sd_raw.c

AVR读取SD卡里FAT格式内容的源程序

            /* let card some time to finish */
            sd_raw_rec_byte();
        }
#if !SD_RAW_SAVE_RAM
        else
        {
            /* use cached data */
            memcpy(buffer, raw_block + block_offset, read_length);
            buffer += read_length;
        }
#endif

        length -= read_length;
        offset += read_length;
    }

    return 1;
}

/**
 * \ingroup sd_raw
 * Continuously reads units of \c interval bytes and calls a callback function.
 *
 * This function starts reading at the specified offset. Every \c interval bytes,
 * it calls the callback function with the associated data buffer.
 *
 * By returning zero, the callback may stop reading.
 *
 * \note Within the callback function, you can not start another read or
 *       write operation.
 * \note This function only works if the following conditions are met:
 *       - (offset - (offset % 512)) % interval == 0
 *       - length % interval == 0
 *
 * \param[in] offset Offset from which to start reading.
 * \param[in] buffer Pointer to a buffer which is at least interval bytes in size.
 * \param[in] interval Number of bytes to read before calling the callback function.
 * \param[in] length Number of bytes to read altogether.
 * \param[in] callback The function to call every interval bytes.
 * \param[in] p An opaque pointer directly passed to the callback function.
 * \returns 0 on failure, 1 on success
 * \see sd_raw_write_interval, sd_raw_read, sd_raw_write
 */
uint8_t sd_raw_read_interval(uint32_t offset, uint8_t* buffer, uint16_t interval, uint16_t length, sd_raw_read_interval_handler_t callback, void* p)
{
    if(!buffer || interval == 0 || length < interval || !callback)
        return 0;

#if !SD_RAW_SAVE_RAM
    while(length >= interval)
    {
        /* as reading is now buffered, we directly
         * hand over the request to sd_raw_read()
         */
        if(!sd_raw_read(offset, buffer, interval))
            return 0;
        if(!callback(buffer, offset, p))
            break;
        offset += interval;
        length -= interval;
    }

    return 1;
#else
    /* address card */
    select_card();

    uint16_t block_offset;
    uint16_t read_length;
    uint8_t* buffer_cur;
    uint8_t finished = 0;
    do
    {
        /* determine byte count to read at once */
        block_offset = offset & 0x01ff;
        read_length = 512 - block_offset;
        
        /* send single block request */
        if(sd_raw_send_command_r1(CMD_READ_SINGLE_BLOCK, offset & 0xfffffe00))
        {
            unselect_card();
            return 0;
        }

        /* wait for data block (start byte 0xfe) */
        while(sd_raw_rec_byte() != 0xfe);

        /* read up to the data of interest */
        for(uint16_t i = 0; i < block_offset; ++i)
            sd_raw_rec_byte();

        /* read interval bytes of data and execute the callback */
        do
        {
            if(read_length < interval || length < interval)
                break;

            buffer_cur = buffer;
            for(uint16_t i = 0; i < interval; ++i)
                *buffer_cur++ = sd_raw_rec_byte();

            if(!callback(buffer, offset + (512 - read_length), p))
            {
                finished = 1;
                break;
            }

            read_length -= interval;
            length -= interval;

        } while(read_length > 0 && length > 0);
        
        /* read rest of data block */
        while(read_length-- > 0)
            sd_raw_rec_byte();
        
        /* read crc16 */
        sd_raw_rec_byte();
        sd_raw_rec_byte();

        if(length < interval)
            break;

        offset = (offset & 0xfffffe00) + 512;

    } while(!finished);
    
    /* deaddress card */
    unselect_card();

    /* let card some time to finish */
    sd_raw_rec_byte();

    return 1;
#endif
}

/**
 * \ingroup sd_raw
 * Writes raw data to the card.
 *
 * \note If write buffering is enabled, you might have to
 *       call sd_raw_sync() before disconnecting the card
 *       to ensure all remaining data has been written.
 *
 * \param[in] offset The offset where to start writing.
 * \param[in] buffer The buffer containing the data to be written.
 * \param[in] length The number of bytes to write.
 * \returns 0 on failure, 1 on success.
 * \see sd_raw_write_interval, sd_raw_read, sd_raw_read_interval
 */
uint8_t sd_raw_write(uint32_t offset, const uint8_t* buffer, uint16_t length)
{
#if SD_RAW_WRITE_SUPPORT

  ////  if(get_pin_locked())
  ////      return 0;

    uint32_t block_address;
    uint16_t block_offset;
    uint16_t write_length;
    while(length > 0)
    {
        /* determine byte count to write at once */
        block_address = offset & 0xfffffe00;
        block_offset = offset & 0x01ff;
        write_length = 512 - block_offset; /* write up to block border */
        if(write_length > length)
            write_length = length;
        
        /* Merge the data to write with the content of the block.
         * Use the cached block if available.
         */
        if(block_address != raw_block_address)
        {
#if SD_RAW_WRITE_BUFFERING
            if(!raw_block_written)
            {
                if(!sd_raw_write(raw_block_address, raw_block, sizeof(raw_block)))
                    return 0;
            }
#endif

            if(block_offset || write_length < 512)
            {
                if(!sd_raw_read(block_address, raw_block, sizeof(raw_block)))
                    return 0;
            }
            raw_block_address = block_address;
        }

        if(buffer != raw_block)
        {
            memcpy(raw_block + block_offset, buffer, write_length);

#if SD_RAW_WRITE_BUFFERING
            raw_block_written = 0;

            if(length == write_length)
                return 1;
#endif
        }

        buffer += write_length;

        /* address card */
        select_card();

        /* send single block request */
        if(sd_raw_send_command_r1(CMD_WRITE_SINGLE_BLOCK, block_address))
        {
            unselect_card();
            return 0;
        }

        /* send start byte */
        sd_raw_send_byte(0xfe);

        /* write byte block */
        uint8_t* cache = raw_block;
        for(uint16_t i = 0; i < 512; ++i)
            sd_raw_send_byte(*cache++);

        /* write dummy crc16 */
        sd_raw_send_byte(0xff);
        sd_raw_send_byte(0xff);

        /* wait while card is busy */
        while(sd_raw_rec_byte() != 0xff);
        sd_raw_rec_byte();

        /* deaddress card */
        unselect_card();

        length -= write_length;
        offset += write_length;

#if SD_RAW_WRITE_BUFFERING
        raw_block_written = 1;
#endif
    }
    
    return 1;
#else
    return 0;
#endif
}

/**
 * \ingroup sd_raw
 * Writes a continuous data stream obtained from a callback function.
 *
 * This function starts writing at the specified offset. To obtain the
 * next bytes to write, it calls the callback function. The callback fills the
 * provided data buffer and returns the number of bytes it has put into the buffer.
 *
 * By returning zero, the callback may stop writing.
 *
 * \param[in] offset Offset where to start writing.
 * \param[in] buffer Pointer to a buffer which is used for the callback function.
 * \param[in] length Number of bytes to write in total. May be zero for endless writes.
 * \param[in] callback The function used to obtain the bytes to write.
 * \param[in] p An opaque pointer directly passed to the callback function.
 * \returns 0 on failure, 1 on success
 * \see sd_raw_read_interval, sd_raw_write, sd_raw_read
 */
uint8_t sd_raw_write_interval(uint32_t offset, uint8_t* buffer, uint16_t length, sd_raw_write_interval_handler_t callback, void* p)
{
#if SD_RAW_WRITE_SUPPORT

#if SD_RAW_SAVE_RAM
    #error "SD_RAW_WRITE_SUPPORT is not supported together with SD_RAW_SAVE_RAM"
#endif

    if(!buffer || !callback)
        return 0;

    uint8_t endless = (length == 0);
    while(endless || length > 0)
    {
        uint16_t bytes_to_write = callback(buffer, offset, p);
        if(!bytes_to_write)
            break;
        if(!endless && bytes_to_write > length)
            return 0;

        /* as writing is always buffered, we directly
         * hand over the request to sd_raw_write()
         */
        if(!sd_raw_write(offset, buffer, bytes_to_write))
            return 0;

        offset += bytes_to_write;
        length -= bytes_to_write;
    }

    return 1;

#else
    return 0;
#endif
}

/**
 * \ingroup sd_raw
 * Writes the write buffer's content to the card.
 *
 * \note When write buffering is enabled, you should
 *       call this function before disconnecting the
 *       card to ensure all remaining data has been
 *       written.
 *
 * \returns 0 on failure, 1 on success.
 * \see sd_raw_write
 */
uint8_t sd_raw_sync()
{
#if SD_RAW_WRITE_SUPPORT
#if SD_RAW_WRITE_BUFFERING
    if(raw_block_written)
        return 1;
    if(!sd_raw_write(raw_block_address, raw_block, sizeof(raw_block)))
        return 0;
#endif
    return 1;
#else
    return 0;
#endif
}

/**
 * \ingroup sd_raw
 * Reads informational data from the card.
 *
 * This function reads and returns the card's registers
 * containing manufacturing and status information.
 *
 * \note: The information retrieved by this function is
 *        not required in any way to operate on the card,
 *        but it might be nice to display some of the data
 *        to the user.
 *
 * \param[in] info A pointer to the structure into which to save the information.
 * \returns 0 on failure, 1 on success.
 */
uint8_t sd_raw_get_info(struct sd_raw_info* info)
{
    if(!info || !sd_raw_available())
        return 0;

    memset(info, 0, sizeof(*info));

    select_card();

    /* read cid register */
    if(sd_raw_send_command_r1(CMD_SEND_CID, 0))
    {
        unselect_card();
        return 0;
    }
    while(sd_raw_rec_byte() != 0xfe);
    for(uint8_t i = 0; i < 18; ++i)
    {
        uint8_t b = sd_raw_rec_byte();

        switch(i)
        {
            case 0:
                info->manufacturer = b;
                break;
            case 1:
            case 2:
                info->oem[i - 1] = b;
                break;
            case 3:
            case 4:
            case 5:
            case 6:
            case 7:
                info->product[i - 3] = b;
                break;
            case 8:
                info->revision = b;
                break;
            case 9:
            case 10:
            case 11:
            case 12:
                info->serial |= (uint32_t) b << ((12 - i) * 8);
                break;
            case 13:
                info->manufacturing_year = b << 4;
                break;
            case 14:
                info->manufacturing_year |= b >> 4;
                info->manufacturing_month = b & 0x0f;
                break;
        }
    }

    /* read csd register */
    uint8_t csd_read_bl_len = 0;
    uint8_t csd_c_size_mult = 0;
    uint16_t csd_c_size = 0;
    if(sd_raw_send_command_r1(CMD_SEND_CSD, 0))
    {
        unselect_card();
        return 0;
    }
    while(sd_raw_rec_byte() != 0xfe);
    for(uint8_t i = 0; i < 18; ++i)
    {
        uint8_t b = sd_raw_rec_byte();

        switch(i)
        {
            case 5:
                csd_read_bl_len = b & 0x0f;
                break;
            case 6:
                csd_c_size = (uint16_t) (b & 0x03) << 8;
                break;
            case 7:
                csd_c_size |= b;
                csd_c_size <<= 2;
                break;
            case 8:
                csd_c_size |= b >> 6;
                ++csd_c_size;
                break;
            case 9:
                csd_c_size_mult = (b & 0x03) << 1;
                break;
            case 10:
                csd_c_size_mult |= b >> 7;

                info->capacity = (uint32_t) csd_c_size << (csd_c_size_mult + csd_read_bl_len + 2);

                break;
            case 14:
                if(b & 0x40)
                    info->flag_copy = 1;
                if(b & 0x20)
                    info->flag_write_protect = 1;
                if(b & 0x10)
                    info->flag_write_protect_temp = 1;
                info->format = (b & 0x0c) >> 2;
                break;
        }
    }

    unselect_card();

    return 1;
}