DFS_WriteSector(volinfo->unit, scratch,
                                            *scratchcache, 1);
 
                            // mirror the FAT into copy 2
                            if (DFS_OK == result)
 
result =
                                    DFS_WriteSector(volinfo->unit, scratch,
                                                    (*scratchcache) +
                                                    volinfo->secperfat, 1);
 
 
                            // If we wrote that sector OK, then read in the subsequent sector
                            // and poke the first byte with the remainder of this FAT entry.
                            if (DFS_OK == result) {
 
*scratchcache++;
 
result =
                                    DFS_ReadSector(volinfo->unit, scratch,
                                                   *scratchcache, 1);
 
if (DFS_OK == result) {
 
                                            // Odd cluster: High 12 bits being set
                                            if (cluster & 1) {
 
scratch[0] =
                                                    new_contents & 0xff00;
 
}
 
                                            // Even cluster: Low 12 bits being set
                                            else {
 
scratch[0] =
                                                    (scratch[0] & 0xf0) |
                                                    new_contents & 0x0f;
 
}
 
result =
                                            DFS_WriteSector(volinfo->unit,
                                                            scratch,
                                                            *scratchcache, 1);
 
                                            // mirror the FAT into copy 2
                                            if (DFS_OK == result)
 
result =
                                                    DFS_WriteSector(volinfo->
                                                                    unit,
                                                                    scratch,
                                                                    (*scratchcache)
                                                                    +
                                                                    volinfo->
                                                                    secperfat,
                                                                    1);
 
}
 
                                else {
 
                                            // avoid anyone assuming that this cache value is still valid, which
                                            // might cause disk corruption
                                            *scratchcache = 0;
 
}
 
}
 
}               // if (offset == SECTOR_SIZE - 1)
 
                    // Not a sector boundary. But we still have to worry about if it's an odd
                    // or even cluster number.
                    else {
 
                            // Odd cluster: High 12 bits being set
                            if (cluster & 1) {
 
scratch[offset] =
                                    (scratch[offset] & 0x0f) | new_contents &
                                    0xf0;
 
scratch[offset + 1] = new_contents & 0xff00;
 
}
 
                            // Even cluster: Low 12 bits being set
                            else {
 
scratch[offset] = new_contents & 0xff;
 
scratch[offset + 1] =
                                    (scratch[offset + 1] & 0xf0) | new_contents
                                    & 0x0f;
 
}
 
result =
                            DFS_WriteSector(volinfo->unit, scratch,
                                            *scratchcache, 1);
 
                            // mirror the FAT into copy 2
                            if (DFS_OK == result)
 
result =
                                    DFS_WriteSector(volinfo->unit, scratch,
                                                    (*scratchcache) +
                                                    volinfo->secperfat, 1);
 
}
 
}
 
        else if (volinfo->filesystem == FAT16) {
 
scratch[offset] = (new_contents & 0xff);
 
scratch[offset + 1] = (new_contents & 0xff00) >> 8;
 
result =
                    DFS_WriteSector(volinfo->unit, scratch, *scratchcache, 1);
 
                    // mirror the FAT into copy 2
                    if (DFS_OK == result)
 
result =
                            DFS_WriteSector(volinfo->unit, scratch,
                                            (*scratchcache) +
                                            volinfo->secperfat, 1);
 
}
 
        else if (volinfo->filesystem == FAT32) {
 
scratch[offset] = (new_contents & 0xff);
 
scratch[offset + 1] = (new_contents & 0xff00) >> 8;
 
scratch[offset + 2] = (new_contents & 0xff0000) >> 16;
 
scratch[offset + 3] =
                    (scratch[offset + 3] & 0xf0) | ((new_contents & 0x0f000000)
                                                    >> 24);
 
                    // Note well from the above: Per Microsoft's guidelines we preserve the upper
                    // 4 bits of the FAT32 cluster value. It's unclear what these bits will be used
                    // for; in every example I've encountered they are always zero.
                    result =
                    DFS_WriteSector(volinfo->unit, scratch, *scratchcache, 1);
 
                    // mirror the FAT into copy 2
                    if (DFS_OK == result)
 
result =
                            DFS_WriteSector(volinfo->unit, scratch,
                                            (*scratchcache) +
                                            volinfo->secperfat, 1);
 
}
 
        else
 
result = DFS_ERRMISC;
 
 
return result;
 
}
 
 
 
/*
        Convert a filename element from canonical (8.3) to directory entry (11) form
        src must point to the first non-separator character.
        dest must point to a 12-byte buffer.
*/
unsigned char *DFS_CanonicalToDir(unsigned char *dest, unsigned char *src)
{
 
unsigned char *destptr = dest;
 
 
memset(dest, ' ', 11);
 
dest[11] = 0;
 
 
while (*src && (*src != DIR_SEPARATOR) && (destptr - dest < 11)) {
 
if (*src >= 'a' && *src <= 'z') {
 
*destptr++ = (*src - 'a') + 'A';
 
src++;
 
}
 
                else if (*src == '.') {
 
src++;
 
destptr = dest + 8;
 
}
 
                else {
 
*destptr++ = *src++;
 
}
 
}
 
 
return dest;
 
}
 
 
 
/*
        Find the first unused FAT entry
        You must provide a scratch buffer for one sector (SECTOR_SIZE) and a populated VOLINFO
        Returns a FAT32 BAD_CLUSTER value for any error, otherwise the contents of the desired
        FAT entry.
        Returns FAT32 bad_sector (0x0ffffff7) if there is no free cluster available
*/
unsigned long int DFS_GetFreeFAT(PVOLINFO volinfo, unsigned char *scratch)
{
 
unsigned long int i, result = 0xffffffff, scratchcache = 0;
 
 
            // Search starts at cluster 2, which is the first usable cluster
            // NOTE: This search can't terminate at a bad cluster, because there might
            // legitimately be bad clusters on the disk.
            for (i = 2; i < volinfo->numclusters; i++) {
 
result = DFS_GetFAT(volinfo, scratch, &scratchcache, i);
 
if (!result) {
 
return i;
 
}
 
}
 
return 0x0ffffff7;      // Can't find a free cluster
}
 
 
 
 
/*
        Open a directory for enumeration by DFS_GetNextDirEnt
        You must supply a populated VOLINFO (see DFS_GetVolInfo)
        The empty string or a string containing only the directory separator are
        considered to be the root directory.
        Returns 0 OK, nonzero for any error.
*/
unsigned long int DFS_OpenDir(PVOLINFO volinfo, unsigned char *dirname,
                              PDIRINFO dirinfo)
{
 
            // Default behavior is a regular search for existing entries
            dirinfo->flags = 0;
 
 
if (!strlen((char *)dirname)
              || (strlen((char *)dirname) == 1
                  && dirname[0] == DIR_SEPARATOR)) {
 
if (volinfo->filesystem == FAT32) {
 
dirinfo->currentcluster = volinfo->rootdir;
 
dirinfo->currentsector = 0;
 
dirinfo->currententry = 0;
 
 
                            // read first sector of directory
                            return DFS_ReadSector(volinfo->unit,
                                                  dirinfo->scratch,
                                                  volinfo->dataarea +
                                                  ((volinfo->rootdir -
                                                    2) * volinfo->secperclus),
                                                  1);
 
}
 
                else {
 
dirinfo->currentcluster = 0;
 
dirinfo->currentsector = 0;
 
dirinfo->currententry = 0;
 
 
                            // read first sector of directory
                            return DFS_ReadSector(volinfo->unit,
                                                  dirinfo->scratch,
                                                  volinfo->rootdir, 1);
 
}
 
}
 
 
            // This is not the root directory. We need to find the start of this subdirectory.
            // We do this by devious means, using our own companion function DFS_GetNext.
            else {
 
unsigned char tmpfn[12];
 
unsigned char *ptr = dirname;
 
unsigned long int result;
 
DIRENT de;
 
 
if (volinfo->filesystem == FAT32) {
 
dirinfo->currentcluster = volinfo->rootdir;
 
dirinfo->currentsector = 0;
 
dirinfo->currententry = 0;
 
 
                            // read first sector of directory
                            if (DFS_ReadSector
                                (volinfo->unit, dirinfo->scratch,
                                 volinfo->dataarea +
                                 ((volinfo->rootdir - 2) * volinfo->secperclus),
                                 1))
 
return DFS_ERRMISC;
 
}
 
                else {
 
dirinfo->currentcluster = 0;
 
dirinfo->currentsector = 0;
 
dirinfo->currententry = 0;
 
 
                            // read first sector of directory
                            if (DFS_ReadSector
                                (volinfo->unit, dirinfo->scratch,
                                 volinfo->rootdir, 1))
 
return DFS_ERRMISC;
 
}
 
 
                    // skip leading path separators
                    while (*ptr == DIR_SEPARATOR && *ptr)
 
ptr++;
 
 
                    // Scan the path from left to right, finding the start cluster of each entry
                    // Observe that this code is inelegant, but obviates the need for recursion.
                    while (*ptr) {
 
DFS_CanonicalToDir(tmpfn, ptr);
 
 
de.name[0] = 0;
 
 
                        do {
 
result = DFS_GetNext(volinfo, dirinfo, &de);
 
} while (!result && memcmp2(de.name, tmpfn, 11));
 
 
if (!memcmp2(de.name, tmpfn, 11)
                              && ((de.attr & ATTR_DIRECTORY) ==
                                  ATTR_DIRECTORY)) {
 
if (volinfo->filesystem == FAT32) {
 
dirinfo->currentcluster =
                                            (unsigned long int)de.
                                            startclus_l_l |
 
((unsigned long int)de.
                                              startclus_l_h) << 8 |
((unsigned
                                                                       long int)
                                                                      de.
                                                                      startclus_h_l)
                                            << 16 |
((unsigned long int)de.
                                                      startclus_h_h) << 24;
 
}
 
                                else {
 
dirinfo->currentcluster =
                                            (unsigned long int)de.
                                            startclus_l_l |
 
((unsigned long int)de.
                                              startclus_l_h) << 8;
 
}
dirinfo->currentsector = 0;
 
dirinfo->currententry = 0;
 
 
if (DFS_ReadSector
                                      (volinfo->unit, dirinfo->scratch,
                                       volinfo->dataarea +
                                       ((dirinfo->currentcluster -
                                         2) * volinfo->secperclus), 1))
 
return DFS_ERRMISC;
 
}
 
                        else if (!memcmp2(de.name, tmpfn, 11)
                                 && !(de.attr & ATTR_DIRECTORY))
 
return DFS_NOTFOUND;
 
 
                            // seek to next item in list
                            while (*ptr != DIR_SEPARATOR && *ptr)
 
ptr++;
 
if (*ptr == DIR_SEPARATOR)
 
ptr++;
 
}
 
 
if (!dirinfo->currentcluster)
 
return DFS_NOTFOUND;
 
}
 
return DFS_OK;
 
}
 
 
 
/*
        Get next entry in opened directory structure. Copies fields into the dirent
        structure, updates dirinfo. Note that it is the _caller's_ responsibility to
        handle the '.' and '..' entries.
        A deleted file will be returned as a NULL entry (first char of filename=0)
        by this code. Filenames beginning with 0x05 will be translated to 0xE5
        automatically. Long file name entries will be returned as NULL.
        returns DFS_EOF if there are no more entries, DFS_OK if this entry is valid,
        or DFS_ERRMISC for a media error
*/
unsigned long int DFS_GetNext(PVOLINFO volinfo, PDIRINFO dirinfo,
                              PDIRENT dirent)
{
 
unsigned long int tempint;      // required by DFS_GetFAT
 
            // Do we need to read the next sector of the directory?
            if (dirinfo->currententry >= SECTOR_SIZE / sizeof(DIRENT)) {
 
dirinfo->currententry = 0;
 
dirinfo->currentsector++;
 
 
                    // Root directory; special case handling 
                    // Note that currentcluster will only ever be zero if both:
                    // (a) this is the root directory, and
                    // (b) we are on a FAT12/16 volume, where the root dir can't be expanded
                    if (dirinfo->currentcluster == 0) {
 
                            // Trying to read past end of root directory?
                            if (dirinfo->currentsector *
                                (SECTOR_SIZE / sizeof(DIRENT)) >=
                                volinfo->rootentries)
 
return DFS_EOF;
 
 
                            // Otherwise try to read the next sector
                            if (DFS_ReadSector
                                (volinfo->unit, dirinfo->scratch,
                                 volinfo->rootdir + dirinfo->currentsector, 1))
 
return DFS_ERRMISC;
 
}
 
 
                    // Normal handling
                    else {
 
if (dirinfo->currentsector >= volinfo->secperclus) {
 
dirinfo->currentsector = 0;
 
if ((dirinfo->currentcluster >= 0xff7
                                      && volinfo->filesystem == FAT12)
                                     ||
(dirinfo->currentcluster >= 0xfff7
                                          && volinfo->filesystem == FAT16)
                                     ||
(dirinfo->currentcluster >= 0x0ffffff7
                                          && volinfo->filesystem == FAT32)) {
 
 
                                            // We are at the end of the directory chain. If this is a normal
                                            // find operation, we should indicate that there is nothing more
                                            // to see.
                                            if (!
                                                (dirinfo->
                                                 flags & DFS_DI_BLANKENT))
 
return DFS_EOF;
 
 
                                            // On the other hand, if this is a "find free entry" search,
                                            // we need to tell the caller to allocate a new cluster
                                            else
 
return DFS_ALLOCNEW;
 
}
 
dirinfo->currentcluster =
                                    DFS_GetFAT(volinfo, dirinfo->scratch,
                                               &tempint,
                                               dirinfo->currentcluster);
 
}
 
if (DFS_ReadSector
                             (volinfo->unit, dirinfo->scratch,
                              volinfo->dataarea +
                              ((dirinfo->currentcluster -
                                2) * volinfo->secperclus) +
                              dirinfo->currentsector, 1))
 
return DFS_ERRMISC;
 
}
 
}
 
 
memcpy(dirent, &(((PDIRENT) dirinfo->scratch)[dirinfo->currententry]),
                 sizeof(DIRENT));
 
 
if (dirent->name[0] == 0) {       // no more files in this directory
                // If this is a "find blank" then we can reuse this name.
                if (dirinfo->flags & DFS_DI_BLANKENT)
 
return DFS_OK;
 
                else
 
return DFS_EOF;
 
}
 
 
if (dirent->name[0] == 0xe5)     // handle deleted file entries
                dirent->name[0] = 0;
 
        else if ((dirent->attr & ATTR_LONG_NAME) == ATTR_LONG_NAME)
 
dirent->name[0] = 0;
 
        else if (dirent->name[0] == 0x05)        // handle kanji filenames beginning with 0xE5
                dirent->name[0] = 0xe5;
 
 
dirinfo->currententry++;
 
 
return DFS_OK;
 
}
 
 
 
/*
        INTERNAL
        Find a free directory entry in the directory specified by path
        This function MAY cause a disk write if it is necessary to extend the directory
        size.
        Note - di.scratch must be preinitialized to point to a sector scratch buffer
        de is a scratch structure
        Returns DFS_ERRMISC if a new entry could not be located or created
        de is updated with the same return information you would expect from DFS_GetNext
*/
unsigned long int DFS_GetFreeDirEnt(PVOLINFO volinfo, unsigned char *path,
                                    PDIRINFO di, PDIRENT de)
{
 
unsigned long int tempclus, i;
 
 
if (DFS_OpenDir(volinfo, path, di))
 
return DFS_NOTFOUND;
 
 
            // Set "search for empty" flag so DFS_GetNext knows what we're doing
            di->flags |= DFS_DI_BLANKENT;
 
 
            // We seek through the directory looking for an empty entry
            // Note we are reusing tempclus as a temporary result holder.
            tempclus = 0;
 
        do {
 
tempclus = DFS_GetNext(volinfo, di, de);
 
 
                    // Empty entry found
                    if (tempclus == DFS_OK && (!de->name[0])) {
 
return DFS_OK;
 
}
 
 
                    // End of root directory reached
                    else if (tempclus == DFS_EOF)
 
return DFS_ERRMISC;
 
 
                else if (tempclus == DFS_ALLOCNEW) {
 
tempclus = DFS_GetFreeFAT(volinfo, di->scratch);
 
if (tempclus == 0x0ffffff7)
 
return DFS_ERRMISC;
 
 
                            // write out zeroed sectors to the new cluster
                            memset(di->scratch, 0, SECTOR_SIZE);
 
for (i = 0; i < volinfo->secperclus; i++) {
 
if (DFS_WriteSector
                                     (volinfo->unit, di->scratch,
                                      volinfo->dataarea +
                                      ((tempclus - 2) * volinfo->secperclus) +
                                      i, 1))
 
return DFS_ERRMISC;
 
}
 
                            // Point old end cluster to newly allocated cluster
                            i = 0;
 
DFS_SetFAT(volinfo, di->scratch, &i,
                                    di->currentcluster, tempclus);
 
 
                            // Update DIRINFO so caller knows where to place the new file                   
                            di->currentcluster = tempclus;
 
di->currentsector = 0;
 
di->currententry = 1;   // since the code coming after this expects to subtract 1
 
                            // Mark newly allocated cluster as end of chain                 
                            switch (volinfo->filesystem) {
 
case FAT12:
                                tempclus = 0xff8;
                                break;
 
case FAT16:
                                tempclus = 0xfff8;
                                break;
 
case FAT32:
                                tempclus = 0x0ffffff8;
                                break;
 
default:
                                return DFS_ERRMISC;
 
}
 
DFS_SetFAT(volinfo, di->scratch, &i,
                                    di->currentcluster, tempclus);
 
}
 
} while (!tempclus);
 
 
            // We shouldn't get here
            return DFS_ERRMISC;
 
}
 
 
 
/*
        Open a file for reading or writing. You supply populated VOLINFO, a path to the file,
        mode (DFS_READ or DFS_WRITE) and an empty fileinfo structure. You also need to
        provide a pointer to a sector-sized scratch buffer.
        Returns various DFS_* error states. If the result is DFS_OK, fileinfo can be used
        to access the file from this point on.
*/
unsigned long int DFS_OpenFile(PVOLINFO volinfo, unsigned char *path,
                               unsigned char mode, unsigned char *scratch,
                               PFILEINFO fileinfo)
{
 
unsigned char tmppath[MAX_PATH];
 
unsigned char filename[12];
 
unsigned char *p;
 
DIRINFO di;
 
DIRENT de;
 
 
            // larwe 2006-09-16 +1 zero out file structure
            memset(fileinfo, 0, sizeof(FILEINFO));
 
 
            // save access mode
            fileinfo->mode = mode;
 
 
            // Get a local copy of the path. If it's longer than MAX_PATH, abort.
            strcpy2((char *)tmppath, (char *)path);
 
tmppath[MAX_PATH - 1] = 0;
 
if (strcmp2((char *)path, (char *)tmppath)) {
 
return DFS_PATHLEN;
 
}
 
 
 
            // strip leading path separators
            while (tmppath[0] == DIR_SEPARATOR)
 
strcpy2((char *)tmppath, (char *)tmppath + 1);
 
 
            // Parse filename off the end of the supplied path
            p = tmppath;
 
while (*(p++)) ;
 
 
p--;
 
while (p > tmppath && *p != DIR_SEPARATOR)      // larwe 9/16/06 ">=" to ">" bugfix
                p--;
 
if (*p == DIR_SEPARATOR)
 
p++;
 
 
DFS_CanonicalToDir(filename, p);
 
 
if (p > tmppath)
 
p--;
 
if (*p == DIR_SEPARATOR || p == tmppath)        // larwe 9/16/06 +"|| p == tmppath" bugfix
                *p = 0;
 
 
            // At this point, if our path was MYDIR/MYDIR2/FILE.EXT, filename = "FILE    EXT" and
            // tmppath = "MYDIR/MYDIR2".
            di.scratch = scratch;
 
if (DFS_OpenDir(volinfo, tmppath, &di))
 
return DFS_NOTFOUND;
 
 
while (!DFS_GetNext(volinfo, &di, &de)) {
 
 
if (!memcmp2(de.name, filename, 11)) {
 
                            // You can't use this function call to open a directory.
                            if (de.attr & ATTR_DIRECTORY)
 
return DFS_NOTFOUND;
 
printf("get enxt \n");
 
fileinfo->volinfo = volinfo;
 
fileinfo->pointer = 0;
 
                            // The reason we store this extra info about the file is so that we can
                            // speedily update the file size, modification date, etc. on a file that is
                            // opened for writing.
                            if (di.currentcluster == 0)
 
fileinfo->dirsector =
                                    volinfo->rootdir + di.currentsector;
 
                        else
 
fileinfo->dirsector =
                                    volinfo->dataarea +
                                    ((di.currentcluster -
                                      2) * volinfo->secperclus) +
                                    di.currentsector;
 
fileinfo->diroffset = di.currententry - 1;
 
if (volinfo->filesystem == FAT32) {
 
fileinfo->cluster =
                                    (unsigned long int)de.
                                    startclus_l_l |
((unsigned long int)de.
                                                      startclus_l_h) << 8 |
 
((unsigned long int)de.
                                      startclus_h_l) << 16 |
((unsigned long
                                                                int)de.
                                                               startclus_h_h) <<
                                    24;
 
}
 
                        else {
 
fileinfo->cluster =
                                    (unsigned long int)de.
                                    startclus_l_l |
((unsigned long int)de.
                                                      startclus_l_h) << 8;
 
}
fileinfo->firstcluster = fileinfo->cluster;
 
fileinfo->filelen =
                            (unsigned long int)de.
                            filesize_0 |
((unsigned long int)de.
                                           filesize_1) << 8 |
((unsigned long
                                                                 int)de.
                                                                filesize_2) <<
                            16 |
((unsigned long int)de.filesize_3) << 24;
 
 
return DFS_OK;
 
}
 
}
 
 
            // At this point, we KNOW the file does not exist. If the file was opened
            // with write access, we can create it.
            if (mode & DFS_WRITE) {
 
unsigned long int cluster, temp;
 
 
                    // Locate or create a directory entry for this file
                    if (DFS_OK != DFS_GetFreeDirEnt(volinfo, tmppath, &di, &de))
 
return DFS_ERRMISC;
 
 
                    // put sane values in the directory entry
                    memset(&de, 0, sizeof(de));
 
memcpy(de.name, filename, 11);
 
de.crttime_l = 0x20;    // 01:01:00am, Jan 1, 2006.
                de.crttime_h = 0x08;
 
de.crtdate_l = 0x11;
 
de.crtdate_h = 0x34;
 
de.lstaccdate_l = 0x11;
 
de.lstaccdate_h = 0x34;
 
de.wrttime_l = 0x20;
 
de.wrttime_h = 0x08;
 
de.wrtdate_l = 0x11;
 
de.wrtdate_h = 0x34;
 
 
                    // allocate a starting cluster for the directory entry
                    cluster = DFS_GetFreeFAT(volinfo, scratch);
 
 
de.startclus_l_l = cluster & 0xff;
 
de.startclus_l_h = (cluster & 0xff00) >> 8;
 
de.startclus_h_l = (cluster & 0xff0000) >> 16;
 
de.startclus_h_h = (cluster & 0xff000000) >> 24;
 
 
                    // update FILEINFO for our caller's sake
                    fileinfo->volinfo = volinfo;
 
fileinfo->pointer = 0;
 
                    // The reason we store this extra info about the file is so that we can
                    // speedily update the file size, modification date, etc. on a file that is
                    // opened for writing.
                    if (di.currentcluster == 0)
 
fileinfo->dirsector =
                            volinfo->rootdir + di.currentsector;
 
                else
 
fileinfo->dirsector =
                            volinfo->dataarea +
                            ((di.currentcluster - 2) * volinfo->secperclus) +
                            di.currentsector;
 
fileinfo->diroffset = di.currententry - 1;
 
fileinfo->cluster = cluster;
 
fileinfo->firstcluster = cluster;
 
fileinfo->filelen = 0;
 
 
                    // write the directory entry
                    // note that we no longer have the sector containing the directory entry,
                    // tragically, so we have to re-read it
                    if (DFS_ReadSector
                        (volinfo->unit, scratch, fileinfo->dirsector, 1))
 
return DFS_ERRMISC;
 
memcpy(&(((PDIRENT) scratch)[di.currententry - 1]), &de,
                        sizeof(DIRENT));
 
if (DFS_WriteSector
                     (volinfo->unit, scratch, fileinfo->dirsector, 1))
 
return DFS_ERRMISC;
 
 
                    // Mark newly allocated cluster as end of chain                 
                    switch (volinfo->filesystem) {
 
case FAT12:
                        cluster = 0xff8;
                        break;
 
case FAT16:
                        cluster = 0xfff8;
                        break;
 
case FAT32:
                        cluster = 0x0ffffff8;
                        break;
 
default:
                        return DFS_ERRMISC;
 
}
 
temp = 0;
 
DFS_SetFAT(volinfo, scratch, &temp, fileinfo->cluster,
                            cluster);
 
 
return DFS_OK;
 
}
 
 
return DFS_NOTFOUND;
 
}
 
 
 
/*
        Read an open file
        You must supply a prepopulated FILEINFO as provided by DFS_OpenFile, and a
        pointer to a SECTOR_SIZE scratch buffer.
        Note that returning DFS_EOF is not an error condition. This function updates the
        successcount field with the number of bytes actually read.
*/
unsigned long int DFS_ReadFile(PFILEINFO fileinfo, unsigned char *scratch,
                               unsigned char *buffer,
                               unsigned long int *successcount,
                               unsigned long int len)
{
 
unsigned long int remain;
 
unsigned long int result = DFS_OK;
 
unsigned long int sector;
 
unsigned long int bytesread;
 
 
            // Don't try to read past EOF
            if (len > fileinfo->filelen - fileinfo->pointer)
 
len = fileinfo->filelen - fileinfo->pointer;
 
 
remain = len;
 
*successcount = 0;
 
 
while (remain && result == DFS_OK) {
 
                    // This is a bit complicated. The sector we want to read is addressed at a cluster
                    // granularity by the fileinfo->cluster member. The file pointer tells us how many
                    // extra sectors to add to that number.
                    sector = fileinfo->volinfo->dataarea +
                    ((fileinfo->cluster - 2) * fileinfo->volinfo->secperclus) +
 
div(div
                         (fileinfo->pointer,
                          fileinfo->volinfo->secperclus * SECTOR_SIZE).rem,
                         SECTOR_SIZE).quot;
 
 
                    // Case 1 - File pointer is not on a sector boundary
                    if (div(fileinfo->pointer, SECTOR_SIZE).rem) {
 
 
unsigned short tempreadsize;
 
 
 
                            // We always have to go through scratch in this case
                            result =
                            DFS_ReadSector(fileinfo->volinfo->unit, scratch,
                                           sector, 1);
 
 
                            // This is the number of bytes that we actually care about in the sector
                            // just read.
 
tempreadsize =
                            SECTOR_SIZE -
                            (div(fileinfo->pointer, SECTOR_SIZE).rem);
 
 
 
                            // Case 1A - We want the entire remainder of the sector. After this
                            // point, all passes through the read loop will be aligned on a sector
                            // boundary, which allows us to go through the optimal path 2A below.
                            if (remain >= tempreadsize) {
 
memcpy(buffer,
                                        scratch + (SECTOR_SIZE - tempreadsize),
                                        tempreadsize);
 
bytesread = tempreadsize;
 
buffer += tempreadsize;
 
fileinfo->pointer += tempreadsize;
 
remain -= tempreadsize;
 
}
 
                            // Case 1B - This read concludes the file read operation
                            else {
 
memcpy(buffer,
                                        scratch + (SECTOR_SIZE - tempreadsize),
                                        remain);
 
 
buffer += remain;
 
fileinfo->pointer += remain;
 
bytesread = remain;
 
remain = 0;
 
}
 
}
 
                    // Case 2 - File pointer is on sector boundary
                    else {
 
 
                            // Case 2A - We have at least one more full sector to read and don't have
                            // to go through the scratch buffer. You could insert optimizations here to
                            // read multiple sectors at a time, if you were thus inclined (note that
                            // the maximum multi-read you could perform is a single cluster, so it would
                            // be advantageous to have code similar to case 1A above that would round the
                            // pointer to a cluster boundary the first pass through, so all subsequent
                            // [large] read requests would be able to go a cluster at a time).
                            if (remain >= SECTOR_SIZE) {
 
 
result =
                                    DFS_ReadSector(fileinfo->volinfo->unit,
                                                   buffer, sector, 1);
 
 
remain -= SECTOR_SIZE;
 
 
buffer += SECTOR_SIZE;
 
 
fileinfo->pointer += SECTOR_SIZE;
 
 
bytesread = SECTOR_SIZE;
 
 
}
 
                            // Case 2B - We are only reading a partial sector
                            else {
 
 
result =
                                    DFS_ReadSector(fileinfo->volinfo->unit,
                                                   scratch, sector, 1);
 
memcpy(buffer, scratch, remain);
 
buffer += remain;
 
fileinfo->pointer += remain;
 
bytesread = remain;
 
remain = 0;
 
}
 
}
 
 
*successcount += bytesread;
 
 
 
                    // check to see if we stepped over a cluster boundary
                    if (div
                        (fileinfo->pointer - bytesread,
                         fileinfo->volinfo->secperclus * SECTOR_SIZE).quot !=
 
div(fileinfo->pointer,
                             fileinfo->volinfo->secperclus *
                             SECTOR_SIZE).quot) {
 
                            // An act of minor evil - we use bytesread as a scratch integer, knowing that
                            // its value is not used after updating *successcount above
 
bytesread = 0;
 
 
if (((fileinfo->volinfo->filesystem == FAT12)
                               && (fileinfo->cluster >= 0xff8))
                              ||
((fileinfo->volinfo->filesystem == FAT16)
                                   && (fileinfo->cluster >= 0xfff8))
                              ||
((fileinfo->volinfo->filesystem == FAT32)
                                   && (fileinfo->cluster >= 0x0ffffff8)))
 
result = DFS_EOF;
 
                        else
 
fileinfo->cluster =
                                    DFS_GetFAT(fileinfo->volinfo, scratch,
                                               &bytesread, fileinfo->cluster);
 
}
 
}
 
 
 
return result;
 
}
 
 
 
/*
        Seek file pointer to a given position
        This function does not return status - refer to the fileinfo->pointer value
        to see where the pointer wound up.
        Requires a SECTOR_SIZE scratch buffer
*/
void DFS_Seek(PFILEINFO fileinfo, unsigned long int offset,
              unsigned char *scratch)
{
 
unsigned long int tempint;
 
 
            // larwe 9/16/06 bugfix split case 0a/0b and changed fallthrough handling
            // Case 0a - Return immediately for degenerate case
            if (offset == fileinfo->pointer) {
 
return;
 
}
 
 
            // Case 0b - Don't allow the user to seek past the end of the file
            if (offset > fileinfo->filelen) {
 
offset = fileinfo->filelen;
 
                    // NOTE NO RETURN HERE!
        }
 
 
            // Case 1 - Simple rewind to start
            // Note _intentional_ fallthrough from Case 0b above
            if (offset == 0) {
 
fileinfo->cluster = fileinfo->firstcluster;
 
fileinfo->pointer = 0;
 
return; // larwe 9/16/06 +1 bugfix
        }
 
            // Case 2 - Seeking backwards. Need to reset and seek forwards
            else if (offset < fileinfo->pointer) {
 
fileinfo->cluster = fileinfo->firstcluster;
 
fileinfo->pointer = 0;
 
                    // NOTE NO RETURN HERE!
        }
 
 
            // Case 3 - Seeking forwards
            // Note _intentional_ fallthrough from Case 2 above
 
            // Case 3a - Seek size does not cross cluster boundary - 
            // very simple case
            // larwe 9/16/06 changed .rem to .quot in both div calls, bugfix
            if (div
                (fileinfo->pointer,
                 fileinfo->volinfo->secperclus * SECTOR_SIZE).quot ==
 
div(fileinfo->pointer + offset,
                     fileinfo->volinfo->secperclus * SECTOR_SIZE).quot) {
 
fileinfo->pointer = offset;
 
}
 
            // Case 3b - Seeking across cluster boundary(ies)
            else {
 
                    // round file pointer down to cluster boundary
                    fileinfo->pointer =
                    div(fileinfo->pointer,
                        fileinfo->volinfo->secperclus * SECTOR_SIZE).quot *
 
fileinfo->volinfo->secperclus * SECTOR_SIZE;
 
 
                    // seek by clusters
                    // larwe 9/30/06 bugfix changed .rem to .quot in both div calls
                    while (div
                           (fileinfo->pointer,
                            fileinfo->volinfo->secperclus * SECTOR_SIZE).quot !=
 
div(fileinfo->pointer + offset,
                                fileinfo->volinfo->secperclus *
                                SECTOR_SIZE).quot) {
 
 
fileinfo->cluster =
                            DFS_GetFAT(fileinfo->volinfo, scratch, &tempint,
                                       fileinfo->cluster);
 
                            // Abort if there was an error
                            if (fileinfo->cluster == 0x0ffffff7) {
 
fileinfo->pointer = 0;
 
fileinfo->cluster = fileinfo->firstcluster;
 
return;
 
}
 
fileinfo->pointer +=
                            SECTOR_SIZE * fileinfo->volinfo->secperclus;
 
}
 
 
                    // since we know the cluster is right, we have no more work to do
                    fileinfo->pointer = offset;
 
}
 
}
 
 
 
/*
        Delete a file
        scratch must point to a sector-sized buffer
*/
unsigned long int DFS_UnlinkFile(PVOLINFO volinfo, unsigned char *path,
                                 unsigned char *scratch)
{
 
PDIRENT de = (PDIRENT) scratch;
 
FILEINFO fi;
 
unsigned long int cache = 0;
 
unsigned long int tempclus;
 
 
            // DFS_OpenFile gives us all the information we need to delete it
            if (DFS_OK != DFS_OpenFile(volinfo, path, DFS_READ, scratch, &fi))
 
return DFS_NOTFOUND;
 
 
            // First, read the directory sector and delete that entry
            if (DFS_ReadSector(volinfo->unit, scratch, fi.dirsector, 1))
 
return DFS_ERRMISC;
 
((PDIRENT) scratch)[fi.diroffset].name[0] = 0xe5;
 
if (DFS_WriteSector(volinfo->unit, scratch, fi.dirsector, 1))
 
return DFS_ERRMISC;
 
 
            // Now follow the cluster chain to free the file space
            while (!
                   ((volinfo->filesystem == FAT12 && fi.firstcluster >= 0x0ff7)
                    ||
(volinfo->filesystem == FAT16
                         && fi.firstcluster >= 0xfff7)
                    ||
(volinfo->filesystem == FAT32
                         && fi.firstcluster >= 0x0ffffff7))) {
 
tempclus = fi.firstcluster;
 
 
fi.firstcluster =
                    DFS_GetFAT(volinfo, scratch, &cache, fi.firstcluster);
 
DFS_SetFAT(volinfo, scratch, &cache, tempclus, 0);
 
 
}
 
return DFS_OK;
 
}
 
 
 
 
/*
        Write an open file
        You must supply a prepopulated FILEINFO as provided by DFS_OpenFile, and a
        pointer to a SECTOR_SIZE scratch buffer.
        This function updates the successcount field with the number of bytes actually written.
*/
unsigned long int DFS_WriteFile(PFILEINFO fileinfo, unsigned char *scratch,
                                unsigned char *buffer,
                                unsigned long int *successcount,
                                unsigned long int len)
{
 
unsigned long int remain;
 
unsigned long int result = DFS_OK;
 
unsigned long int sector;
 
unsigned long int byteswritten;
 
 
            // Don't allow writes to a file that's open as readonly
            if (!(fileinfo->mode & DFS_WRITE))
 
return DFS_ERRMISC;
 
 
remain = len;
 
*successcount = 0;
 
 
while (remain && result == DFS_OK) {
 
                    // This is a bit complicated. The sector we want to read is addressed at a cluster
                    // granularity by the fileinfo->cluster member. The file pointer tells us how many
                    // extra sectors to add to that number.
                    sector = fileinfo->volinfo->dataarea +
                    ((fileinfo->cluster - 2) * fileinfo->volinfo->secperclus) +
 
div(div
                         (fileinfo->pointer,
                          fileinfo->volinfo->secperclus * SECTOR_SIZE).rem,
                         SECTOR_SIZE).quot;
 
 
                    // Case 1 - File pointer is not on a sector boundary
                    if (div(fileinfo->pointer, SECTOR_SIZE).rem) {
 
unsigned short tempsize;
 
printf("CASE 1 \n");
 
                            // We always have to go through scratch in this case
                            result =
                            DFS_ReadSector(fileinfo->volinfo->unit, scratch,
                                           sector, 1);
 
 
                            // This is the number of bytes that we don't want to molest in the
                            // scratch sector just read.
                            tempsize = div(fileinfo->pointer, SECTOR_SIZE).rem;
 
 
                            // Case 1A - We are writing the entire remainder of the sector. After
                            // this point, all passes through the read loop will be aligned on a
                            // sector boundary, which allows us to go through the optimal path
                            // 2A below.
                            if (remain >= SECTOR_SIZE - tempsize) {
 
memcpy(scratch + tempsize, buffer,
                                        SECTOR_SIZE - tempsize);
 
if (!result)
 
result =
                                            DFS_WriteSector(fileinfo->volinfo->
                                                            unit, scratch,
                                                            sector, 1);
 
 
byteswritten = SECTOR_SIZE - tempsize;
 
buffer += SECTOR_SIZE - tempsize;
 
fileinfo->pointer += SECTOR_SIZE - tempsize;
 
if (fileinfo->filelen < fileinfo->pointer) {
 
fileinfo->filelen = fileinfo->pointer;
 
}
 
remain -= SECTOR_SIZE - tempsize;
 
}
 
                            // Case 1B - This concludes the file write operation
                            else {
 
printf("CASE 1B \n");
 
memcpy(scratch + tempsize, buffer, remain);
 
if (!result)
 
result =
                                            DFS_WriteSector(fileinfo->volinfo->
                                                            unit, scratch,
                                                            sector, 1);
 
 
buffer += remain;
 
fileinfo->pointer += remain;
 
if (fileinfo->filelen < fileinfo->pointer) {
 
fileinfo->filelen = fileinfo->pointer;
 
}
 
byteswritten = remain;
 
remain = 0;
 
}
 
}               // case 1
                // Case 2 - File pointer is on sector boundary
                else {
 
printf("CASE 2 \n");
 
                            // Case 2A - We have at least one more full sector to write and don't have
                            // to go through the scratch buffer. You could insert optimizations here to
                            // write multiple sectors at a time, if you were thus inclined. Refer to
                            // similar notes in DFS_ReadFile.
                            if (remain >= SECTOR_SIZE) {
 
result =
                                    DFS_WriteSector(fileinfo->volinfo->unit,
                                                    buffer, sector, 1);
 
remain -= SECTOR_SIZE;
 
buffer += SECTOR_SIZE;
 
fileinfo->pointer += SECTOR_SIZE;
 
if (fileinfo->filelen < fileinfo->pointer) {
 
fileinfo->filelen = fileinfo->pointer;
 
}
 
byteswritten = SECTOR_SIZE;
 
}
 
                            // Case 2B - We are only writing a partial sector and potentially need to
                            // go through the scratch buffer.
                            else {
 
printf("CASE 2B \n");
 
                                    // If the current file pointer is not yet at or beyond the file
                                    // length, we are writing somewhere in the middle of the file and
                                    // need to load the original sector to do a read-modify-write.
                                    if (fileinfo->pointer < fileinfo->filelen) {
 
result =
                                            DFS_ReadSector(fileinfo->volinfo->
                                                           unit, scratch,
                                                           sector, 1);
 
if (!result) {
 
memcpy(scratch, buffer,
                                                        remain);
 
result =
                                                    DFS_WriteSector(fileinfo->
                                                                    volinfo->
                                                                    unit,
                                                                    scratch,
                                                                    sector, 1);
 
}
 
}
 
                                else {
 
result =
                                            DFS_WriteSector(fileinfo->volinfo->
                                                            unit, buffer,
                                                            sector, 1);
 
}
 
 
buffer += remain;
 
fileinfo->pointer += remain;
 
if (fileinfo->filelen < fileinfo->pointer) {
 
fileinfo->filelen = fileinfo->pointer;
 
}
 
byteswritten = remain;
 
remain = 0;
 
}
 
}
 
 
*successcount += byteswritten;
 
printf("Writen byte %d \n", *successcount);
 
                    // check to see if we stepped over a cluster boundary
                    if (div
                        (fileinfo->pointer - byteswritten,
                         fileinfo->volinfo->secperclus * SECTOR_SIZE).quot !=
 
div(fileinfo->pointer,
                             fileinfo->volinfo->secperclus *
                             SECTOR_SIZE).quot) {
 
unsigned long int lastcluster;
 
 
                            // We've transgressed into another cluster. If we were already at EOF,
                            // we need to allocate a new cluster.
                            // An act of minor evil - we use byteswritten as a scratch integer, knowing
                            // that its value is not used after updating *successcount above
                            byteswritten = 0;
 
 
lastcluster = fileinfo->cluster;
 
fileinfo->cluster =
                            DFS_GetFAT(fileinfo->volinfo, scratch,
                                       &byteswritten, fileinfo->cluster);
 
 
                            // Allocate a new cluster?
                            if (((fileinfo->volinfo->filesystem == FAT12)
                                 && (fileinfo->cluster >= 0xff8))
                                ||
((fileinfo->volinfo->filesystem == FAT16)
                                     && (fileinfo->cluster >= 0xfff8))
                                ||
((fileinfo->volinfo->filesystem == FAT32)
                                     && (fileinfo->cluster >= 0x0ffffff8))) {
 
unsigned long int tempclus;
 
 
tempclus =
                                    DFS_GetFreeFAT(fileinfo->volinfo, scratch);
 
byteswritten = 0;        // invalidate cache
                                if (tempclus == 0x0ffffff7)
 
return DFS_ERRMISC;
 
 
                                    // Link new cluster onto file
                                    DFS_SetFAT(fileinfo->volinfo, scratch,
                                               &byteswritten, lastcluster,
                                               tempclus);
 
fileinfo->cluster = tempclus;
 
 
                                    // Mark newly allocated cluster as end of chain                 
                                    switch (fileinfo->volinfo->filesystem) {
 
case FAT12:
                                        tempclus = 0xff8;
                                        break;
 
case FAT16:
                                        tempclus = 0xfff8;
                                        break;
 
case FAT32:
                                        tempclus = 0x0ffffff8;
                                        break;
 
default:
                                        return DFS_ERRMISC;
 
}
 
DFS_SetFAT(fileinfo->volinfo, scratch,
                                            &byteswritten, fileinfo->cluster,
                                            tempclus);
 
 
result = DFS_OK;
 
}
 
                            // No else clause is required.
                }
 
}
 
 
            // Update directory entry
            if (DFS_ReadSector
                (fileinfo->volinfo->unit, scratch, fileinfo->dirsector, 1))
 
return DFS_ERRMISC;
 
((PDIRENT) scratch)[fileinfo->diroffset].filesize_0 =
            fileinfo->filelen & 0xff;
 
((PDIRENT) scratch)[fileinfo->diroffset].filesize_1 =
            (fileinfo->filelen & 0xff00) >> 8;
 
((PDIRENT) scratch)[fileinfo->diroffset].filesize_2 =
            (fileinfo->filelen & 0xff0000) >> 16;
 
((PDIRENT) scratch)[fileinfo->diroffset].filesize_3 =
            (fileinfo->filelen & 0xff000000) >> 24;
 
if (DFS_WriteSector
             (fileinfo->volinfo->unit, scratch, fileinfo->dirsector, 1))
 
return DFS_ERRMISC;
 
return result;
 
}
 
 
 
int memcmp2(const void *s1, const void *s2, size_t n)
{
 
const unsigned char *p1 = s1, *p2 = s2;
 
while (n--)
 
if (*p1 != *p2)
 
return *p1 - *p2;
 
                else
 
*p1++, *p2++;
 
return 0;
 
}
 
 
 
char *strcpy2(char *dest, char *src)
{
 
char *ret = dest;
 
while (*dest++ = *src++)
 
;
 
return ret;
 
}
 
 
 
int strcmp2(const char *s1, const char *s2)
{
 
while (*s1 && (*s1 == *s2))
 
s1++, s2++;
 
return *(const unsigned char *)s1 - *(const unsigned char *)s2;
 
}
Browse

Tools

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [bootloaders/] [orpmon/] [common/] [dosfs.c] - Blame information for rev 743

Line No.	Rev	Author	Line
1	389	tac2	`/*`
2			`DOSFS Embedded FAT-Compatible Filesystem`
3			`(C) 2005 Lewin A.R.W. Edwards (sysadm@zws.com)`
4
5			`You are permitted to modify and/or use this code in your own projects without`
6			`payment of royalty, regardless of the license(s) you choose for those projects.`
7
8			`You cannot re-copyright or restrict use of the code as released by Lewin Edwards.`
9	406	julius	`*/`
10
11	389	tac2	`/*`
12			`@2010, adam.edvardsson@orsoc.se`
13			`Added local copy of the functions,`
14			`div_t, memcmp2,strcpy2,strcmp2. The one from the string library is not comatible`
15
16	406	julius	`*/`
17
18	389	tac2
19			`//#include <string.h>`
20			`//#include <stdlib.h>`
21			`//#include "or32_utils.h"`
22			`#include "dosfs.h"`
23			`#include "sdc.h"`
24	406	julius
25	389	tac2	`#include "common.h"`
26			`#include "support.h"`
27			`#include "uart.h"`
28	406	julius
29
30
31			`unsigned long int init_fat(VOLINFO * vis)`
32			`{`
33
34
35
36
37			`unsigned char sector[SECTOR_SIZE];`
38
39			`unsigned long int pstart, psize, i, fisz;`
40