up_deviceimage.c

這是一個實時嵌入式作業系統 實作了MCS51 ARM等MCU

    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0xe0, 0x77, 0x7d, 0x06
};


/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: up_deviceimage
 *
 * Description: Return an allocated buffer representing an in-memory VFAT
 *   file system.
 *
 ****************************************************************************/

char *up_deviceimage(void)
{
    char    *pbuffer;
    int      bufsize = 1024*1024;
    int      offset  = 0;
    z_stream strm;
    int      ret;

    /* Ininitilize inflate state */

    strm.zalloc   = Z_NULL;
    strm.zfree    = Z_NULL;
    strm.opaque   = Z_NULL;
    strm.avail_in = 0;
    strm.next_in  = Z_NULL;
    ret           = inflateInit(&strm);
    if (ret != Z_OK)
      {
        sdbg("inflateInit FAILED: ret=%d msg=\"%s\"\n", ret, strm.msg ? strm.msg : "No message" );
        return NULL;
      }

    /* Allocate a buffer to hold the decompressed buffer.  We may have
     * to reallocate this a few times to get the size right.
     */
    pbuffer = (char*)malloc(bufsize);

    /* Set up the input buffer */

    strm.avail_in = sizeof(g_vfatdata);
    strm.next_in = (Bytef*)g_vfatdata;

    /* Run inflate() on input until output buffer not full */

    do {
        /* Set up to catch the next output chunk in the output buffer */

        strm.avail_out = bufsize - offset;
        strm.next_out  = (Bytef*)&pbuffer[offset];

        /* inflate */

        ret = inflate(&strm, Z_NO_FLUSH);

        /* Handle inflate() error return values */

        switch (ret)
          {
            case Z_NEED_DICT:
            case Z_DATA_ERROR:
            case Z_MEM_ERROR:
            case Z_STREAM_ERROR:
                sdbg("inflate FAILED: ret=%d msg=\"%s\"\n", ret, strm.msg ? strm.msg : "No message" );
                (void)inflateEnd(&strm);
                free(pbuffer);
                return NULL;
          }

        /* If avail_out is zero, then inflate() returned only
         * because it is out of buffer space.  In this case, we
         * will have to reallocate the buffer and try again.
         */

        if (strm.avail_out == 0)
          {
            int newbufsize = bufsize + 128*1024;
            char *newbuffer = realloc(pbuffer, newbufsize);
            if (!newbuffer)
              {
                free(pbuffer);
                return NULL;
              }
            else
              {
                pbuffer = newbuffer;
                offset  = bufsize;
                bufsize = newbufsize;
              }
          }
        else
          {
             /* There are unused bytes in the buffer, reallocate to
              * correct size.
              */

             int newbufsize = bufsize - strm.avail_out;
             char *newbuffer = realloc(pbuffer, newbufsize);
             if (!newbuffer)
               {
                free(pbuffer);
                return NULL;
              }
            else
              {
                pbuffer = newbuffer;
                bufsize = newbufsize;
              }
          }
    } while (strm.avail_out == 0 && ret != Z_STREAM_END);

    (void)inflateEnd(&strm);
    return pbuffer;
}

/****************************************************************************
 * Name: main
 *
 * Description: Used to test decompression logic
 *
 *  gcc -g -Wall -DVFAT_STANDALONE -lz -o vfat-test up_deviceimage.c
 *
 ****************************************************************************/

#ifdef VFAT_STANDALONE
int main(int argc, char **argv, char **envp)
{
    char *deviceimage;
    int cmf;
    int fdict;
    int flg;
    int check;

    cmf = g_vfatdata[0];
    printf("CMF=%02x: CM=%d CINFO=%d\n", cmf, cmf &0x0f, cmf >> 4);

    flg   = g_vfatdata[1];
    fdict = (flg >> 5) & 1;

    printf("FLG=%02x: FCHECK=%d FDICT=%d FLEVEL=%d\n", flg, flg &0x1f, fdict, flg >> 6);

    /* The FCHECK value must be such that CMF and FLG, when viewed as
     * a 16-bit unsigned integer stored in MSB order (CMF*256 + FLG),
     * is a multiple of 31.
     */

    check = cmf*256 + flg;
    if (check % 31 != 0)
    {
        printf("Fails check: %04x is not a multiple of 31\n", check);
    }

    deviceimage = up_deviceimage();
    if (deviceimage)
    {
        printf("Inflate SUCCEEDED\n");
        free(deviceimage);
        return 0;
    }
    else
    {
        printf("Inflate FAILED\n");
        return 1;
    }
}
#endif