Takes in a one-hot bit vector (
selector), and outputs the value of the
corresponding input. All selectors and inputs are concatenated into
a single vector each.
If more than one
selector bit is set, the output is a Boolean combination
of the selected input words, as specified by
OPERATION: OR for a plain
multiplexer, AND to show each bit where all the words agree, NOR to show each
bit which are not set in all the words, etc...
IMPLEMENTATION parameter defaults to "AND" since this is all Boolean
logic, though if you are feeding the input words from registers all sharing
common control logic, you might get a possibly better result by selecting
"MUX". If it matters for speed or area, use the implementation which ends
up using the register's reset/clear pin, which will remove the Annuller
logic from the multiplexer itself.
`default_nettype none module Multiplexer_One_Hot #( parameter WORD_WIDTH = 0, parameter WORD_COUNT = 0, parameter OPERATION = "OR", parameter IMPLEMENTATION = "AND", // Do not set at instantiation parameter TOTAL_WIDTH = WORD_COUNT * WORD_WIDTH ) ( input wire [WORD_COUNT-1:0] selectors, input wire [TOTAL_WIDTH-1:0] words_in, output wire [WORD_WIDTH-1:0] word_out );
First, create a copy of
words_in, but with non-selected words annulled.
wire [TOTAL_WIDTH-1:0] words_in_selected; generate genvar i; for (i=0; i < WORD_COUNT; i=i+1) begin : per_word Annuller #( .WORD_WIDTH (WORD_WIDTH), .IMPLEMENTATION (IMPLEMENTATION) ) select_input ( .annul (selectors[i] == 1'b0), .data_in (words_in [WORD_WIDTH*i +: WORD_WIDTH]), .data_out (words_in_selected [WORD_WIDTH*i +: WORD_WIDTH]) ); end endgenerate
Then reduce the filtered words to one word, maybe getting a final useful
computation done in the process, depending on the selected
Word_Reducer #( .OPERATION (OPERATION), .WORD_WIDTH (WORD_WIDTH), .WORD_COUNT (WORD_COUNT) ) combine_words ( .words_in (words_in_selected), .word_out (word_out) ); endmodule
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