HSID Main (hsid_main)

This module integrates the modules described previously and serves as the main IP core of the project. Using input data from the HSPs and reference signatures, it determines which reference signature most closely matches the captured HSP. The different modules are interconnected as shown in the figure below, in which signals are grouped semantically to avoid cluttering the diagram.

The synchronization of internal processes is managed by an FSM implemented in the hsid_main_fsm module. The table and figure below summarizes the function of each FSM state and its the corresponding FSM graph.

State	Description
HM_IDLE	Idle state
HM_CONFIG	Register hsp_bands and hsp_library_size
HM_READ_HSP_CAPTURED	Write the captured HSP into the FIFO
HM_COMPUTE_MSE	Write the reference signature into the FIFO and compute the MSE
HM_WAIT_MSE	Wait until the last MSE computation is complete
HM_COMPARE_MSE	Wait until the last MSE comparison is complete
HM_DONE	Process complete
HM_CLEAR	Cancel the process
HM_ERROR	Configuration error

The internal state of the module is exposed through the block control interface (handshake) via the signals idle, ready, done, cancelled, and error. The table below lists the values of these signals depending on the current FSM state.

State	idle	ready	done	cancelled	error
HM_IDLE	1	0	0	0	0
HM_CONFIG	0	0	0	0	0
HM_READ_HSP_CAPTURED	0	1	0	0	0
HM_COMPUTE_MSE	0	!fifo_ref_full	0	0	0
HM_WAIT_MSE	0	0	0	0	0
HM_COMPARE_MSE	0	0	0	0	0
HM_DONE	0	0	1	0	0
HM_CLEAR	0	0	0	1	0
HM_ERROR	0	0	0	0	1

Assuming there are m reference signatures and each HSP contains n bands, the estimated latency in cycles for this module is given by:

\[ \frac{n}{2} + \frac{nm}{2} + 7 + (K + 1) \]

The constant term 7 accounts for the final operations, which include: reading from the FIFO, subtraction, multiplication, accumulation, accumulator summation, comparison, and assertion of the done signal. The other \(K + 1\) cycles depends on the dimension of the module hsid_divider. The figure below shows an example waveform for an HSP with 10 bands and 2 reference signatures using a 5-bit divider. There is also some description of the final steps in the pipelines.