`timescale 1ns / 1ps
`include "sm3_cfg.v"
//////////////////////////////////////////////////////////////////////////////////
// Author:        ljgibbs / lf_gibbs@163.com
// Create Date: 2020/07/26 
// Design Name: sm3
// Module Name: sm3_expnd_core
// Description:
//      SM3 扩展模块-SM3 扩展核心单元
//      输入位宽：INPT_DW1 定义，支持32/64bit
//      输出位宽：与输入位宽对应
//      特性：预载寄存器（68->65clk(32b)/66->65clk(64b)）,目前仅支持32bit，默认开启
// Dependencies: 
//      inc/sm3_cfg.v
// Revision:
// Revision 0.01 - File Created
//////////////////////////////////////////////////////////////////////////////////
module sm3_expnd_core (
    input                       clk,
    input                       rst_n,

    input   [`INPT_DW1:0]       pad_inpt_d_i,
    input                       pad_inpt_vld_i,
    input                       pad_inpt_lst_i,

    input                       expnd_otpt_ena_i,

    output                      pad_inpt_rdy_o,

    output  [`INPT_DW1:0]       expnd_otpt_wj_o,                    
    output  [`INPT_DW1:0]       expnd_otpt_wjj_o,                    
    output                      expnd_otpt_lst_o,                  
    output                      expnd_otpt_vld_o                    
);

localparam              WORDS_IN_BLOCK = 512 / 32;//16
localparam              WORD_EXPND_ROUND = 64;
localparam              WORD_OUTPUT_ROUND_END = WORD_EXPND_ROUND + WORDS_IN_BLOCK; //64+16
localparam              PRE_BUFF_N = 4;

//字扩展电路
wire [31:0]             word_wj_expand;
wire [31:0]             word_wjj_expand;
wire [31:0]             word_wj_expand_tmp_1;
wire [31:0]             word_wj_expand_tmp_2;

wire                    word_exp_push_reg_ena;  //字拓展，并压入寄存器组使能

//寄存器组 reg
reg [31:0]              word_buff [15:0];   //16字缓冲区  缓存16个32位字
reg [31:0]              word_buff_nb_pre [3:0];//4字 下一字预缓存区
wire[31:0]              word_buff_new_push; //寄存器组，新入组变量
wire                    word_buff_shft_ena;  
wire                    word_buff_rpd_shft_ena;  
wire                    word_buff_nb_pre_shft_ena;  

//预缓冲区数据数量技术
reg [1:0]               word_buff_nb_pre_cntr;
wire                    word_buff_nb_pre_cntr_add;
wire                    word_buff_nb_pre_cntr_clr;

//原始字输入计数
reg [3:0]               msg_blk_word_inpt_cntr;  
wire                    msg_blk_word_inpt_cntr_add;
wire                    msg_blk_word_inpt_cntr_clr;

//字扩展输出计数，指本数据块中扩展电路的扩展字输出数量
reg [5:0]               msg_blk_word_exp_cntr;  
wire                    msg_blk_word_exp_cntr_add;
wire                    msg_blk_word_exp_cntr_clr;

//消息扩展主状态机
`define STT_W 8
`define STT_W1 `STT_W - 1

reg [`STT_W1:0]   state;
reg [`STT_W1:0]   nxt_state;

localparam IDLE                     = `STT_W'h1;
localparam INPT_ORGN_5W             = `STT_W'h2;//输入5个原始字w0-w4到寄存器组中
localparam INPT_OTPT                = `STT_W'h4;//输入剩下的11个原始字w5-w15，并输出11对扩展字
localparam EXP_OTPT                 = `STT_W'h8;//扩展并输出扩展字,直至扩展得到第48个扩展字w63
localparam EXP_OTPT_PRE_INPT        = `STT_W'h10;//当w64生成后，开始预接收下一消息块前3个消息字 wn0-wn2，消息字写入预存储寄存器
localparam EXP_OTPT_FIN             = `STT_W'h20;//扩展以及输出结束（输出最后一对扩展字）,接收下一消息块的第4个消息字 wn3,判断预存储器中数据数量
localparam WAT_PRE_INPT_FIN         = `STT_W'h40;//若预存储器数据数量>0 但 <4,等待预寄存器存储完成 4 字
localparam RPD_SHFT                 = `STT_W'h80;//快速移位原始数据,128b位宽的形式，包括预存储寄存器

//SM3填充消息输入反压逻辑
wire                    sm3_msg_inpt_rdy;

//消息最后一块标记信号
reg                     msg_lst_blk_flg;
wire                    msg_lst_blk_flg_ena;
wire                    msg_lst_blk_flg_clr;

//SM3填充消息输入反压逻辑，仅在 EXP_OTPT 状态下仅进行扩展，不提供输入
assign                  sm3_msg_inpt_rdy = (  state == IDLE 
                                        ||    state == INPT_ORGN_5W
                                        ||    state == INPT_OTPT     
                                        ||    state == EXP_OTPT_PRE_INPT     
                                        ||    state == EXP_OTPT_FIN        
                                        ||    state == WAT_PRE_INPT_FIN    
                                        ||    state == RPD_SHFT            
                                        ) ;
  
//原始字输入计数
always @(posedge clk or negedge rst_n) begin
    if(~rst_n) begin
        msg_blk_word_inpt_cntr              <= 4'b0;
    end else if(msg_blk_word_inpt_cntr_add)begin
        msg_blk_word_inpt_cntr              <= msg_blk_word_inpt_cntr + 1'b1;
    end else if(msg_blk_word_inpt_cntr_clr)begin
        msg_blk_word_inpt_cntr              <= 4'b0;
    end
end
assign                  msg_blk_word_inpt_cntr_add  = sm3_msg_valid_i; //输入计数累加
assign                  msg_blk_word_inpt_cntr_clr  = 1'b0; //自清？

//字扩展输出计数
always @(posedge clk or negedge rst_n) begin
    if(~rst_n) begin
        msg_blk_word_exp_cntr              <= 6'b0;
    end else if(msg_blk_word_exp_cntr_clr)begin
        msg_blk_word_exp_cntr              <= 6'b0;
    end else if(msg_blk_word_exp_cntr_add)begin
        msg_blk_word_exp_cntr              <= msg_blk_word_exp_cntr + 1'b1;
    end
end
assign                  msg_blk_word_exp_cntr_add  = word_exp_push_reg_ena;//字扩展并移入寄存器使能
assign                  msg_blk_word_exp_cntr_clr  = msg_blk_word_exp_cntr == 6'd52;//完成 68-16 次扩展后清除计数器

//预缓冲区数据数量计数
always @(posedge clk or negedge rst_n) begin
    if(~rst_n) begin
        word_buff_nb_pre_cntr              <= 2'b0;
    end else if(word_buff_nb_pre_cntr_add)begin
        word_buff_nb_pre_cntr              <= word_buff_nb_pre_cntr + 1'b1;
    end else if(word_buff_nb_pre_cntr_clr)begin
        word_buff_nb_pre_cntr              <= 2'b0;
    end
end
assign                  word_buff_nb_pre_cntr_add  = (  state == EXP_OTPT_PRE_INPT 
                                                    ||  state == EXP_OTPT_FIN  
                                                    ||  state == WAT_PRE_INPT_FIN  
                                                    ) && sm3_msg_valid_i;//预输入状态下的外部数据输入有效
assign                  word_buff_nb_pre_cntr_clr  = state == RPD_SHFT ;//预输入寄存器该状态下被移出

//消息最后一块标记信号
always @(posedge clk or negedge rst_n) begin
    if(~rst_n) begin
        msg_lst_blk_flg              <= 1'b0;
    end else if(msg_lst_blk_flg_ena)begin
        msg_lst_blk_flg              <= 1'b1;
    end else if(msg_lst_blk_flg_clr)begin
        msg_lst_blk_flg              <= 1'b0;
    end
end

assign                  msg_lst_blk_flg_ena  = sm3_msg_lst_i;
assign                  msg_lst_blk_flg_clr  = sm3_wj_wjj_lst_o;

//消息扩展主状态机
always @(*) begin
    case (state)
        IDLE: begin
            if(sm3_msg_valid_i)
                nxt_state   =   INPT_ORGN_5W;
            else
                nxt_state   =   IDLE;
        end
        INPT_ORGN_5W:begin
            if(msg_blk_word_inpt_cntr == 4'd4 && sm3_msg_valid_i) 
                nxt_state   =   INPT_OTPT;//输入前 5 个原始字后，开始一边输入，一边输出
            else
                nxt_state   =   INPT_ORGN_5W;
        end
        INPT_OTPT:begin
            if(msg_blk_word_inpt_cntr == 4'd15 && sm3_msg_valid_i) 
                nxt_state   =   EXP_OTPT;//输入所有 16 个原始字后，开始向寄存器组输入扩展字
            else
                nxt_state   =   INPT_OTPT;
        end
        EXP_OTPT:begin
            if(msg_blk_word_exp_cntr == 6'd48) 
                nxt_state   =   EXP_OTPT_PRE_INPT; //在生成w63（第48个扩展字后）后，允许下一个块预输入 
            else
                nxt_state   =   EXP_OTPT;
        end
        EXP_OTPT_PRE_INPT:begin
            if(msg_blk_word_exp_cntr == 6'd51) 
                nxt_state   =   EXP_OTPT_FIN; //在生成51个扩展字后,转入最后一个扩展字 
            else
                nxt_state   =   EXP_OTPT_PRE_INPT;
        end
        EXP_OTPT_FIN:begin
            if(word_buff_nb_pre_cntr == 2'd0 && ~sm3_msg_valid_i) 
                nxt_state   =   IDLE; //扩展期间无预缓存字，转为idle，等待下次输入
            else if(word_buff_nb_pre_cntr == 2'd3 && sm3_msg_valid_i)
                nxt_state   =   RPD_SHFT;//4 个预缓存字，转入 RPD_SHFT
            else 
                nxt_state   =   WAT_PRE_INPT_FIN;//存在预缓存字，转入 WAT_PRE_INPT_FIN，等待条件满足
        end
        WAT_PRE_INPT_FIN:begin
            if(word_buff_nb_pre_cntr == 2'd3 && sm3_msg_valid_i) 
                nxt_state   =   RPD_SHFT; //4 个预缓存字，转入 RPD_SHFT
            else 
                nxt_state   =   WAT_PRE_INPT_FIN;//存在预缓存字，转入WAT_PRE_INPT_FIN
        end
        RPD_SHFT:begin
            if(sm3_msg_valid_i) 
                nxt_state   =   INPT_OTPT; //5个原始字输入完毕，开始一边输入，一边输出
            else
                nxt_state   =   RPD_SHFT;//等待第5个原始字
        end
        default: 
            nxt_state   =   IDLE;
    endcase
end

always @(posedge clk or negedge rst_n) begin
    if(~rst_n)
        state   <=  `STT_W'b1;
    else begin
        state   <=  nxt_state;
    end  
end

//扩展电路
assign                  word_wj_expand_tmp_1        =   word_buff[0] ^ word_buff[7] ^ {word_buff[13][16:0],word_buff[13][31:17]};
assign                  word_wj_expand_tmp_2        =   {word_wj_expand_tmp_1 ^ {word_wj_expand_tmp_1[16:0],word_wj_expand_tmp_1[31:17]} 
                                                                                ^ {word_wj_expand_tmp_1[8:0],word_wj_expand_tmp_1[31:9]}};

assign                  word_wj_expand              =   word_wj_expand_tmp_2 ^ word_buff[10] ^ {word_buff[3][24:0],word_buff[3][31:25]};
assign                  word_wjj_expand             =   word_buff[11] ^ word_buff[15];//从寄存器后段输出

//扩展电路输出使能
assign                  word_exp_push_reg_ena       =   (state == EXP_OTPT         
                                                    ||   state == EXP_OTPT_PRE_INPT
                                                    ||   state == EXP_OTPT_FIN     
                                                        );

// 根据当前扩展轮数，确定补充进缓冲区的数据类型：原始数据(0-15) 扩展数据(16-67) 0( >67)
assign                  word_buff_new_push          =   (state == IDLE
                                                    ||   state == INPT_ORGN_5W
                                                    ||   state == RPD_SHFT
                                                    ||   state == INPT_OTPT 
                                                        ) ? sm3_msg_i : 
                                                        word_exp_push_reg_ena ? word_wj_expand : 
                                                        32'd0;

//消息缓冲区 push
always @(posedge clk or negedge rst_n) begin
    if(~rst_n) begin : buff_init
        integer i;
        for ( i = 0 ; i < WORDS_IN_BLOCK; i = i + 1) begin:buff_init
            word_buff[i]                <=      32'd0;          
        end
    end
    else if(word_buff_shft_ena)begin : buff_shift // w0 <- w1; w1 <- w2;....w15 <- w_new
        integer i;
        for ( i = WORDS_IN_BLOCK - 1 ; i > 0 ; i = i - 1) begin
            word_buff[i-1]                  <=      word_buff[i];    
        end
        word_buff[15]                   <=      word_buff_new_push;      
    end
    else if(word_buff_rpd_shft_ena)begin : buff_rpd_shift //快速移位阶段
        word_buff[15]                   <=      sm3_msg_i;      
        word_buff[14]                   <=      word_buff_nb_pre[3];      
        word_buff[13]                   <=      word_buff_nb_pre[2];      
        word_buff[12]                   <=      word_buff_nb_pre[1];      
        word_buff[11]                   <=      word_buff_nb_pre[0];      
    end
end

assign                  word_buff_shft_ena      =   (state == IDLE && sm3_msg_valid_i)
                                                ||  (state == INPT_ORGN_5W  && sm3_msg_valid_i)
                                                ||  (state == INPT_OTPT     && sm3_msg_valid_i)
                                                ||  state == EXP_OTPT 
                                                ||  state == EXP_OTPT_PRE_INPT 
                                                ||  state == EXP_OTPT_FIN 
                                                ;//寄存器组左移使能 20.5.13 fix
assign                  word_buff_rpd_shft_ena  =   state == RPD_SHFT && sm3_msg_valid_i; //缓存区快速移位使能 

//消息预缓冲区
always @(posedge clk or negedge rst_n) begin
    if(~rst_n) begin : pre_buff_init
        integer i;
        for ( i = 0 ; i < PRE_BUFF_N; i = i + 1) begin : pre_buff_init
            word_buff_nb_pre[i]                <=      32'd0;          
        end
    end
    else if(word_buff_nb_pre_shft_ena)begin : pre_buff_shift // wnb0 <- wnb1....wnb3 <- input
        integer i;
        for ( i = PRE_BUFF_N - 1 ; i > 0 ; i = i - 1) begin
            word_buff_nb_pre[i-1]                  <=      word_buff_nb_pre[i];    
        end
        word_buff_nb_pre[PRE_BUFF_N - 1]                   <=      sm3_msg_i;      
    end
end

assign                  word_buff_nb_pre_shft_ena   =   (   state == EXP_OTPT_PRE_INPT
                                                        ||  state == EXP_OTPT_FIN 
                                                        ||  state == WAT_PRE_INPT_FIN 
                                                        ) && sm3_msg_valid_i;//预缓冲区移位使能

//输出控制
assign                  sm3_wj_o                =  word_buff[11];// 从倒数第5个寄存器输出
assign                  sm3_wjj_o               =  word_wjj_expand;
assign                  sm3_wj_wjj_valid_o      =  (state == INPT_OTPT && sm3_msg_valid_i) //20.5.13 fix   
                                                ||  state == EXP_OTPT         
                                                ||  state == EXP_OTPT_PRE_INPT
                                                ||  state == EXP_OTPT_FIN
                                                    ;
assign                  sm3_wj_wjj_lst_o        =  msg_lst_blk_flg && state == EXP_OTPT_FIN;
assign                  sm3_msg_rdy_o           =  sm3_msg_inpt_rdy; //反压控制

//调试用
`ifdef SM3_TOP_SIM
    generate
        if(MODULE_SIM) begin
            always@(*) begin		
                if(sm3_wj_wjj_valid_o)
                begin
                    $display(" %32h|%32h", sm3_wj_o[31:0],sm3_wjj_o[31:0],);
                end
            end
        end
    endgenerate
`endif

endmodule