Function rt_msd_read

components/drivers/spi/dev_spi_msd.c:1212–1286

}

static rt_ssize_t rt_msd_read(rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size)
{
    struct msd_device *msd = (struct msd_device *)dev;
    uint8_t response[MSD_RESPONSE_MAX_LEN];
    rt_err_t result = RT_EOK;

    result = MSD_take_owner(msd->spi_device);

    if (result != RT_EOK)
    {
        goto _exit;
    }

    /* SINGLE_BLOCK? */
    if (size == 1)
    {
        rt_spi_take(msd->spi_device);

        result = _send_cmd(msd->spi_device, READ_SINGLE_BLOCK, pos * msd->geometry.bytes_per_sector, 0x00, response_r1, response);
        if ((result != RT_EOK) || (response[0] != MSD_RESPONSE_NO_ERROR))
        {
            MSD_DEBUG("[err] read SINGLE_BLOCK #%d fail!\r\n", pos);
            size = 0;
            goto _exit;
        }

        result = _read_block(msd->spi_device, buffer, msd->geometry.bytes_per_sector);
        if (result != RT_EOK)
        {
            MSD_DEBUG("[err] read SINGLE_BLOCK #%d fail!\r\n", pos);
            size = 0;
        }
    }
    else if (size > 1)
    {
        uint32_t i;

        rt_spi_take(msd->spi_device);

        result = _send_cmd(msd->spi_device, READ_MULTIPLE_BLOCK, pos * msd->geometry.bytes_per_sector, 0x00, response_r1, response);
        if ((result != RT_EOK) || (response[0] != MSD_RESPONSE_NO_ERROR))
        {
            MSD_DEBUG("[err] read READ_MULTIPLE_BLOCK #%d fail!\r\n", pos);
            size = 0;
            goto _exit;
        }

        for (i = 0; i < size; i++)
        {
            result = _read_block(msd->spi_device,
                                 (uint8_t *)buffer + msd->geometry.bytes_per_sector * i,
                                 msd->geometry.bytes_per_sector);
            if (result != RT_EOK)
            {
                MSD_DEBUG("[err] read READ_MULTIPLE_BLOCK #%d fail!\r\n", pos);
                size = i;
                break;
            }