// SPDX-License-Identifier: Apache-2.0
// Copyright 2019 Western Digital Corporation or its affiliates.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
`ifdef RV_BUILD_AHB_LITE

module ahb_sif (
input logic [63:0] HWDATA,
input logic HCLK,
input logic HSEL,
input logic [3:0] HPROT,
input logic HWRITE,
input logic [1:0] HTRANS,
input logic [2:0] HSIZE,
input logic HREADY,
input logic HRESETn,
input logic [31:0] HADDR,
input logic [2:0] HBURST,

output logic HREADYOUT,
output logic HRESP,
output logic [63:0] HRDATA
);

parameter MAILBOX_ADDR = 32'hD0580000;
// `define RV_ICCM_SADR 32'hee000000  
// `define RV_DCCM_SADR 32'hf0040000
parameter OFFSET_ADDR = 32'h00000000; 
parameter MEM_DEPTH = 15; // memory size = 0x8000 = 32k

logic write;
logic [31:0] laddr, addr;
logic [7:0] strb_lat;
logic [63:0] rdata;

bit [7:0] mem [bit[MEM_DEPTH-1:0]];
bit [7:0] wscnt;
int dws = 0;
int iws = 0;
bit dws_rand;
bit iws_rand;
bit ok;

// Wires
wire [63:0] WriteData = HWDATA;
wire [7:0] strb =  HSIZE == 3'b000 ? 8'h1 << HADDR[2:0] :
                   HSIZE == 3'b001 ? 8'h3 << {HADDR[2:1],1'b0} :
                   HSIZE == 3'b010 ? 8'hf << {HADDR[2],2'b0} : 8'hff;

wire [31:0] RDDR = HADDR - OFFSET_ADDR;

wire mailbox_write = write && laddr==MAILBOX_ADDR;


initial begin
    if ($value$plusargs("iws=%d", iws));
    if ($value$plusargs("dws=%d", dws));
    dws_rand = dws < 0;
    iws_rand = iws < 0;
end



always @ (negedge HCLK ) begin
    if(HREADY)
        addr = RDDR;
    if (write & HREADY) begin
        if(strb_lat[7]) mem[{laddr[MEM_DEPTH-1:3],3'd7}] = HWDATA[63:56];
        if(strb_lat[6]) mem[{laddr[MEM_DEPTH-1:3],3'd6}] = HWDATA[55:48];
        if(strb_lat[5]) mem[{laddr[MEM_DEPTH-1:3],3'd5}] = HWDATA[47:40];
        if(strb_lat[4]) mem[{laddr[MEM_DEPTH-1:3],3'd4}] = HWDATA[39:32];
        if(strb_lat[3]) mem[{laddr[MEM_DEPTH-1:3],3'd3}] = HWDATA[31:24];
        if(strb_lat[2]) mem[{laddr[MEM_DEPTH-1:3],3'd2}] = HWDATA[23:16];
        if(strb_lat[1]) mem[{laddr[MEM_DEPTH-1:3],3'd1}] = HWDATA[15:08];
        if(strb_lat[0]) mem[{laddr[MEM_DEPTH-1:3],3'd0}] = HWDATA[07:00];
    end
    if(HREADY & HSEL & |HTRANS) begin
`ifdef VERILATOR
        if(iws_rand & ~HPROT[0])
            iws = $random & 15;
        if(dws_rand & HPROT[0])
            dws = $random & 15;
`else
        if(iws_rand & ~HPROT[0])
            ok = std::randomize(iws) with {iws dist {0:=10, [1:3]:/2, [4:15]:/1};};
        if(dws_rand & HPROT[0])
            ok = std::randomize(dws) with {dws dist {0:=10, [1:3]:/2, [4:15]:/1};};
`endif
    end
end


assign HRDATA = HREADY ? rdata : ~rdata;
assign HREADYOUT = wscnt == 0;
assign HRESP = 0;

always @(posedge HCLK or negedge HRESETn) begin
    if(~HRESETn) begin
        laddr <= 32'b0;
        write <= 1'b0;
        rdata <= '0;
        wscnt <= 0;
    end
    else begin
        if(HREADY & HSEL) begin
            laddr <= RDDR;
            write <= HWRITE & |HTRANS;
            if(|HTRANS & ~HWRITE)
                rdata <= {mem[{addr[MEM_DEPTH-1:3],3'd7}],
                          mem[{addr[MEM_DEPTH-1:3],3'd6}],
                          mem[{addr[MEM_DEPTH-1:3],3'd5}],
                          mem[{addr[MEM_DEPTH-1:3],3'd4}],
                          mem[{addr[MEM_DEPTH-1:3],3'd3}],
                          mem[{addr[MEM_DEPTH-1:3],3'd2}],
                          mem[{addr[MEM_DEPTH-1:3],3'd1}],
                          mem[{addr[MEM_DEPTH-1:3],3'd0}]};
            strb_lat <= strb;
        end
    end
    if(HREADY & HSEL & |HTRANS)
        wscnt <= HPROT[0] ? dws[7:0] : iws[7:0];
    else if(wscnt != 0)
        wscnt <= wscnt-1;
end


endmodule
`endif