// ================================================================
// NVDLA Open Source Project
//
// Copyright(c) 2016 - 2017 NVIDIA Corporation. Licensed under the
// NVDLA Open Hardware License; Check "LICENSE" which comes with
// this distribution for more information.
// ================================================================
// File Name: NV_NVDLA_CDMA_WT_fifo.v
`define FORCE_CONTENTION_ASSERTION_RESET_ACTIVE 1'b1
`include "simulate_x_tick.vh"
module NV_NVDLA_CDMA_WT_fifo (
      clk
    , reset_
    , wr_ready
    , wr_req
    , wr_data
    , rd_ready
    , rd_req
    , rd_data
    , pwrbus_ram_pd
    );
// spyglass disable_block W401 -- clock is not input to module
input clk;
input reset_;
output wr_ready;
input wr_req;
input [5:0] wr_data;
input rd_ready;
output rd_req;
output [5:0] rd_data;
input [31:0] pwrbus_ram_pd;
// Master Clock Gating (SLCG)
//
// We gate the clock(s) when idle or stalled.
// This allows us to turn off numerous miscellaneous flops
// that don't get gated during synthesis for one reason or another.
//
// We gate write side and read side separately.
// If the fifo is synchronous, we also gate the ram separately, but if
// -master_clk_gated_unified or -status_reg/-status_logic_reg is specified,
// then we use one clk gate for write, ram, and read.
//
wire clk_mgated_enable; // assigned by code at end of this module
wire clk_mgated; // used only in synchronous fifos
NV_CLK_gate_power clk_mgate( .clk(clk), .reset_(reset_), .clk_en(clk_mgated_enable), .clk_gated(clk_mgated) );
//
// WRITE SIDE
//
wire wr_reserving;
reg wr_req_in; // registered wr_req
reg [5:0] wr_data_in; // registered wr_data
reg wr_busy_in; // inputs being held this cycle?
assign wr_ready = !wr_busy_in;
wire wr_busy_next; // fwd: fifo busy next?
// factor for better timing with distant wr_req signal
wire wr_busy_in_next_wr_req_eq_1 = wr_busy_next;
wire wr_busy_in_next_wr_req_eq_0 = (wr_req_in && wr_busy_next) && !wr_reserving;
wire wr_busy_in_next = (wr_req? wr_busy_in_next_wr_req_eq_1 : wr_busy_in_next_wr_req_eq_0)
                               ;
wire wr_busy_in_int;
always @( posedge clk or negedge reset_ ) begin
    if ( !reset_ ) begin
        wr_req_in <= 1'b0;
        wr_busy_in <= 1'b0;
    end else begin
        wr_busy_in <= wr_busy_in_next;
        if ( !wr_busy_in_int ) begin
            wr_req_in <= wr_req && !wr_busy_in;
        end
//synopsys translate_off
            else if ( wr_busy_in_int ) begin
        end else begin
            wr_req_in <= `x_or_0;
        end
//synopsys translate_on
    end
end
always @( posedge clk ) begin
    if ( !wr_busy_in && wr_req ) begin
        wr_data_in <= wr_data;
    end
//synopsys translate_off
        else if ( !(!wr_busy_in && wr_req) ) begin
    end else begin
        wr_data_in <= {6{`x_or_0}};
    end
//synopsys translate_on
end
reg wr_busy_int; // copy for internal use
assign wr_reserving = wr_req_in && !wr_busy_int; // reserving write space?
reg wr_popping; // fwd: write side sees pop?
reg [7:0] wr_count; // write-side count
wire [7:0] wr_count_next_wr_popping = wr_reserving ? wr_count : (wr_count - 1'd1); // spyglass disable W164a W484
wire [7:0] wr_count_next_no_wr_popping = wr_reserving ? (wr_count + 1'd1) : wr_count; // spyglass disable W164a W484
wire [7:0] wr_count_next = wr_popping ? wr_count_next_wr_popping :
                                               wr_count_next_no_wr_popping;
wire wr_count_next_no_wr_popping_is_128 = ( wr_count_next_no_wr_popping == 8'd128 );
wire wr_count_next_is_128 = wr_popping ? 1'b0 :
                                          wr_count_next_no_wr_popping_is_128;
wire [7:0] wr_limit_muxed; // muxed with simulation/emulation overrides
wire [7:0] wr_limit_reg = wr_limit_muxed;
// VCS coverage off
assign wr_busy_next = wr_count_next_is_128 || // busy next cycle?
                          (wr_limit_reg != 8'd0 && // check wr_limit if != 0
                           wr_count_next >= wr_limit_reg) ;
// VCS coverage on
assign wr_busy_in_int = wr_req_in && wr_busy_int;
always @( posedge clk_mgated or negedge reset_ ) begin
    if ( !reset_ ) begin
        wr_busy_int <= 1'b0;
        wr_count <= 8'd0;
    end else begin
 wr_busy_int <= wr_busy_next;
 if ( wr_reserving ^ wr_popping ) begin
     wr_count <= wr_count_next;
        end
//synopsys translate_off
            else if ( !(wr_reserving ^ wr_popping) ) begin
        end else begin
            wr_count <= {8{`x_or_0}};
        end
//synopsys translate_on
    end
end
wire wr_pushing = wr_reserving; // data pushed same cycle as wr_req_in
//
// RAM
//
reg [6:0] wr_adr; // current write address
wire [6:0] rd_adr_p; // read address to use for ram
wire [5:0] rd_data_p; // read data directly out of ram
wire rd_enable;
wire ore;
wire [31 : 0] pwrbus_ram_pd;
// Adding parameter for fifogen to disable wr/rd contention assertion in ramgen.
// Fifogen handles this by ignoring the data on the ram data out for that cycle.
nv_ram_rwsp_128x6 #(`FORCE_CONTENTION_ASSERTION_RESET_ACTIVE) ram (
      .clk ( clk )
    , .pwrbus_ram_pd ( pwrbus_ram_pd )
    , .wa ( wr_adr )
    , .we ( wr_pushing )
    , .di ( wr_data_in )
    , .ra ( rd_adr_p )
    , .re ( rd_enable )
    , .dout ( rd_data_p )
    , .ore ( ore )
    );
// next wr_adr if wr_pushing=1
wire [6:0] wr_adr_next = wr_adr + 1'd1; // spyglass disable W484
// spyglass disable_block W484
always @( posedge clk_mgated or negedge reset_ ) begin
    if ( !reset_ ) begin
        wr_adr <= 7'd0;
    end else begin
        if ( wr_pushing ) begin
            wr_adr <= wr_adr_next;
        end
//synopsys translate_off
            else if ( !(wr_pushing) ) begin
        end else begin
            wr_adr <= {7{`x_or_0}};
        end
//synopsys translate_on
    end
end
// spyglass enable_block W484
wire rd_popping; // read side doing pop this cycle?
reg [6:0] rd_adr; // current read address
// next read address
wire [6:0] rd_adr_next = rd_adr + 1'd1; // spyglass disable W484
assign rd_adr_p = rd_popping ? rd_adr_next : rd_adr; // for ram
// spyglass disable_block W484
always @( posedge clk_mgated or negedge reset_ ) begin
    if ( !reset_ ) begin
        rd_adr <= 7'd0;
    end else begin
        if ( rd_popping ) begin
     rd_adr <= rd_adr_next;
        end
//synopsys translate_off
            else if ( !rd_popping ) begin
        end else begin
            rd_adr <= {7{`x_or_0}};
        end
//synopsys translate_on
    end
end
// spyglass enable_block W484
//
// SYNCHRONOUS BOUNDARY
//
always @( posedge clk_mgated or negedge reset_ ) begin
    if ( !reset_ ) begin
        wr_popping <= 1'b0;
    end else begin
 wr_popping <= rd_popping;
    end
end
reg rd_pushing;
always @( posedge clk_mgated or negedge reset_ ) begin
    if ( !reset_ ) begin
        rd_pushing <= 1'b0;
    end else begin
 rd_pushing <= wr_pushing; // let data go into ram first
    end
end
//
// READ SIDE
//
reg rd_req_p; // data out of fifo is valid
reg rd_req_int; // internal copy of rd_req
assign rd_req = rd_req_int;
assign rd_popping = rd_req_p && !(rd_req_int && !rd_ready);
reg [7:0] rd_count_p; // read-side fifo count
// spyglass disable_block W164a W484
wire [7:0] rd_count_p_next_rd_popping = rd_pushing ? rd_count_p :
                                                                (rd_count_p - 1'd1);
wire [7:0] rd_count_p_next_no_rd_popping = rd_pushing ? (rd_count_p + 1'd1) :
                                                                    rd_count_p;
// spyglass enable_block W164a W484
wire [7:0] rd_count_p_next = rd_popping ? rd_count_p_next_rd_popping :
                                                     rd_count_p_next_no_rd_popping;
wire rd_count_p_next_rd_popping_not_0 = rd_count_p_next_rd_popping != 0;
wire rd_count_p_next_no_rd_popping_not_0 = rd_count_p_next_no_rd_popping != 0;
wire rd_count_p_next_not_0 = rd_popping ? rd_count_p_next_rd_popping_not_0 :
                                              rd_count_p_next_no_rd_popping_not_0;
assign rd_enable = ((rd_count_p_next_not_0) && ((~rd_req_p) || rd_popping)); // anytime data's there and not stalled
always @( posedge clk_mgated or negedge reset_ ) begin
    if ( !reset_ ) begin
        rd_count_p <= 8'd0;
        rd_req_p <= 1'b0;
    end else begin
        if ( rd_pushing || rd_popping ) begin
     rd_count_p <= rd_count_p_next;
        end
//synopsys translate_off
            else if ( !(rd_pushing || rd_popping ) ) begin
        end else begin
            rd_count_p <= {8{`x_or_0}};
        end
//synopsys translate_on
        if ( rd_pushing || rd_popping ) begin
     rd_req_p <= (rd_count_p_next_not_0);
        end
//synopsys translate_off
            else if ( !(rd_pushing || rd_popping ) ) begin
        end else begin
            rd_req_p <= `x_or_0;
        end
//synopsys translate_on
    end
end
wire rd_req_next = (rd_req_p || (rd_req_int && !rd_ready)) ;
always @( posedge clk_mgated or negedge reset_ ) begin
    if ( !reset_ ) begin
        rd_req_int <= 1'b0;
    end else begin
        rd_req_int <= rd_req_next;
    end
end
assign rd_data = rd_data_p;
assign ore = rd_popping;
// Master Clock Gating (SLCG) Enables
//
// plusarg for disabling this stuff:
// synopsys translate_off
`ifndef SYNTH_LEVEL1_COMPILE
`ifndef SYNTHESIS
reg master_clk_gating_disabled; initial master_clk_gating_disabled = $test$plusargs( "fifogen_disable_master_clk_gating" ) != 0;
`endif
`endif
// synopsys translate_on
assign clk_mgated_enable = ((wr_reserving || wr_pushing || rd_popping || wr_popping || (wr_req_in && !wr_busy_int) || (wr_busy_int != wr_busy_next)) || (rd_pushing || rd_popping || (rd_req_int && rd_ready) || wr_pushing))
                               `ifdef FIFOGEN_MASTER_CLK_GATING_DISABLED
                               || 1'b1
                               `endif
// synopsys translate_off
          `ifndef SYNTH_LEVEL1_COMPILE
          `ifndef SYNTHESIS
                               || master_clk_gating_disabled
          `endif
          `endif
// synopsys translate_on
                               ;
// Simulation and Emulation Overrides of wr_limit(s)
//
`ifdef EMU
`ifdef EMU_FIFO_CFG
// Emulation Global Config Override
//
assign wr_limit_muxed = `EMU_FIFO_CFG.NV_NVDLA_CDMA_WT_fifo_wr_limit_override ? `EMU_FIFO_CFG.NV_NVDLA_CDMA_WT_fifo_wr_limit : 8'd0;
`else
// No Global Override for Emulation
//
assign wr_limit_muxed = 8'd0;
`endif // EMU_FIFO_CFG
`else // !EMU
`ifdef SYNTH_LEVEL1_COMPILE
// No Override for GCS Compiles
//
assign wr_limit_muxed = 8'd0;
`else
`ifdef SYNTHESIS
// No Override for RTL Synthesis
//
assign wr_limit_muxed = 8'd0;
`else
// RTL Simulation Plusarg Override
// VCS coverage off
reg wr_limit_override;
reg [7:0] wr_limit_override_value;
assign wr_limit_muxed = wr_limit_override ? wr_limit_override_value : 8'd0;
`ifdef NV_ARCHPRO
event reinit;
initial begin
    $display("fifogen reinit initial block %m");
    -> reinit;
end
`endif
`ifdef NV_ARCHPRO
always @( reinit ) begin
`else
initial begin
`endif
    wr_limit_override = 0;
    wr_limit_override_value = 0; // to keep viva happy with dangles
    if ( $test$plusargs( "NV_NVDLA_CDMA_WT_fifo_wr_limit" ) ) begin
        wr_limit_override = 1;
        $value$plusargs( "NV_NVDLA_CDMA_WT_fifo_wr_limit=%d", wr_limit_override_value);
    end
end
// VCS coverage on
`endif
`endif
`endif
//
// Histogram of fifo depth (from write side's perspective)
//
// NOTE: it will reference `SIMTOP.perfmon_enabled, so that
// has to at least be defined, though not initialized.
// tbgen testbenches have it already and various
// ways to turn it on and off.
//
`ifdef PERFMON_HISTOGRAM
// synopsys translate_off
`ifndef SYNTH_LEVEL1_COMPILE
`ifndef SYNTHESIS
perfmon_histogram perfmon (
      .clk ( clk )
    , .max ( {24'd0, (wr_limit_reg == 8'd0) ? 8'd128 : wr_limit_reg} )
    , .curr ( {24'd0, wr_count} )
    );
`endif
`endif
// synopsys translate_on
`endif
// spyglass disable_block W164a W164b W116 W484 W504
`ifdef SPYGLASS
`else
`ifdef FV_ASSERT_ON
`else
// synopsys translate_off
`endif
`ifdef ASSERT_ON
`ifdef SPYGLASS
wire disable_assert_plusarg = 1'b0;
`else
`ifdef FV_ASSERT_ON
wire disable_assert_plusarg = 1'b0;
`else
wire disable_assert_plusarg = $test$plusargs("DISABLE_NESS_FLOW_ASSERTIONS");
`endif
`endif
wire assert_enabled = 1'b1 && !disable_assert_plusarg;
`endif
`ifdef FV_ASSERT_ON
`else
// synopsys translate_on
`endif
`ifdef ASSERT_ON
//synopsys translate_off
`ifndef SYNTH_LEVEL1_COMPILE
`ifndef SYNTHESIS
always @(assert_enabled) begin
    if ( assert_enabled === 1'b0 ) begin
        $display("Asserts are disabled for %m");
    end
end
`endif
`endif
//synopsys translate_on
`endif
`endif
// spyglass enable_block W164a W164b W116 W484 W504
//The NV_BLKBOX_SRC0 module is only present when the FIFOGEN_MODULE_SEARCH
// define is set. This is to aid fifogen team search for fifogen fifo
// instance and module names in a given design.
`ifdef FIFOGEN_MODULE_SEARCH
NV_BLKBOX_SRC0 dummy_breadcrumb_fifogen_blkbox (.Y());
`endif
// spyglass enable_block W401 -- clock is not input to module
// synopsys dc_script_begin
// set_boundary_optimization find(design, "NV_NVDLA_CDMA_WT_fifo") true
// synopsys dc_script_end
endmodule // NV_NVDLA_CDMA_WT_fifo