diskio_emul.c

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/*-----------------------------------------------------------------------*/
/* Low level disk I/O module skeleton for FatFs     (C)ChaN, 2007        */
/*-----------------------------------------------------------------------*/

#include <fs/fatfs/diskio.h>
#include <stdio.h>
#include <errno.h>
#include <time.h>

#define SECTOR_SIZE 512

static volatile DSTATUS Stat = STA_NOINIT;

/*-----------------------------------------------------------------------*/
/* Inidialize a Drive                                                    */

static FILE *fake_disk = 0;

DSTATUS disk_initialize (
    BYTE drv                /* Physical drive nmuber (0..) */
)
{
    if (drv)
        return STA_NOINIT; /* Support only drive 0 */
    // XXX: pay attention here: some functions call disk_initialize *after* it has
    //  been initialized for the first time.
    //  Here we just return the status (that should always be ~STA_NOINIT after the first
    //  call)
    if (fake_disk)
        return Stat;

    const char *path = "emuldisk.dsk";
    fake_disk = fopen(path, "w+");
    int err = errno;
    if (!fake_disk)
    {
        switch (err)
        {
        case EINVAL:
            fprintf(stderr, "invalid mode\n");
        default:
            return STA_NOINIT;
        }
    }
    Stat &= ~STA_NOINIT;
    return Stat;
}



/*-----------------------------------------------------------------------*/
/* Return Disk Status                                                    */

DSTATUS disk_status (
    BYTE drv        /* Physical drive nmuber (0..) */
)
{
    if (drv)
        return STA_NOINIT; /* Support only drive 0 */
    return Stat;
}



/*-----------------------------------------------------------------------*/
/* Read Sector(s)                                                        */

DRESULT disk_read (
    BYTE drv,       /* Physical drive nmuber (0..) */
    BYTE *buff,     /* Data buffer to store read data */
    DWORD sector,   /* Sector address (LBA) */
    BYTE count      /* Number of sectors to read (1..255) */
)
{
    if (drv || !count) return RES_PARERR;
    if (Stat & STA_NOINIT) return RES_NOTRDY;

    fseek(fake_disk, sector * SECTOR_SIZE, SEEK_SET);
    size_t read_items = fread(buff, SECTOR_SIZE, count, fake_disk);
    if (read_items == count)
        return RES_OK;
    else
    {
        if (feof(fake_disk))
            fprintf(stderr, "end-of-file\n");
        if (ferror(fake_disk))
            fprintf(stderr, "error\n");
        return RES_ERROR;
    }
}


/*-----------------------------------------------------------------------*/
/* Write Sector(s)                                                       */

#if _READONLY == 0
DRESULT disk_write (
    BYTE drv,           /* Physical drive nmuber (0..) */
    const BYTE *buff,   /* Data to be written */
    DWORD sector,       /* Sector address (LBA) */
    BYTE count          /* Number of sectors to write (1..255) */
)
{
    if (drv || !count) return RES_PARERR;
    if (Stat & STA_NOINIT) return RES_NOTRDY;
    if (Stat & STA_PROTECT) return RES_WRPRT;

    fseek(fake_disk, sector * SECTOR_SIZE, SEEK_SET);
    size_t write_items = fwrite(buff, SECTOR_SIZE, count, fake_disk);
    if (write_items == count)
        return RES_OK;
    else
    {
        if (feof(fake_disk))
            fprintf(stderr, "end-of-file\n");
        if (ferror(fake_disk))
            fprintf(stderr, "error\n");
        return RES_ERROR;
    }
}
#endif /* _READONLY */



/*-----------------------------------------------------------------------*/
/* Miscellaneous Functions                                               */

DRESULT disk_ioctl (
    BYTE drv,       /* Physical drive nmuber (0..) */
    BYTE ctrl,      /* Control code */
    void *buff      /* Buffer to send/receive control data */
)
{
    if (drv) return RES_PARERR;
    if (Stat & STA_NOINIT) return RES_NOTRDY;

    switch (ctrl)
    {
    case GET_SECTOR_SIZE:
        *(WORD*)buff = SECTOR_SIZE;
        break;
    case GET_SECTOR_COUNT:
        *(DWORD*)buff = 65536;
        break;
    case GET_BLOCK_SIZE:
        *(DWORD*)buff = 1;
        break;
    case CTRL_SYNC:
        fflush(fake_disk);
        break;
    default:
        return RES_PARERR;
    }
    return RES_OK;
}

DWORD get_fattime(void)
{
    time_t tmp = time(0);
    struct tm *t = localtime(&tmp);
    DWORD tim = 0;
    // seconds
    tim |= (t->tm_sec / 2);
    // min
    tim |= (t->tm_min << 5);
    // hour
    tim |= (t->tm_hour << 11);
    // month day (1..31)
    tim |= (t->tm_mday << 16);
    // month (1..12)
    tim |= ((t->tm_mon + 1) << 21);
    // year (0..127)
    tim |= ((t->tm_year - 80) << 25);
    return tim;
}