Burst length attribute
This attribute specifies the number of data transfers that occur within this burst.
It must have a value between 1 and 256 for defined-length burst. Additional restrictions apply depending on the value of the burst type attribute.
The method set_length() must set this attribute to the value passed as argument. The method get_length() must return the value of this attribute.
The default value of this attribute must be 1, for single transfer.
This attribute is specific to the AXI, ACE, and AHB buses. It is ignored for transactions modeling transfers on the APB bus.
The maximum burst length value for AXI3 and AHB buses is 16, and the maximum value for AXI4 and ACE buses is 256.