90 lines
2.4 KiB
C
90 lines
2.4 KiB
C
#include <string.h>
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#include "fsctl/fugue/sector.h"
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#include "fsctl/fugue/utils.h"
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//---
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// Public
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//---
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/* fugue_sector_is_vbr() : check if the given address is a potential VBR */
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int fugue_sector_is_vbr(struct fugue_fat_vbr *vbr)
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{
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static const struct fugue_fat_vbr fugue_fat_vbr = {
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/* common boot information */
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.BS_jmpBoot = { 0xeb, 0x3c, 0x90 },
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.BS_OEMName = "MSDOS5.0",
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/* BIOS Parameter Block */
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.BPB_BytsPerSec = 512,
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.BPB_SecPerClus = 8, // <--- not hardcoded by Casio
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.BPB_RsvdSecCnt = 0, // <--- not hardcoded by Casio
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.BPB_NumFATs = 2,
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.BPB_RootEntCnt = 0, // <--- not hardcoded by Casio
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.BPB_TotSec16 = 0, // <--- not hardcoded
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.BPB_Media = 0xf8,
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.BPB_FATSz16 = 0, // <--- not hardcoded
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.BPB_SecPerTrk = 0, // <--- not hardcoded
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.BPB_HiddSec = 0, // <--- not hardcoded
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.BPB_TotSec32 = 0, // <--- not hardcoded
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/* Extended BIOS Parameter Block */
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.BS_DrvNum = 0x80,
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.BS_Reserved1 = 0,
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.BS_BootSig = 0x29,
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.BS_VolID = {0x00, 0x00, 0x00, 0x00},
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.BS_VolLab = "CASIO ",
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.BS_FilSysType = "FAT16 ",
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/* signature */
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.Signature_word = {0x55, 0xaa}
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};
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//---
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// VBR global hardcoded value check
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//---
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/* check common boot information */
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if (memcmp(vbr, &fugue_fat_vbr, 11) != 0)
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return -1;
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/* check BIOS Parameter Block */
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if (FAT_WORD(vbr->BPB_BytsPerSec) != fugue_fat_vbr.BPB_BytsPerSec)
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return -1;
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if (vbr->BPB_NumFATs != fugue_fat_vbr.BPB_NumFATs)
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return -1;
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if (vbr->BPB_Media != fugue_fat_vbr.BPB_Media)
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return -1;
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/* check Extended BIOS Parameter Block */
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if (memcmp(&(vbr->BS_DrvNum), &(fugue_fat_vbr.BS_DrvNum), 474) != 0)
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return -1;
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/* check signature */
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if (vbr->Signature_word[0] != fugue_fat_vbr.Signature_word[0])
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return -1;
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if (vbr->Signature_word[1] != fugue_fat_vbr.Signature_word[1])
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return -1;
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//---
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// FAT validity check
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//---
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return 0;
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}
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/* fugue_sector_is_invalid() : check if the sector is invalide */
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int fugue_sector_is_invalid(void *sector)
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{
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int x;
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for (x = 0 ; x < 512 / 2 ; x++)
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{
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if (((uint32_t *)sector)[x] != 0xffffffff)
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break;
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}
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if (x >= (512 / 4))
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return -1;
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return 0;
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}
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