hw/ip/csrng/rtl/csrng_ctr_drbg_cmd.sv - 3p/lowrisc/opentitan - Git at Google

 // Copyright lowRISC contributors.
 // Licensed under the Apache License, Version 2.0, see LICENSE for details.
 // SPDX-License-Identifier: Apache-2.0
 //
 // Description: csrng ctr_drbg commands module
 //
 // Accepts all csrng commands

 module csrng_ctr_drbg_cmd import csrng_pkg::*; #(
   parameter int Cmd = 3,
   parameter int StateId = 4,
   parameter int BlkLen = 128,
   parameter int KeyLen = 256,
   parameter int SeedLen = 384,
   parameter int CtrLen  = 32
 ) (
   input logic                clk_i,
   input logic                rst_ni,

    // command interface
   input logic                ctr_drbg_cmd_enable_i,
   input logic                ctr_drbg_cmd_req_i,
   output logic               ctr_drbg_cmd_rdy_o, // ready to process the req above
   input logic [Cmd-1:0]      ctr_drbg_cmd_ccmd_i,    // current command
   input logic [StateId-1:0]  ctr_drbg_cmd_inst_id_i, // instantance id
   input logic                ctr_drbg_cmd_glast_i,   // gen cmd last beat
   input logic [SeedLen-1:0]  ctr_drbg_cmd_entropy_i, // es entropy
   input logic                ctr_drbg_cmd_entropy_fips_i, // es entropy)fips
   input logic [SeedLen-1:0]  ctr_drbg_cmd_adata_i,   // additional data
   input logic [KeyLen-1:0]   ctr_drbg_cmd_key_i,
   input logic [BlkLen-1:0]   ctr_drbg_cmd_v_i,
   input logic [CtrLen-1:0]   ctr_drbg_cmd_rc_i,
   input logic                ctr_drbg_cmd_fips_i,

   output logic               ctr_drbg_cmd_ack_o, // final ack when update process has been completed
   output logic               ctr_drbg_cmd_sts_o, // final ack status
   input logic                ctr_drbg_cmd_rdy_i, // ready to process the ack above
   output logic [Cmd-1:0]     ctr_drbg_cmd_ccmd_o,
   output logic [StateId-1:0] ctr_drbg_cmd_inst_id_o,
   output logic               ctr_drbg_cmd_glast_o,
   output logic               ctr_drbg_cmd_fips_o,
   output logic [SeedLen-1:0] ctr_drbg_cmd_adata_o,
   output logic [KeyLen-1:0]  ctr_drbg_cmd_key_o,
   output logic [BlkLen-1:0]  ctr_drbg_cmd_v_o,
   output logic [CtrLen-1:0]  ctr_drbg_cmd_rc_o,

    // update interface
   output logic               cmd_upd_req_o,
   input logic                upd_cmd_rdy_i,
   output logic [Cmd-1:0]     cmd_upd_ccmd_o,
   output logic [StateId-1:0] cmd_upd_inst_id_o,
   output logic [SeedLen-1:0] cmd_upd_pdata_o,
   output logic [KeyLen-1:0]  cmd_upd_key_o,
   output logic [BlkLen-1:0]  cmd_upd_v_o,

   input logic                upd_cmd_ack_i,
   output logic               cmd_upd_rdy_o,
   input logic [Cmd-1:0]      upd_cmd_ccmd_i,
   input logic [StateId-1:0]  upd_cmd_inst_id_i,
   input logic [KeyLen-1:0]   upd_cmd_key_i,
   input logic [BlkLen-1:0]   upd_cmd_v_i,
   // misc
   output logic [2:0]         ctr_drbg_cmd_sfifo_cmdreq_err_o,
   output logic [2:0]         ctr_drbg_cmd_sfifo_rcstage_err_o,
   output logic [2:0]         ctr_drbg_cmd_sfifo_keyvrc_err_o
 );

   localparam int CmdreqFifoDepth = 1;
   localparam int CmdreqFifoWidth = KeyLen+BlkLen+CtrLen+1+2*SeedLen+1+StateId+Cmd;
   localparam int RCStageFifoDepth = 1;
   localparam int RCStageFifoWidth = KeyLen+BlkLen+StateId+CtrLen+1+SeedLen+1+Cmd;
   localparam int KeyVRCFifoDepth = 1;
   localparam int KeyVRCFifoWidth = KeyLen+BlkLen+CtrLen+1+SeedLen+1+StateId+Cmd;


   // signals
   logic [Cmd-1:0]     cmdreq_ccmd;
   logic [StateId-1:0] cmdreq_id;
   logic               cmdreq_glast;
   logic [SeedLen-1:0] cmdreq_entropy;
   logic               cmdreq_entropy_fips;
   logic [SeedLen-1:0] cmdreq_adata;
   logic [KeyLen-1:0]  cmdreq_key;
   logic [BlkLen-1:0]  cmdreq_v;
   logic [CtrLen-1:0]  cmdreq_rc;

   logic [SeedLen-1:0] prep_seed_material;
   logic [KeyLen-1:0]  prep_key;
   logic [BlkLen-1:0]  prep_v;
   logic [CtrLen-1:0]  prep_rc;
   logic               prep_gen_adata_null;
   logic [KeyLen-1:0]  rcstage_key;
   logic [BlkLen-1:0]  rcstage_v;
   logic [StateId-1:0] rcstage_id;
   logic [CtrLen-1:0]  rcstage_rc;
   logic [Cmd-1:0]     rcstage_ccmd;
   logic               rcstage_glast;
   logic [SeedLen-1:0] rcstage_adata;
   logic               rcstage_fips;
   logic               fips_modified;

   // cmdreq fifo
   logic [CmdreqFifoWidth-1:0] sfifo_cmdreq_rdata;
   logic                       sfifo_cmdreq_push;
   logic [CmdreqFifoWidth-1:0] sfifo_cmdreq_wdata;
   logic                       sfifo_cmdreq_pop;
   logic                       sfifo_cmdreq_full;
   logic                       sfifo_cmdreq_not_empty;

   // rcstage fifo
   logic [RCStageFifoWidth-1:0] sfifo_rcstage_rdata;
   logic                        sfifo_rcstage_push;
   logic [RCStageFifoWidth-1:0] sfifo_rcstage_wdata;
   logic                        sfifo_rcstage_pop;
   logic                        sfifo_rcstage_full;
   logic                        sfifo_rcstage_not_empty;

   // keyvrc fifo
   logic [KeyVRCFifoWidth-1:0]  sfifo_keyvrc_rdata;
   logic                        sfifo_keyvrc_push;
   logic [KeyVRCFifoWidth-1:0]  sfifo_keyvrc_wdata;
   logic                        sfifo_keyvrc_pop;
   logic                        sfifo_keyvrc_full;
   logic                        sfifo_keyvrc_not_empty;

   // flops
   logic                        gen_adata_null_q, gen_adata_null_d;

   always_ff @(posedge clk_i or negedge rst_ni) begin
     if (!rst_ni) begin
       gen_adata_null_q  <= '0;
     end else begin
       gen_adata_null_q  <= gen_adata_null_d;
     end
   end

   //--------------------------------------------
   // input request fifo for staging cmd request
   //--------------------------------------------

   prim_fifo_sync #(
     .Width(CmdreqFifoWidth),
     .Pass(0),
     .Depth(CmdreqFifoDepth),
     .OutputZeroIfEmpty(1'b0)
   ) u_prim_fifo_sync_cmdreq (
     .clk_i          (clk_i),
     .rst_ni         (rst_ni),
     .clr_i          (!ctr_drbg_cmd_enable_i),
     .wvalid_i       (sfifo_cmdreq_push),
     .wready_o       (),
     .wdata_i        (sfifo_cmdreq_wdata),
     .rvalid_o       (sfifo_cmdreq_not_empty),
     .rready_i       (sfifo_cmdreq_pop),
     .rdata_o        (sfifo_cmdreq_rdata),
     .full_o         (sfifo_cmdreq_full),
     .depth_o        (),
     .err_o          ()
   );

   assign fips_modified = ((ctr_drbg_cmd_ccmd_i == INS) ||
                           (ctr_drbg_cmd_ccmd_i == RES)) ? ctr_drbg_cmd_entropy_fips_i :
                          ctr_drbg_cmd_fips_i;

   assign sfifo_cmdreq_wdata = {ctr_drbg_cmd_key_i,ctr_drbg_cmd_v_i,
                                ctr_drbg_cmd_rc_i,fips_modified,
                                ctr_drbg_cmd_entropy_i,ctr_drbg_cmd_adata_i,
                                ctr_drbg_cmd_glast_i,
                                ctr_drbg_cmd_inst_id_i,ctr_drbg_cmd_ccmd_i};

   assign sfifo_cmdreq_push = ctr_drbg_cmd_enable_i && ctr_drbg_cmd_req_i;

   assign sfifo_cmdreq_pop = ctr_drbg_cmd_enable_i &&
          (upd_cmd_rdy_i || gen_adata_null_q) && sfifo_cmdreq_not_empty;

   assign {cmdreq_key,cmdreq_v,cmdreq_rc,
           cmdreq_entropy_fips,cmdreq_entropy,cmdreq_adata,
           cmdreq_glast,cmdreq_id,cmdreq_ccmd} = sfifo_cmdreq_rdata;

   assign ctr_drbg_cmd_rdy_o = !sfifo_cmdreq_full;

   assign ctr_drbg_cmd_sfifo_cmdreq_err_o =
          {(sfifo_cmdreq_push && sfifo_cmdreq_full),
           (sfifo_cmdreq_pop && !sfifo_cmdreq_not_empty),
           (sfifo_cmdreq_full && !sfifo_cmdreq_not_empty)};


   //--------------------------------------------
   // prepare values for update step
   //--------------------------------------------

   assign prep_seed_material =
          (cmdreq_ccmd == INS) ? (cmdreq_entropy ^ cmdreq_adata) :
          (cmdreq_ccmd == RES) ? (cmdreq_entropy ^ cmdreq_adata) :
          (cmdreq_ccmd == GEN) ? cmdreq_adata :
          (cmdreq_ccmd == UPD) ? cmdreq_adata :
          '0;

   assign prep_key =
          (cmdreq_ccmd == INS) ? {KeyLen{1'b0}} :
          (cmdreq_ccmd == RES) ? cmdreq_key :
          (cmdreq_ccmd == GEN) ? cmdreq_key :
          (cmdreq_ccmd == UPD) ? cmdreq_key :
          '0;

   assign prep_v =
          (cmdreq_ccmd == INS) ? {BlkLen{1'b0}} :
          (cmdreq_ccmd == RES) ? cmdreq_v :
          (cmdreq_ccmd == GEN) ? cmdreq_v :
          (cmdreq_ccmd == UPD) ? cmdreq_v :
          '0;

   assign prep_rc =
          (cmdreq_ccmd == INS) ? {{(CtrLen-1){1'b0}},1'b1} :
          (cmdreq_ccmd == RES) ? {{(CtrLen-1){1'b0}},1'b1} :
          (cmdreq_ccmd == GEN) ? cmdreq_rc :
          (cmdreq_ccmd == UPD) ? cmdreq_rc :
          '0;

   assign prep_gen_adata_null = (cmdreq_ccmd == GEN) && (cmdreq_adata == '0);

   assign gen_adata_null_d = prep_gen_adata_null;

   // send to the update block
   assign cmd_upd_req_o = sfifo_cmdreq_not_empty && !prep_gen_adata_null;
   assign cmd_upd_ccmd_o = cmdreq_ccmd;
   assign cmd_upd_inst_id_o = cmdreq_id;
   assign cmd_upd_pdata_o = prep_seed_material;
   assign cmd_upd_key_o = prep_key;
   assign cmd_upd_v_o = prep_v;


   //--------------------------------------------
   // fifo to stage rc and command, waiting for update block to ack
   //--------------------------------------------

   prim_fifo_sync #(
     .Width(RCStageFifoWidth),
     .Pass(0),
     .Depth(RCStageFifoDepth),
     .OutputZeroIfEmpty(1'b0)
   ) u_prim_fifo_sync_rcstage (
     .clk_i          (clk_i),
     .rst_ni         (rst_ni),
     .clr_i          (!ctr_drbg_cmd_enable_i),
     .wvalid_i       (sfifo_rcstage_push),
     .wready_o       (),
     .wdata_i        (sfifo_rcstage_wdata),
     .rvalid_o       (sfifo_rcstage_not_empty),
     .rready_i       (sfifo_rcstage_pop),
     .rdata_o        (sfifo_rcstage_rdata),
     .full_o         (sfifo_rcstage_full),
     .depth_o        (),
     .err_o          ()
   );

   assign sfifo_rcstage_push = sfifo_cmdreq_pop;
   assign sfifo_rcstage_wdata = {prep_key,prep_v,cmdreq_id,prep_rc,cmdreq_entropy_fips,
                                 cmdreq_adata,cmdreq_glast,cmdreq_ccmd};
   assign sfifo_rcstage_pop = sfifo_rcstage_not_empty && (upd_cmd_ack_i || gen_adata_null_q);
   assign {rcstage_key,rcstage_v,rcstage_id,rcstage_rc,rcstage_fips,
           rcstage_adata,rcstage_glast,rcstage_ccmd} = sfifo_rcstage_rdata;


   assign ctr_drbg_cmd_sfifo_rcstage_err_o =
          {(sfifo_rcstage_push && sfifo_rcstage_full),
           (sfifo_rcstage_pop && !sfifo_rcstage_not_empty),
           (sfifo_rcstage_full && !sfifo_rcstage_not_empty)};

   assign cmd_upd_rdy_o = sfifo_rcstage_not_empty && !sfifo_keyvrc_full;

   //--------------------------------------------
   // final cmd block processing
   //--------------------------------------------

   prim_fifo_sync #(
     .Width(KeyVRCFifoWidth),
     .Pass(0),
     .Depth(KeyVRCFifoDepth),
     .OutputZeroIfEmpty(1'b0)
   ) u_prim_fifo_sync_keyvrc (
     .clk_i          (clk_i),
     .rst_ni         (rst_ni),
     .clr_i          (!ctr_drbg_cmd_enable_i),
     .wvalid_i       (sfifo_keyvrc_push),
     .wready_o       (),
     .wdata_i        (sfifo_keyvrc_wdata),
     .rvalid_o       (sfifo_keyvrc_not_empty),
     .rready_i       (sfifo_keyvrc_pop),
     .rdata_o        (sfifo_keyvrc_rdata),
     .full_o         (sfifo_keyvrc_full),
     .depth_o        (),
     .err_o          ()
   );

   assign sfifo_keyvrc_push = sfifo_rcstage_pop;

   // if a UNI command, reset the state values
   assign sfifo_keyvrc_wdata = (rcstage_ccmd == UNI) ?
          {{(KeyLen+BlkLen+CtrLen+1+SeedLen){1'b0}},rcstage_glast,upd_cmd_inst_id_i,upd_cmd_ccmd_i} :
          gen_adata_null_q ?
          {rcstage_key,rcstage_v,rcstage_rc,rcstage_fips,
           rcstage_adata,rcstage_glast,rcstage_id,rcstage_ccmd} :
          {upd_cmd_key_i,upd_cmd_v_i,rcstage_rc,rcstage_fips,
           rcstage_adata,rcstage_glast,upd_cmd_inst_id_i,upd_cmd_ccmd_i};

   assign sfifo_keyvrc_pop = ctr_drbg_cmd_rdy_i && sfifo_keyvrc_not_empty;
   assign {ctr_drbg_cmd_key_o,ctr_drbg_cmd_v_o,ctr_drbg_cmd_rc_o,
           ctr_drbg_cmd_fips_o,ctr_drbg_cmd_adata_o,ctr_drbg_cmd_glast_o,
           ctr_drbg_cmd_inst_id_o,ctr_drbg_cmd_ccmd_o} = sfifo_keyvrc_rdata;

   assign ctr_drbg_cmd_sfifo_keyvrc_err_o =
          {(sfifo_keyvrc_push && sfifo_keyvrc_full),
           (sfifo_keyvrc_pop && !sfifo_keyvrc_not_empty),
           (sfifo_keyvrc_full && !sfifo_keyvrc_not_empty)};

   // block ack
   assign ctr_drbg_cmd_ack_o = sfifo_keyvrc_pop;

   assign ctr_drbg_cmd_sts_o = sfifo_keyvrc_pop && (ctr_drbg_cmd_ccmd_o == UNI) &&
          ((KeyLen == '0) && (BlkLen == '0) && (CtrLen == '0));


 endmodule
	// Copyright lowRISC contributors.
	// Licensed under the Apache License, Version 2.0, see LICENSE for details.
	// SPDX-License-Identifier: Apache-2.0
	//
	// Description: csrng ctr_drbg commands module
	//
	// Accepts all csrng commands

	module csrng_ctr_drbg_cmd import csrng_pkg::*; #(
	parameter int Cmd = 3,
	parameter int StateId = 4,
	parameter int BlkLen = 128,
	parameter int KeyLen = 256,
	parameter int SeedLen = 384,
	parameter int CtrLen = 32
	) (
	input logic clk_i,
	input logic rst_ni,

	// command interface
	input logic ctr_drbg_cmd_enable_i,
	input logic ctr_drbg_cmd_req_i,
	output logic ctr_drbg_cmd_rdy_o, // ready to process the req above
	input logic [Cmd-1:0] ctr_drbg_cmd_ccmd_i, // current command
	input logic [StateId-1:0] ctr_drbg_cmd_inst_id_i, // instantance id
	input logic ctr_drbg_cmd_glast_i, // gen cmd last beat
	input logic [SeedLen-1:0] ctr_drbg_cmd_entropy_i, // es entropy
	input logic ctr_drbg_cmd_entropy_fips_i, // es entropy)fips
	input logic [SeedLen-1:0] ctr_drbg_cmd_adata_i, // additional data
	input logic [KeyLen-1:0] ctr_drbg_cmd_key_i,
	input logic [BlkLen-1:0] ctr_drbg_cmd_v_i,
	input logic [CtrLen-1:0] ctr_drbg_cmd_rc_i,
	input logic ctr_drbg_cmd_fips_i,

	output logic ctr_drbg_cmd_ack_o, // final ack when update process has been completed
	output logic ctr_drbg_cmd_sts_o, // final ack status
	input logic ctr_drbg_cmd_rdy_i, // ready to process the ack above
	output logic [Cmd-1:0] ctr_drbg_cmd_ccmd_o,
	output logic [StateId-1:0] ctr_drbg_cmd_inst_id_o,
	output logic ctr_drbg_cmd_glast_o,
	output logic ctr_drbg_cmd_fips_o,
	output logic [SeedLen-1:0] ctr_drbg_cmd_adata_o,
	output logic [KeyLen-1:0] ctr_drbg_cmd_key_o,
	output logic [BlkLen-1:0] ctr_drbg_cmd_v_o,
	output logic [CtrLen-1:0] ctr_drbg_cmd_rc_o,

	// update interface
	output logic cmd_upd_req_o,
	input logic upd_cmd_rdy_i,
	output logic [Cmd-1:0] cmd_upd_ccmd_o,
	output logic [StateId-1:0] cmd_upd_inst_id_o,
	output logic [SeedLen-1:0] cmd_upd_pdata_o,
	output logic [KeyLen-1:0] cmd_upd_key_o,
	output logic [BlkLen-1:0] cmd_upd_v_o,

	input logic upd_cmd_ack_i,
	output logic cmd_upd_rdy_o,
	input logic [Cmd-1:0] upd_cmd_ccmd_i,
	input logic [StateId-1:0] upd_cmd_inst_id_i,
	input logic [KeyLen-1:0] upd_cmd_key_i,
	input logic [BlkLen-1:0] upd_cmd_v_i,
	// misc
	output logic [2:0] ctr_drbg_cmd_sfifo_cmdreq_err_o,
	output logic [2:0] ctr_drbg_cmd_sfifo_rcstage_err_o,
	output logic [2:0] ctr_drbg_cmd_sfifo_keyvrc_err_o
	);

	localparam int CmdreqFifoDepth = 1;
	localparam int CmdreqFifoWidth = KeyLen+BlkLen+CtrLen+1+2*SeedLen+1+StateId+Cmd;
	localparam int RCStageFifoDepth = 1;
	localparam int RCStageFifoWidth = KeyLen+BlkLen+StateId+CtrLen+1+SeedLen+1+Cmd;
	localparam int KeyVRCFifoDepth = 1;
	localparam int KeyVRCFifoWidth = KeyLen+BlkLen+CtrLen+1+SeedLen+1+StateId+Cmd;


	// signals
	logic [Cmd-1:0] cmdreq_ccmd;
	logic [StateId-1:0] cmdreq_id;
	logic cmdreq_glast;
	logic [SeedLen-1:0] cmdreq_entropy;
	logic cmdreq_entropy_fips;
	logic [SeedLen-1:0] cmdreq_adata;
	logic [KeyLen-1:0] cmdreq_key;
	logic [BlkLen-1:0] cmdreq_v;
	logic [CtrLen-1:0] cmdreq_rc;

	logic [SeedLen-1:0] prep_seed_material;
	logic [KeyLen-1:0] prep_key;
	logic [BlkLen-1:0] prep_v;
	logic [CtrLen-1:0] prep_rc;
	logic prep_gen_adata_null;
	logic [KeyLen-1:0] rcstage_key;
	logic [BlkLen-1:0] rcstage_v;
	logic [StateId-1:0] rcstage_id;
	logic [CtrLen-1:0] rcstage_rc;
	logic [Cmd-1:0] rcstage_ccmd;
	logic rcstage_glast;
	logic [SeedLen-1:0] rcstage_adata;
	logic rcstage_fips;
	logic fips_modified;

	// cmdreq fifo
	logic [CmdreqFifoWidth-1:0] sfifo_cmdreq_rdata;
	logic sfifo_cmdreq_push;
	logic [CmdreqFifoWidth-1:0] sfifo_cmdreq_wdata;
	logic sfifo_cmdreq_pop;
	logic sfifo_cmdreq_full;
	logic sfifo_cmdreq_not_empty;

	// rcstage fifo
	logic [RCStageFifoWidth-1:0] sfifo_rcstage_rdata;
	logic sfifo_rcstage_push;
	logic [RCStageFifoWidth-1:0] sfifo_rcstage_wdata;
	logic sfifo_rcstage_pop;
	logic sfifo_rcstage_full;
	logic sfifo_rcstage_not_empty;

	// keyvrc fifo
	logic [KeyVRCFifoWidth-1:0] sfifo_keyvrc_rdata;
	logic sfifo_keyvrc_push;
	logic [KeyVRCFifoWidth-1:0] sfifo_keyvrc_wdata;
	logic sfifo_keyvrc_pop;
	logic sfifo_keyvrc_full;
	logic sfifo_keyvrc_not_empty;

	// flops
	logic gen_adata_null_q, gen_adata_null_d;

	always_ff @(posedge clk_i or negedge rst_ni) begin
	if (!rst_ni) begin
	gen_adata_null_q <= '0;
	end else begin
	gen_adata_null_q <= gen_adata_null_d;
	end
	end

	//--------------------------------------------
	// input request fifo for staging cmd request
	//--------------------------------------------

	prim_fifo_sync #(
	.Width(CmdreqFifoWidth),
	.Pass(0),
	.Depth(CmdreqFifoDepth),
	.OutputZeroIfEmpty(1'b0)
	) u_prim_fifo_sync_cmdreq (
	.clk_i (clk_i),
	.rst_ni (rst_ni),
	.clr_i (!ctr_drbg_cmd_enable_i),
	.wvalid_i (sfifo_cmdreq_push),
	.wready_o (),
	.wdata_i (sfifo_cmdreq_wdata),
	.rvalid_o (sfifo_cmdreq_not_empty),
	.rready_i (sfifo_cmdreq_pop),
	.rdata_o (sfifo_cmdreq_rdata),
	.full_o (sfifo_cmdreq_full),
	.depth_o (),
	.err_o ()
	);

	assign fips_modified = ((ctr_drbg_cmd_ccmd_i == INS) \|\|
	(ctr_drbg_cmd_ccmd_i == RES)) ? ctr_drbg_cmd_entropy_fips_i :
	ctr_drbg_cmd_fips_i;

	assign sfifo_cmdreq_wdata = {ctr_drbg_cmd_key_i,ctr_drbg_cmd_v_i,
	ctr_drbg_cmd_rc_i,fips_modified,
	ctr_drbg_cmd_entropy_i,ctr_drbg_cmd_adata_i,
	ctr_drbg_cmd_glast_i,
	ctr_drbg_cmd_inst_id_i,ctr_drbg_cmd_ccmd_i};

	assign sfifo_cmdreq_push = ctr_drbg_cmd_enable_i && ctr_drbg_cmd_req_i;

	assign sfifo_cmdreq_pop = ctr_drbg_cmd_enable_i &&
	(upd_cmd_rdy_i \|\| gen_adata_null_q) && sfifo_cmdreq_not_empty;

	assign {cmdreq_key,cmdreq_v,cmdreq_rc,
	cmdreq_entropy_fips,cmdreq_entropy,cmdreq_adata,
	cmdreq_glast,cmdreq_id,cmdreq_ccmd} = sfifo_cmdreq_rdata;

	assign ctr_drbg_cmd_rdy_o = !sfifo_cmdreq_full;

	assign ctr_drbg_cmd_sfifo_cmdreq_err_o =
	{(sfifo_cmdreq_push && sfifo_cmdreq_full),
	(sfifo_cmdreq_pop && !sfifo_cmdreq_not_empty),
	(sfifo_cmdreq_full && !sfifo_cmdreq_not_empty)};


	//--------------------------------------------
	// prepare values for update step
	//--------------------------------------------

	assign prep_seed_material =
	(cmdreq_ccmd == INS) ? (cmdreq_entropy ^ cmdreq_adata) :
	(cmdreq_ccmd == RES) ? (cmdreq_entropy ^ cmdreq_adata) :
	(cmdreq_ccmd == GEN) ? cmdreq_adata :
	(cmdreq_ccmd == UPD) ? cmdreq_adata :
	'0;

	assign prep_key =
	(cmdreq_ccmd == INS) ? {KeyLen{1'b0}} :
	(cmdreq_ccmd == RES) ? cmdreq_key :
	(cmdreq_ccmd == GEN) ? cmdreq_key :
	(cmdreq_ccmd == UPD) ? cmdreq_key :
	'0;

	assign prep_v =
	(cmdreq_ccmd == INS) ? {BlkLen{1'b0}} :
	(cmdreq_ccmd == RES) ? cmdreq_v :
	(cmdreq_ccmd == GEN) ? cmdreq_v :
	(cmdreq_ccmd == UPD) ? cmdreq_v :
	'0;

	assign prep_rc =
	(cmdreq_ccmd == INS) ? {{(CtrLen-1){1'b0}},1'b1} :
	(cmdreq_ccmd == RES) ? {{(CtrLen-1){1'b0}},1'b1} :
	(cmdreq_ccmd == GEN) ? cmdreq_rc :
	(cmdreq_ccmd == UPD) ? cmdreq_rc :
	'0;

	assign prep_gen_adata_null = (cmdreq_ccmd == GEN) && (cmdreq_adata == '0);

	assign gen_adata_null_d = prep_gen_adata_null;

	// send to the update block
	assign cmd_upd_req_o = sfifo_cmdreq_not_empty && !prep_gen_adata_null;
	assign cmd_upd_ccmd_o = cmdreq_ccmd;
	assign cmd_upd_inst_id_o = cmdreq_id;
	assign cmd_upd_pdata_o = prep_seed_material;
	assign cmd_upd_key_o = prep_key;
	assign cmd_upd_v_o = prep_v;



	//--------------------------------------------
	// fifo to stage rc and command, waiting for update block to ack
	//--------------------------------------------

	prim_fifo_sync #(
	.Width(RCStageFifoWidth),
	.Pass(0),
	.Depth(RCStageFifoDepth),
	.OutputZeroIfEmpty(1'b0)
	) u_prim_fifo_sync_rcstage (
	.clk_i (clk_i),
	.rst_ni (rst_ni),
	.clr_i (!ctr_drbg_cmd_enable_i),
	.wvalid_i (sfifo_rcstage_push),
	.wready_o (),
	.wdata_i (sfifo_rcstage_wdata),
	.rvalid_o (sfifo_rcstage_not_empty),
	.rready_i (sfifo_rcstage_pop),
	.rdata_o (sfifo_rcstage_rdata),
	.full_o (sfifo_rcstage_full),
	.depth_o (),
	.err_o ()
	);

	assign sfifo_rcstage_push = sfifo_cmdreq_pop;
	assign sfifo_rcstage_wdata = {prep_key,prep_v,cmdreq_id,prep_rc,cmdreq_entropy_fips,
	cmdreq_adata,cmdreq_glast,cmdreq_ccmd};
	assign sfifo_rcstage_pop = sfifo_rcstage_not_empty && (upd_cmd_ack_i \|\| gen_adata_null_q);
	assign {rcstage_key,rcstage_v,rcstage_id,rcstage_rc,rcstage_fips,
	rcstage_adata,rcstage_glast,rcstage_ccmd} = sfifo_rcstage_rdata;


	assign ctr_drbg_cmd_sfifo_rcstage_err_o =
	{(sfifo_rcstage_push && sfifo_rcstage_full),
	(sfifo_rcstage_pop && !sfifo_rcstage_not_empty),
	(sfifo_rcstage_full && !sfifo_rcstage_not_empty)};

	assign cmd_upd_rdy_o = sfifo_rcstage_not_empty && !sfifo_keyvrc_full;

	//--------------------------------------------
	// final cmd block processing
	//--------------------------------------------

	prim_fifo_sync #(
	.Width(KeyVRCFifoWidth),
	.Pass(0),
	.Depth(KeyVRCFifoDepth),
	.OutputZeroIfEmpty(1'b0)
	) u_prim_fifo_sync_keyvrc (
	.clk_i (clk_i),
	.rst_ni (rst_ni),
	.clr_i (!ctr_drbg_cmd_enable_i),
	.wvalid_i (sfifo_keyvrc_push),
	.wready_o (),
	.wdata_i (sfifo_keyvrc_wdata),
	.rvalid_o (sfifo_keyvrc_not_empty),
	.rready_i (sfifo_keyvrc_pop),
	.rdata_o (sfifo_keyvrc_rdata),
	.full_o (sfifo_keyvrc_full),
	.depth_o (),
	.err_o ()
	);

	assign sfifo_keyvrc_push = sfifo_rcstage_pop;

	// if a UNI command, reset the state values
	assign sfifo_keyvrc_wdata = (rcstage_ccmd == UNI) ?
	{{(KeyLen+BlkLen+CtrLen+1+SeedLen){1'b0}},rcstage_glast,upd_cmd_inst_id_i,upd_cmd_ccmd_i} :
	gen_adata_null_q ?
	{rcstage_key,rcstage_v,rcstage_rc,rcstage_fips,
	rcstage_adata,rcstage_glast,rcstage_id,rcstage_ccmd} :
	{upd_cmd_key_i,upd_cmd_v_i,rcstage_rc,rcstage_fips,
	rcstage_adata,rcstage_glast,upd_cmd_inst_id_i,upd_cmd_ccmd_i};

	assign sfifo_keyvrc_pop = ctr_drbg_cmd_rdy_i && sfifo_keyvrc_not_empty;
	assign {ctr_drbg_cmd_key_o,ctr_drbg_cmd_v_o,ctr_drbg_cmd_rc_o,
	ctr_drbg_cmd_fips_o,ctr_drbg_cmd_adata_o,ctr_drbg_cmd_glast_o,
	ctr_drbg_cmd_inst_id_o,ctr_drbg_cmd_ccmd_o} = sfifo_keyvrc_rdata;

	assign ctr_drbg_cmd_sfifo_keyvrc_err_o =
	{(sfifo_keyvrc_push && sfifo_keyvrc_full),
	(sfifo_keyvrc_pop && !sfifo_keyvrc_not_empty),
	(sfifo_keyvrc_full && !sfifo_keyvrc_not_empty)};

	// block ack
	assign ctr_drbg_cmd_ack_o = sfifo_keyvrc_pop;

	assign ctr_drbg_cmd_sts_o = sfifo_keyvrc_pop && (ctr_drbg_cmd_ccmd_o == UNI) &&
	((KeyLen == '0) && (BlkLen == '0) && (CtrLen == '0));


	endmodule