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New random number generator (wip)

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aolofsson 2022-06-27 09:28:06 -04:00
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commit 5076694f60
1 changed files with 33 additions and 29 deletions
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stdlib/rtl/oh_random.v
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@ -1,49 +1,53 @@
//############################################################################# //#############################################################################
//# Function: Random number generator //# Function: Random number generator #
//############################################################################# //#############################################################################
//# Author: Andreas Olofsson # //# Author: Andreas Olofsson #
//# License: MIT (see LICENSE file in OH! repository) # //# License: MIT (see LICENSE file in OH! repository) #
//############################################################################# //#############################################################################
module oh_random module oh_random
#(parameter N = 32, //width of counter (max value) #(parameter N = 32 //support multiple of 32 for now...
parameter SEED = 32'haaaaaaaa //non zero number to start with
) )
( (
input clk, input clk,
input nreset, //async reset input nreset, //async reset
input [N-1:0] mask, //mask output (1 = active) input en, // enable counter
input en, //enable counter input entaps, // enable taps input
input [N-1:0] taps, // user driven taps
input [N-1:0] seed, // seed
input [N-1:0] mask, // mask output (1 = active)
output [N-1:0] out //random output pulse output [N-1:0] out //random output pulse
); );
wire [N-1:0] taps_sel; // TODO: support non-multiples of 32
reg [N-1:0] lfsr_reg; reg [N-1:0] lfsr_reg[0:N/32-1];
wire [N-1:0] lfsr_in; 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;
// LFSR tap selector (TODO: complete table) // instantiate multiple 32bit rngs
genvar i,j;
generate generate
case(N) for(i=0;i<(N/32);i=i+1) begin
32: assign taps_sel[31:0] = 32'h80000057<<1; //taps
endcase // case (N) 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 endgenerate
// counter
always @(posedge clk or negedge nreset)
if(~nreset)
lfsr_reg[N-1:0] <= SEED;
else if(en)
lfsr_reg[N-1:0] <= lfsr_in[N-1:0];
assign feedback = lfsr_reg[N-1]; //feedback from MSB
assign lfsr_in[0] = feedback; //unconditional feedback for [0]
genvar i;
for(i=1;i<N;i=i+1)
assign lfsr_in[i] = taps_sel[i] ? (lfsr_reg[i-1] ^ feedback) :
lfsr_reg[i-1];
assign out[N-1:0] = mask[N-1:0] & lfsr_reg[N-1:0];
endmodule // oh_random endmodule // oh_random