-/*
- * Get the entry at index 'entry' in a FAT (12/16/32) table.
- * On failure 0x00 is returned.
- * When bufnum is changed, write back the previous fatbuf to the disk.
- */
-static __u32 get_fatent_value(fsdata *mydata, __u32 entry)
-{
- __u32 bufnum;
- __u32 off16, offset;
- __u32 ret = 0x00;
- __u16 val1, val2;
-
- if (CHECK_CLUST(entry, mydata->fatsize)) {
- printf("Error: Invalid FAT entry: 0x%08x\n", entry);
- return ret;
- }
-
- switch (mydata->fatsize) {
- case 32:
- bufnum = entry / FAT32BUFSIZE;
- offset = entry - bufnum * FAT32BUFSIZE;
- break;
- case 16:
- bufnum = entry / FAT16BUFSIZE;
- offset = entry - bufnum * FAT16BUFSIZE;
- break;
- case 12:
- bufnum = entry / FAT12BUFSIZE;
- offset = entry - bufnum * FAT12BUFSIZE;
- break;
-
- default:
- /* Unsupported FAT size */
- return ret;
- }
-
- debug("FAT%d: entry: 0x%04x = %d, offset: 0x%04x = %d\n",
- mydata->fatsize, entry, entry, offset, offset);
-
- /* Read a new block of FAT entries into the cache. */
- if (bufnum != mydata->fatbufnum) {
- int getsize = FATBUFBLOCKS;
- __u8 *bufptr = mydata->fatbuf;
- __u32 fatlength = mydata->fatlength;
- __u32 startblock = bufnum * FATBUFBLOCKS;
-
- if (getsize > fatlength)
- getsize = fatlength;
-
- fatlength *= mydata->sect_size; /* We want it in bytes now */
- startblock += mydata->fat_sect; /* Offset from start of disk */
-
- /* Write back the fatbuf to the disk */
- if (mydata->fatbufnum != -1) {
- if (flush_fat_buffer(mydata) < 0)
- return -1;
- }
-
- if (disk_read(startblock, getsize, bufptr) < 0) {
- debug("Error reading FAT blocks\n");
- return ret;
- }
- mydata->fatbufnum = bufnum;
- }
-
- /* Get the actual entry from the table */
- switch (mydata->fatsize) {
- case 32:
- ret = FAT2CPU32(((__u32 *) mydata->fatbuf)[offset]);
- break;
- case 16:
- ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[offset]);
- break;
- case 12:
- off16 = (offset * 3) / 4;
-
- switch (offset & 0x3) {
- case 0:
- ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[off16]);
- ret &= 0xfff;
- break;
- case 1:
- val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
- val1 &= 0xf000;
- val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
- val2 &= 0x00ff;
- ret = (val2 << 4) | (val1 >> 12);
- break;
- case 2:
- val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
- val1 &= 0xff00;
- val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
- val2 &= 0x000f;
- ret = (val2 << 8) | (val1 >> 8);
- break;
- case 3:
- ret = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
- ret = (ret & 0xfff0) >> 4;
- break;
- default:
- break;
- }
- break;
- }
- debug("FAT%d: ret: %08x, entry: %08x, offset: %04x\n",
- mydata->fatsize, ret, entry, offset);
-
- return ret;
-}
-