Name change...

- Calling a random number generator is overstepping..

stdlib/rtl/oh_lfsr.v

@@ -0,0 +1,58 @@
+//#############################################################################
+//# Function: Random number generator                                         #
+//#############################################################################
+//# Author:   Andreas Olofsson                                                #
+//# License:  MIT (see LICENSE file in OH! repository)                        #
+//#############################################################################
+//
+// References:
+// https://users.ece.cmu.edu/~koopman/lfsr/index.html
+//
+//############################################################################
+module oh_random
+  #(parameter N    = 32      //support multiple of 32 for now...
+    )
+   (
+    input 	   clk,
+    input 	   nreset, //async reset
+    input 	   en, // enable counter
+    input [1:0]    mode,// 0=fibonacci,1=galois
+    input 	   lsbfirst,// 1=shift from lsb, 0=shift from msb
+    input [N-1:0]  taps, // taps
+    input [N-1:0]  seed, // seed
+    input [N-1:0]  mask, // mask output (1 = active)
+    output [N-1:0] out  // output value
+    );
+
+   // TODO: support non-multiples of 32
+   reg [N-1:0] 	   lfsr_reg[0:N/32-1];
+   wire [N-1:0]    lfsr_in[0:N/32-1];
+   wire [N-1:0]    taps_sel[0:N/32-1];
+   wire [N/32-1:0] feedback;
+
+   // instantiate multiple 32bit rngs
+   genvar 	   i,j;
+   generate
+      for(i=0;i<(N/32);i=i+1) begin
+	 //taps
+	 assign taps_sel[i] = entaps ? taps[(i+1)*32-1:i*32]: 32'h80000057 << 1;
+	 //lfsr reg
+	 always @(posedge clk or negedge nreset)
+	   if(~nreset)
+	     lfsr_reg[i] <= seed[(i+1)*32-1:i*32];
+	   else if(en)
+	     lfsr_reg[i] <= lfsr_in[i];
+	 // feeback
+	 assign feedback[i]     = lfsr_reg[i][31];
+	 assign lfsr_in[i][0]   = feedback[i];
+	 for(j=1;j<32;j=j+1) begin
+	      assign lfsr_in[i][j] = taps_sel[i][j] ? (lfsr_reg[i][j-1] ^ feedback[i]) :
+				     lfsr_reg[i][j-1];
+
+	 end
+	 assign out[(i+1)*32-1:i*32] = mask[(i+1)*32-1:i*32] & lfsr_reg[i];
+      end // for (i=0;<N/32;i=i+1)
+   endgenerate
+
+
+endmodule // oh_random