`include "timescale.v"
`include "wb_model_defines.v"
// WISHBONE bus monitor module - it connects to WISHBONE master signals and
// monitors for any illegal combinations appearing on the bus.
module WB_BUS_MON(
                    CLK_I,
                    RST_I,
	            ACK_I,
                    ADDR_O,
                    CYC_O,
                    DAT_I,
                    DAT_O,
                    ERR_I,
                    RTY_I,
                    SEL_O,
                    STB_O,
                    WE_O,
                    TAG_I,
                    TAG_O,
                    CAB_O,
                    log_file_desc
                  ) ;

input                           CLK_I  ;
input                           RST_I  ;
input                           ACK_I  ;
input   [(`WB_ADDR_WIDTH-1):0]  ADDR_O ;
input                           CYC_O  ;
input   [(`WB_DATA_WIDTH-1):0]  DAT_I  ;
input   [(`WB_DATA_WIDTH-1):0]  DAT_O  ;
input                           ERR_I  ;
input                           RTY_I  ;
input   [(`WB_SEL_WIDTH-1):0]   SEL_O  ;
input                           STB_O  ;
input                           WE_O   ;
input   [(`WB_TAG_WIDTH-1):0] TAG_I  ;
input   [(`WB_TAG_WIDTH-1):0] TAG_O  ;
input                           CAB_O  ;
input [31:0] log_file_desc ;

always@(posedge CLK_I or posedge RST_I)
begin
    if (RST_I)
    begin
        // when reset is applied, all control signals must be low
        if (CYC_O)
        begin
            $display("*E (%0t) CYC_O active under reset", $time) ;
            $fdisplay(log_file_desc, "*E (%0t)(%m)CYC_O active under reset", $time) ;
        end
        if (STB_O)
        begin
            $display("*E (%0t) STB_O active under reset", $time) ;
            $fdisplay(log_file_desc, "*E (%0t)(%m)STB_O active under reset", $time) ;
        end
        /*if (ACK_I)
            $display("ACK_I active under reset") ;*/
        if (ERR_I)
        begin
            $display("*E (%0t) ERR_I active under reset", $time) ;
            $fdisplay(log_file_desc, "*E (%0t)(%m)ERR_I active under reset", $time) ;
        end
        if (RTY_I)
        begin
            $display("*E (%0t) RTY_I active under reset", $time) ;
            $fdisplay(log_file_desc, "*E (%0t)(%m)RTY_I active under reset", $time) ;
        end
        if (CAB_O)
        begin
            $display("*E (%0t) CAB_O active under reset", $time) ;
            $fdisplay(log_file_desc, "*E (%0t)(%m)CAB_O active under reset", $time) ;
        end
    end // reset
    else
    if (~CYC_O)
    begin
        // when cycle indicator is low, all control signals must be low
        if (STB_O)
        begin
            $display("*E (%0t) STB_O active without CYC_O being active", $time) ;
            $fdisplay(log_file_desc, "*E (%0t)(%m)STB_O active without CYC_O being active", $time) ;
        end
        if (ACK_I)
        begin
            $display("*E (%0t) ACK_I active without CYC_O being active", $time) ;
            $fdisplay(log_file_desc, "*E (%0t)(%m)ACK_I active without CYC_O being active", $time) ;
        end
        if (ERR_I)
        begin
            $display("*E (%0t) ERR_I active without CYC_O being active", $time) ;
            $fdisplay(log_file_desc, "*E (%0t)(%m)ERR_I active without CYC_O being active", $time) ;
        end
        if (RTY_I)
        begin
            $display("*E (%0t) RTY_I active without CYC_O being active", $time) ;
            $fdisplay(log_file_desc, "*E (%0t)(%m)RTY_I active without CYC_O being active", $time) ;
        end
        if (CAB_O)
        begin
            $display("*E (%0t) CAB_O active without CYC_O being active", $time) ;
            $fdisplay(log_file_desc, "*E (%0t)(%m)CAB_O active without CYC_O being active", $time) ;
        end
    end // ~CYC_O
end

reg [`WB_DATA_WIDTH-1:0] previous_data ;
reg [`WB_ADDR_WIDTH-1:0] previous_address ;
reg [`WB_SEL_WIDTH-1:0] previous_sel ;
reg                     previous_stb ;
reg                     previous_ack ;
reg                     previous_err ;
reg                     previous_rty ;
reg                     previous_cyc ;
reg can_change ;

always@(posedge CLK_I or posedge RST_I)
begin
    if (RST_I)
    begin
        previous_stb <= 1'b0 ;
        previous_ack <= 1'b0 ;
        previous_err <= 1'b0 ;
        previous_rty <= 1'b0 ;
        previous_cyc <= 1'b0 ;
    end
    else
    begin
        previous_stb <= STB_O ;
        previous_ack <= ACK_I ;
        previous_err <= ERR_I ;
        previous_rty <= RTY_I ;
        previous_cyc <= CYC_O ;
    end
end

// cycle monitor
always@(posedge CLK_I)
begin
    if (CYC_O && ~RST_I) // cycle in progress
    begin
        if (STB_O)
        begin
            // check for two control signals active at same edge
            if ( ACK_I && RTY_I )
            begin
                $display("*E (%0t) ACK_I and RTY_I asserted at the same time during cycle", $time) ;
                $fdisplay(log_file_desc, "*E (%0t)(%m)ACK_I and RTY_I asserted at the same time during cycle", $time) ;
            end
            if ( ACK_I && ERR_I )
            begin
                $display("*E (%0t) ACK_I and ERR_I asserted at the same time during cycle", $time) ;
                $fdisplay(log_file_desc, "*E (%0t)(%m)ACK_I and ERR_I asserted at the same time during cycle", $time) ;
            end
            if ( RTY_I && ERR_I )
            begin
                $display("*E (%0t) RTY_I and ERR_I asserted at the same time during cycle", $time) ;
                $fdisplay(log_file_desc, "*E (%0t)(%m)RTY_I and ERR_I asserted at the same time during cycle", $time) ;
            end

            if ( can_change !== 1 )
            begin
                if ( ADDR_O !== previous_address )
                begin
                    $display("*E (%0t) WB bus monitor detected address change in the middle of the cycle!", $time) ;
                    $fdisplay(log_file_desc, "*E (%0t)(%m)WB bus monitor detected address change in the middle of the cycle!", $time) ;
                end

                if ( SEL_O !== previous_sel )
                begin
                    $display("*E (%0t) WB bus monitor detected select lines changed in the middle of the cycle!", $time) ;
                    $fdisplay(log_file_desc, "*E (%0t)(%m)WB bus monitor detected select lines changed in the middle of the cycle!", $time) ;
                end

                if ( (WE_O !== 0) && ( DAT_O !== previous_data ) )
                begin
                    $display("*E (%0t) WB bus monitor detected data lines changed in the middle of the cycle!", $time) ;
                    $fdisplay(log_file_desc, "*E (%0t)(%m)WB bus monitor detected data lines changed in the middle of the cycle!", $time) ;
                end
            end

            if ( ACK_I || RTY_I || ERR_I )
                can_change       = 1 ;
            else
            begin
                previous_data    = DAT_O ;
                previous_address = ADDR_O ;
                previous_sel     = SEL_O ;
                can_change = 0 ;
            end

        end // STB_O
        else
        begin //~STB_O
            // while STB_O is inactive, only ACK_I is allowed to be active
            if ( ERR_I )
            begin
                $display("*E (%0t) ERR_I asserted during cycle without STB_O", $time) ;
                $fdisplay(log_file_desc, "*E (%0t)(%m)ERR_I asserted during cycle without STB_O", $time) ;
            end
            if ( RTY_I )
            begin
                $display("*E (%0t) RTY_I asserted during cycle without STB_O", $time) ;
                $fdisplay(log_file_desc, "*E (%0t)(%m)RTY_I asserted during cycle without STB_O", $time) ;
            end

            if ((previous_ack !== 1) && (previous_err !== 1) && (previous_rty !== 1) && (previous_stb !== 0))
            begin
                $display("STB_O de-asserted without reception of slave response") ;
                $fdisplay(log_file_desc, "STB_O de-asserted without reception of slave response") ;
            end

            can_change = 1 ;
        end   // ~STB_O
    end // cycle in progress
    else if (!RST_I)
    begin
        // cycle not in progress anymore
        can_change = 1 ;
        if ((previous_ack !== 1) && (previous_err !== 1) && (previous_rty !== 1) && (previous_stb !== 0))
        begin
            $display("STB_O de-asserted without reception of slave response") ;
            $fdisplay(log_file_desc, "STB_O de-asserted without reception of slave response") ;
        end
    end
end // cycle monitor

// CAB_O monitor - CAB_O musn't change during one cycle
reg [1:0] first_cab_val ;
always@(posedge CLK_I or RST_I)
begin
    if ((CYC_O === 0) || RST_I)
        first_cab_val <= 2'b00 ;
    else
    begin
        // cycle in progress - is this first clock edge in a cycle ?
        if (first_cab_val[1] === 1'b0)
            first_cab_val <= {1'b1, CAB_O} ;
        else if ( first_cab_val[0] !== CAB_O )
        begin
            $display("*E (%0t) CAB_O value changed during cycle", $time) ;
            $fdisplay(log_file_desc, "*E (%0t)(%m)CAB_O value changed during cycle", $time) ;
        end
    end
end // CAB_O monitor

// WE_O monitor for consecutive address bursts
reg [1:0] first_we_val ;
always@(posedge CLK_I or posedge RST_I)
begin
    if (~CYC_O || ~CAB_O || RST_I)
        first_we_val <= 2'b00 ;
    else
    if (STB_O)
    begin
        // cycle in progress - is this first clock edge in a cycle ?
        if (first_we_val[1] == 1'b0)
            first_we_val <= {1'b1, WE_O} ;
        else if ( first_we_val[0] != WE_O )
        begin
            $display("*E (%0t) WE_O value changed during CAB cycle", $time) ;
            $fdisplay(log_file_desc, "*E (%0t)(%m)WE_O value changed during CAB cycle", $time) ;
        end
    end
end // CAB_O monitor

// address monitor for consecutive address bursts
reg [`WB_ADDR_WIDTH:0] address ;
always@(posedge CLK_I or posedge RST_I)
begin
    if (~CYC_O || ~CAB_O || RST_I)
        address <= {(`WB_ADDR_WIDTH + 1){1'b0}} ;
    else
    begin
        if (STB_O && ACK_I)
        begin
            if (address[`WB_ADDR_WIDTH] == 1'b0)
                address <= {1'b1, (ADDR_O + `WB_SEL_WIDTH)} ;
            else
            begin
                if ( address[(`WB_ADDR_WIDTH-1):0] != ADDR_O)
                begin
                    $display("*E (%0t) Consecutive address burst address incrementing incorrect", $time) ;
                    $fdisplay(log_file_desc, "*E (%0t)(%m)Consecutive address burst address incrementing incorrect", $time) ;
                end
                else
                    address <= {1'b1, (ADDR_O + `WB_SEL_WIDTH)} ;
            end
        end
    end
end // address monitor

// data monitor
always@(posedge CLK_I or posedge RST_I)
begin
    if (CYC_O && STB_O && ~RST_I)
    begin
        if ( ((^ADDR_O) !== 1'b1) && ((^ADDR_O) !== 1'b0) )
        begin
            $display("*E (%0t) Master provided invalid address and qualified it with STB_O", $time) ;
            $fdisplay(log_file_desc, "*E (%0t)(%m)Master provided invalid address and qualified it with STB_O", $time) ;
        end
        if ( WE_O )
        begin
            if (
                (SEL_O[0] && (((^DAT_O[7:0])   !== 1'b0) && ((^DAT_O[7:0])   !== 1'b1))) ||
                (SEL_O[1] && (((^DAT_O[15:8])  !== 1'b0) && ((^DAT_O[15:8])  !== 1'b1))) ||
                (SEL_O[2] && (((^DAT_O[23:16]) !== 1'b0) && ((^DAT_O[23:16]) !== 1'b1))) ||
                (SEL_O[3] && (((^DAT_O[31:24]) !== 1'b0) && ((^DAT_O[31:24]) !== 1'b1)))
               )
            begin
                $display("*E (%0t) Master provided invalid data during write and qualified it with STB_O", $time) ;
                $fdisplay(log_file_desc, "*E (%0t)(%m)Master provided invalid data during write and qualified it with STB_O", $time) ;
                $display("*E (%0t) Byte select value: SEL_O = %b, Data bus value: DAT_O =  %h ", $time, SEL_O, DAT_O) ;
                $fdisplay(log_file_desc, "*E (%0t)(%m)Byte select value: SEL_O = %b, Data bus value: DAT_O =  %h ", $time, SEL_O, DAT_O) ;
            end

        end
        else
        if (~WE_O && ACK_I)
        begin
            if (
                (SEL_O[0] && (((^DAT_I[7:0])   !== 1'b0) && ((^DAT_I[7:0])   !== 1'b1))) ||
                (SEL_O[1] && (((^DAT_I[15:8])  !== 1'b0) && ((^DAT_I[15:8])  !== 1'b1))) ||
                (SEL_O[2] && (((^DAT_I[23:16]) !== 1'b0) && ((^DAT_I[23:16]) !== 1'b1))) ||
                (SEL_O[3] && (((^DAT_I[31:24]) !== 1'b0) && ((^DAT_I[31:24]) !== 1'b1)))
               )
            begin
                $display("*E (%0t) Slave provided invalid data during read and qualified it with ACK_I", $time) ;
                $fdisplay(log_file_desc, "*E (%0t)(%m)Slave provided invalid data during read and qualified it with ACK_I", $time) ;
                $display("*E (%0t) Byte select value: SEL_O = %b, Data bus value: DAT_I =  %h ", $time, SEL_O, DAT_I) ;
                $fdisplay(log_file_desc, "*E (%0t)(%m)Byte select value: SEL_O = %b, Data bus value: DAT_I =  %h ", $time, SEL_O, DAT_I) ;
            end
        end
    end
end

initial
begin
    previous_data = 0 ;
    previous_address = 0 ;
    can_change = 1 ;
end
endmodule // BUS_MON