Atmel port fail to send retry transmissions

Hi,

I'm porting the DLMS.c to esp32 IDF and I used the Atmel port as base reference.

On the main.c, funtion uart_write, the bytes between data->position and data->size are transmitted.
After the first transmission, data->position is equal to data->size. In case of retry transmissions, it will not transmit because of that.

The data->position should not be changed or should be restored to the original value.