One of my thoughts was to use an even-odd approach. This is typically done when using GPUs in a sequential fashion. I decided to do this pipelined. This approach turned out to be extremely inefficient in retrospect. In a future post, I’ll do a state machine based approach which will be good for area and power conscious designs.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 | module compare # ( parameter DWIDTH = 32 ) ( input clk, input [DWIDTH-1:0] a_in, input [DWIDTH-1:0] b_in, input [DWIDTH-1:0] c_in, input [DWIDTH-1:0] d_in, output logic [DWIDTH-1:0] a_out, output logic [DWIDTH-1:0] b_out, output logic [DWIDTH-1:0] c_out, output logic [DWIDTH-1:0] d_out ); logic [DWIDTH-1:0] a_reg; logic [DWIDTH-1:0] b_reg; logic [DWIDTH-1:0] c_reg; logic [DWIDTH-1:0] d_reg; logic [DWIDTH-1:0] a_odd; logic [DWIDTH-1:0] b_odd; logic [DWIDTH-1:0] c_odd; logic [DWIDTH-1:0] d_odd; logic [DWIDTH-1:0] a_even; logic [DWIDTH-1:0] b_even; logic [DWIDTH-1:0] c_even; logic [DWIDTH-1:0] d_even; logic [DWIDTH-1:0] a_odd1; logic [DWIDTH-1:0] b_odd1; logic [DWIDTH-1:0] c_odd1; logic [DWIDTH-1:0] d_odd1; always_ff @(posedge clk) begin a_reg <= a_in; b_reg <= b_in; c_reg <= c_in; d_reg <= d_in; // First stage, compare odds a_odd <= (a_reg < b_reg) ? a_reg : b_reg; b_odd <= (a_reg < b_reg) ? b_reg : a_reg; c_odd <= (c_reg < d_reg) ? c_reg : d_reg; d_odd <= (c_reg < d_reg) ? d_reg : c_reg; // Sort evens a_even <= a_odd; b_even <= (b_odd < c_odd) ? b_odd : c_odd; c_even <= (b_odd < c_odd) ? c_odd : b_odd; d_even <= d_odd; // Sort odds again - we are now guaranteed to be sorted a_odd1 <= (a_even < b_even) ? a_even : b_even; b_odd1 <= (a_even < b_even) ? b_even : a_even; c_odd1 <= (c_even < d_even) ? c_even : d_even; d_odd1 <= (c_even < d_even) ? d_even : c_even; a_out <= a_odd1; b_out <= (b_odd1 < c_odd1) ? b_odd1 : c_odd1; c_out <= (b_odd1 < c_odd1) ? c_odd1 : b_odd1; d_out <= d_odd1; end endmodule |

Fmax: > 800 Mhz

LUT: 410

FF: 640