Witch of Git - nan-gate/blob - techlib.sv

   1 `define POS0 3'b000
   2 `define NEG0 3'b100
   3 `define POS1 3'b001
   4 `define NEG1 3'b101
   5 `define PINF 3'b010
   6 `define NINF 3'b110
   7 `define PNAN 3'b011
   8 `define NNAN 3'b111
   9 `define ANAN 3'b?11
  10 `define ANYF 3'b???
  11
  12 // A NaN gate! Computes `Inf - max(x+y, -Inf)`.
  13 // See http://tom7.org/nand/
  14 module nan_fp3(
  15     input      [2:0] A,
  16     input      [2:0] B,
  17     output reg [2:0] Y
  18 );
  19
  20 always begin
  21     casez ({A, B})
  22     {`ANYF, `ANAN}, {`ANAN, `ANYF}: Y = `PINF;
  23     {`PINF, `NINF}, {`NINF, `PINF}: Y = `PINF;
  24     {`ANYF, `PINF}, {`PINF, `ANYF}: Y = `PNAN;
  25     default: Y = `PINF;
  26     endcase
  27 end
  28 endmodule
  29
  30 // Convert a bit into an fp3
  31 module bit_to_fp3(input A, output [2:0] Y);
  32 assign Y = A ? `PNAN : `PINF;
  33 endmodule
  34
  35 // Convert an fp3 into a bit
  36 module fp3_to_bit(input [2:0] A, output reg Y);
  37 always begin
  38     case (A)
  39     `PNAN, `NNAN: Y = 1'b1;
  40     default: Y = 1'b0;
  41     endcase
  42 end
  43 endmodule
  44