entropy_sha256_whitener

Condition a 32-bit entropy stream with SHA-256 whitening per NIST SP 800-90B.

Accumulates 16 words (512 bits) into a SHA-256 block and streams the 256-bit digest as eight 32-bit words. When enable_i is low the module bypasses hashing and passes entropy through with ready/valid. busy_o, input_count_o, and output_count_o report hasher progress.

Ports

Table 1. Ports
Name	Direction	Type	Description
`clk_i`	input	`logic`	System clock.
`rst_ni`	input	`logic`	Active-low asynchronous reset.
`entropy_valid_i`	input	`logic`	Qualifies entropy_data_i on the input handshake.
`entropy_data_i`	input	`logic [31:0]`	Raw entropy word to hash, or to pass through in bypass.
`entropy_ready_o`	output	`logic`	Input handshake ready; low while hashing or streaming a digest.
`whitened_valid_o`	output	`logic`	Qualifies whitened_data_o on the output handshake.
`whitened_data_o`	output	`logic [31:0]`	Digest word in order from word 0, or the input word in bypass.
`whitened_ready_i`	input	`logic`	Output handshake ready; advances to the next digest word.
`enable_i`	input	`logic`	High hashes the stream; low bypasses hashing and passes entropy_data_i straight through.
`busy_o`	output	`logic`	High while enabled and a digest is being computed or streamed.
`input_count_o`	output	`logic [3:0]`	Words accepted into the current 16-word block.
`output_count_o`	output	`logic [3:0]`	Digest words still to be streamed; zero while enable_i is low.