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// a simple test case extracted from systemcaes (as included in iwls2005)
// this design has latches (or logic loops) for the two temp variables.
// this latches (or logic loops) must be removed in the final synthesis results
module aes(
// inputs
input [3:0] addroundkey_data_i,
input [3:0] addroundkey_data_reg,
input [3:0] addroundkey_round,
input [3:0] key_i,
input [3:0] keysched_new_key_o,
input [3:0] round,
input addroundkey_start_i,
input keysched_ready_o,
// outputs
output reg [3:0] keysched_last_key_i,
output reg [3:0] keysched_round_i,
output reg [3:0] next_addroundkey_data_reg,
output reg [3:0] next_addroundkey_round,
output reg [3:0] round_data_var,
output reg keysched_start_i,
output reg next_addroundkey_ready_o
);
// temp variables
reg [3:0] data_var;
reg [3:0] round_key_var;
always @*
begin
keysched_start_i = 0;
keysched_round_i = addroundkey_round;
round_data_var = addroundkey_data_reg;
next_addroundkey_data_reg = addroundkey_data_reg;
next_addroundkey_ready_o = 0;
next_addroundkey_round = addroundkey_round;
if (addroundkey_round == 1 || addroundkey_round == 0)
keysched_last_key_i = key_i;
else
keysched_last_key_i = keysched_new_key_o;
if (round == 0 && addroundkey_start_i)
begin
data_var = addroundkey_data_i;
round_key_var = key_i;
round_data_var = round_key_var ^ data_var;
next_addroundkey_data_reg = round_data_var;
next_addroundkey_ready_o = 1;
end
else if (addroundkey_start_i && round != 0)
begin
keysched_last_key_i = key_i;
keysched_start_i = 1;
keysched_round_i = 1;
next_addroundkey_round = 1;
end
else if (addroundkey_round != round && keysched_ready_o)
begin
next_addroundkey_round = addroundkey_round + 1;
keysched_last_key_i = keysched_new_key_o;
keysched_start_i = 1;
keysched_round_i = addroundkey_round + 1;
end
else if (addroundkey_round == round && keysched_ready_o)
begin
data_var = addroundkey_data_i;
round_key_var = keysched_new_key_o;
round_data_var = round_key_var ^ data_var;
next_addroundkey_data_reg = round_data_var;
next_addroundkey_ready_o = 1;
next_addroundkey_round = 0;
end
end
endmodule
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