#include <string.h>

#include "fsctl/fugue/sector.h"
#include "fsctl/fugue/utils.h"

//---
// Public
//---

/* fugue_sector_is_vbr() : check if the given address is a potential VBR */
int fugue_sector_is_vbr(struct fugue_fat_vbr *vbr)
{
    static const struct fugue_fat_vbr fugue_fat_vbr = {
        /* common boot information */
        .BS_jmpBoot = { 0xeb, 0x3c, 0x90 },
        .BS_OEMName = "MSDOS5.0",

        /* BIOS Parameter Block */
        .BPB_BytsPerSec = 512,
        .BPB_SecPerClus = 8,    // <--- not hardcoded by Casio
        .BPB_RsvdSecCnt = 0,    // <--- not hardcoded by Casio
        .BPB_NumFATs    = 2,
        .BPB_RootEntCnt = 0,    // <--- not hardcoded by Casio
        .BPB_TotSec16   = 0,    // <--- not hardcoded
        .BPB_Media      = 0xf8,
        .BPB_FATSz16    = 0,    // <--- not hardcoded
        .BPB_SecPerTrk  = 0,    // <--- not hardcoded
        .BPB_HiddSec    = 0,    // <--- not hardcoded
        .BPB_TotSec32   = 0,    // <--- not hardcoded

        /* Extended BIOS Parameter Block */
        .BS_DrvNum      = 0x80,
        .BS_Reserved1   = 0,
        .BS_BootSig     = 0x29,
        .BS_VolID       = {0x00, 0x00, 0x00, 0x00},
        .BS_VolLab      = "CASIO      ",
        .BS_FilSysType  = "FAT16   ",

        /* signature */
        .Signature_word = {0x55, 0xaa}
    };

    //---
    // VBR global hardcoded value check
    //---

    /* check common boot information */
    if (memcmp(vbr, &fugue_fat_vbr, 11) != 0)
        return -1;

    /* check BIOS Parameter Block */
    if (FAT_WORD(vbr->BPB_BytsPerSec) != fugue_fat_vbr.BPB_BytsPerSec)
        return -1;
    if (vbr->BPB_NumFATs != fugue_fat_vbr.BPB_NumFATs)
        return -1;
    if (vbr->BPB_Media != fugue_fat_vbr.BPB_Media)
        return -1;

    /* check Extended BIOS Parameter Block */
    if (memcmp(&(vbr->BS_DrvNum), &(fugue_fat_vbr.BS_DrvNum), 474) != 0)
        return -1;

    /* check signature */
    if (vbr->Signature_word[0] != fugue_fat_vbr.Signature_word[0])
        return -1;
    if (vbr->Signature_word[1] != fugue_fat_vbr.Signature_word[1])
        return -1;

    //---
    // FAT validity check
    //---

    return 0;
}

/* fugue_sector_is_invalid() : check if the sector is invalide */
int fugue_sector_is_invalid(void *sector)
{
    int x;

    for (x = 0 ; x < 512 / 2 ; x++)
    {
        if (((uint32_t *)sector)[x] != 0xffffffff)
            break;
    }
    if (x >= (512 / 4))
        return -1;
    return 0;
}