// SPDX-FileCopyrightText: 2020 Efabless Corporation
//
// 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.
// SPDX-License-Identifier: Apache-2.0

`default_nettype none
/*
    Building blocks for DFF based RAM compiler for SKY130A 
    BYTE        :   8 memory cells used as a building block for WORD module
    WORD        :   32-bit memory word with select and byte-level WE
    DEC6x64     :   2x4 Binary Decoder
    DEC6x64     :   6x64 Binary decoder
    MUX4x1_32   :   32-bit 4x1 MUX
    MUX2x1_32   :   32-bit 2x1 MUX
    SRAM64x32   :   Tri-state buffers based 64x32 DFF RAM 
    DFFRAM_COL4 :   A single column of 4 SRAM64x32 blocks using 4x1 multiplexors
*/
/*
    Author: Mohamed Shalan (mshalan@aucegypt.edu)
*/

module BYTE (
`ifdef USE_POWER_PINS
    input VPWR,
    input VGND,
`endif
    input CLK,
    input WE,
    input SEL,
    input [7:0] Di,
    output [7:0] Do
);

    wire [7:0]  q_wire;
    wire        we_wire;
    wire        SEL_B;
    wire        GCLK;

    sky130_fd_sc_hd__inv_1 INV(
     `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .Y(SEL_B),
        .A(SEL)
    );

    sky130_fd_sc_hd__and2_1 CGAND( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .A(SEL),
        .B(WE),
        .X(we_wire)
    );

    sky130_fd_sc_hd__dlclkp_1 CG( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .CLK(CLK),
        .GCLK(GCLK),
        .GATE(we_wire) 
    );

    generate 
        genvar i;
        for(i=0; i<8; i=i+1) begin : BIT
            sky130_fd_sc_hd__dfxtp_1 FF (
            `ifdef USE_POWER_PINS
                .VPWR(VPWR),
                .VGND(VGND),
                .VPB(VPWR),
                .VNB(VGND),
            `endif 
                .D(Di[i]),
                .Q(q_wire[i]),
                .CLK(GCLK)
            );

            sky130_fd_sc_hd__ebufn_2 OBUF ( 
            `ifdef USE_POWER_PINS
                .VPWR(VPWR),
                .VGND(VGND),
                .VPB(VPWR),
                .VNB(VGND),
            `endif
                .A(q_wire[i]),
                .Z(Do[i]),
                .TE_B(SEL_B)
            );

        end
    endgenerate 

endmodule


module WORD32 (
`ifdef USE_POWER_PINS
    input VPWR,
    input VGND,
`endif
    input CLK,
    input [3:0] WE,
    input SEL,
    input [31:0] Di,
    output [31:0] Do
);

    BYTE B0 (
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
    `endif 
        .CLK(CLK), .WE(WE[0]), .SEL(SEL), .Di(Di[7:0]), .Do(Do[7:0]) );
    
    BYTE B1 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR), 
        .VGND(VGND),
    `endif
        .CLK(CLK), .WE(WE[1]), .SEL(SEL), .Di(Di[15:8]), .Do(Do[15:8]) );
    
    BYTE B2 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
    `endif
        .CLK(CLK), .WE(WE[2]), .SEL(SEL), .Di(Di[23:16]), .Do(Do[23:16]) );
    
    BYTE B3 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
    `endif
        .CLK(CLK), .WE(WE[3]), .SEL(SEL), .Di(Di[31:24]), .Do(Do[31:24]) );
    
endmodule 

module DEC1x2 (
`ifdef USE_POWER_PINS
    input VPWR,
    input VGND,
`endif
    input           EN,
    input   [0:0]   A,
    output  [1:0]   SEL
);
    sky130_fd_sc_hd__and2b_2    AND1 ( 
     `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(SEL[0]),
        .A_N(A),
        .B(EN)
    );

    sky130_fd_sc_hd__and2_2     AND3 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(SEL[1]),
        .A(A),
        .B(A[0])
    );
    
endmodule

module DEC2x4 (
`ifdef USE_POWER_PINS
    input VPWR,
    input VGND,
`endif
    input           EN,
    input   [1:0]   A,
    output  [3:0]   SEL
);
    sky130_fd_sc_hd__nor3b_4    AND0 ( 
     `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .Y(SEL[0]),
        .A(A[0]),
        .B(A[1]),
        .C_N(EN)
    );

    sky130_fd_sc_hd__and3b_4    AND1 (
     `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif 
        .X(SEL[1]),
        .A_N(A[1]),
        .B(A[0]),
        .C(EN) 
    );

    sky130_fd_sc_hd__and3b_4    AND2 ( 
     `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(SEL[2]),
        .A_N(A[0]),
        .B(A[1]),
        .C(EN)
    );
   
    sky130_fd_sc_hd__and3_4     AND3 ( 
     `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(SEL[3]),
        .A(A[1]),
        .B(A[0]),
        .C(EN) 
    );
    
endmodule

module DEC3x8 (
`ifdef USE_POWER_PINS
    input VPWR,
    input VGND,
`endif
    input           EN,
    input [2:0]     A,
    output [7:0]    SEL
);
    sky130_fd_sc_hd__nor4b_2   AND0 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .Y(SEL[0]),
        .A(A[0]),
        .B(A[1]),
        .C(A[2]),
        .D_N(EN)
    ); // 000

    sky130_fd_sc_hd__and4bb_2   AND1 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(SEL[1]),
        .A_N(A[2]),
        .B_N(A[1]),
        .C(A[0]),
        .D(EN)
    ); // 001

    sky130_fd_sc_hd__and4bb_2   AND2 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(SEL[2]),
        .A_N(A[2]),
        .B_N(A[0]),
        .C(A[1]),
        .D(EN) 
    ); // 010

    sky130_fd_sc_hd__and4b_2    AND3 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(SEL[3]),
        .A_N(A[2]),
        .B(A[1]),
        .C(A[0]),
        .D(EN) 
    );   // 011

    sky130_fd_sc_hd__and4bb_2   AND4 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(SEL[4]),
        .A_N(A[0]),
        .B_N(A[1]),
        .C(A[2]),
        .D(EN) 
    ); // 100

    sky130_fd_sc_hd__and4b_2    AND5 ( 
     `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(SEL[5]),
        .A_N(A[1]),
        .B(A[0]),
        .C(A[2]),
        .D(EN)
    );   // 101

    sky130_fd_sc_hd__and4b_2    AND6 ( 
     `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(SEL[6]),
        .A_N(A[0]),
        .B(A[1]), 
        .C(A[2]),
        .D(EN) 
    );   // 110

    sky130_fd_sc_hd__and4_2     AND7 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(SEL[7]),
        .A(A[0]),
        .B(A[1]),
        .C(A[2]), 
        .D(EN)
    ); // 111
endmodule


module DEC6x64 (
`ifdef USE_POWER_PINS
    input VPWR,
    input VGND,
`endif
    input           EN,
    input   [5:0]   A,
    output  [63:0] SEL
);
    wire [7:0] SEL0_w ;
    wire [2:0] A_buf;
    
    DEC3x8 DEC_L0 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
    `endif
        .EN(EN),
        .A(A[5:3]),
        .SEL(SEL0_w)
    );

    sky130_fd_sc_hd__clkbuf_16 ABUF[2:0] (
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(A_buf),
        .A(A[2:0])
    );

    generate
        genvar i;
        for(i=0; i<8; i=i+1) begin : DEC_L1
            DEC3x8 U ( 
            `ifdef USE_POWER_PINS
                .VPWR(VPWR),
                .VGND(VGND),
            `endif
                .EN(SEL0_w[i]),
                .A(A_buf),
                .SEL(SEL[7+8*i: 8*i])
            );
        end
    endgenerate
endmodule

module MUX2x1_32(
`ifdef USE_POWER_PINS
    input VPWR,
    input VGND,
`endif
    input   [31:0]      A0, A1,
    input   [0:0]       S,
    output  [31:0]      X
);
    sky130_fd_sc_hd__mux2_1 MUX[31:0] (
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .A0(A0),
        .A1(A1),
        .S(S[0]),
        .X(X)
    );

endmodule

module MUX4x1_32(
`ifdef USE_POWER_PINS
    input VPWR,
    input VGND,
`endif
    input   [31:0]      A0, A1, A2, A3,
    input   [1:0]       S,
    output  [31:0]      X
);
    sky130_fd_sc_hd__mux4_1 MUX[31:0] (
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .A0(A0), 
        .A1(A1),
        .A2(A2),
        .A3(A3),
        .S0(S[0]),
        .S1(S[1]),
        .X(X)
    );
endmodule

module PASS (
`ifdef USE_POWER_PINS
    input VPWR,
    input VGND,
`endif
    input [31:0] A,
    output [31:0] X
);
    assign X = A;
endmodule

module SRAM64x32(
`ifdef USE_POWER_PINS
    input VPWR,
    input VGND,
`endif
    input CLK,
    input [3:0] WE,
    input EN,
    input [31:0] Di,
    output [31:0] Do,
    input [5:0] A
);

    wire [63:0]     SEL;
    wire [31:0]     Do_pre;
    wire [31:0]     Di_buf;
    wire            CLK_buf;
    wire [3:0]      WE_buf;

    sky130_fd_sc_hd__clkbuf_16 CLKBUF (
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(CLK_buf),
        .A(CLK)
    );
    
    sky130_fd_sc_hd__clkbuf_16 WEBUF[3:0] (
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(WE_buf),
        .A(WE)
    );

    sky130_fd_sc_hd__clkbuf_16 DIBUF[31:0] (
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(Di_buf),
        .A(Di)
    );

    DEC6x64 DEC  ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
    `endif
        .EN(EN),
        .A(A),
        .SEL(SEL)
    );

    generate
        genvar i;
        for (i=0; i< 64; i=i+1) begin : WORD
            WORD32 W ( 
            `ifdef USE_POWER_PINS
                .VPWR(VPWR),
                .VGND(VGND),
            `endif
                .CLK(CLK_buf),
                .WE(WE_buf),
                .SEL(SEL[i]),
                .Di(Di_buf),
                .Do(Do_pre)
            );
        end
    endgenerate

    // Ensure that the Do_pre lines are not floating when EN = 0
    wire lo;
    wire float_buf_en;
    sky130_fd_sc_hd__clkbuf_4 FBUFENBUF( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(float_buf_en),
        .A(EN)
    );

    sky130_fd_sc_hd__conb_1 TIE (
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .LO(lo),
        .HI()
    );

    sky130_fd_sc_hd__ebufn_4 FLOATBUF[31:0] ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .A( lo ),
        .Z(Do_pre),
        .TE_B(float_buf_en)
    );

    generate 
        //genvar i;
        for(i=0; i<32; i=i+1) begin : OUT
            sky130_fd_sc_hd__dfxtp_1 FF ( 
            `ifdef USE_POWER_PINS
                .VPWR(VPWR),
                .VGND(VGND),
                .VPB(VPWR),
                .VNB(VGND),
            `endif
                .D(Do_pre[i]),
                .Q(Do[i]),
                .CLK(CLK)
            );
        end
    endgenerate 

endmodule

module DFFRAM_COL4 
(
`ifdef USE_POWER_PINS
    VPWR,
    VGND,
`endif
    CLK,
    WE,
    EN,
    Di,
    Do,
    A
);

    input           CLK;
    input   [3:0]   WE;
    input           EN;
    input   [31:0]  Di;
    output  [31:0]  Do;
    input   [7:0]   A;

`ifdef USE_POWER_PINS
    input VPWR;
    input VGND;
`endif

    wire [31:0]     Di_buf;
    wire [31:0]     Do_pre;
    wire            CLK_buf;
    wire [3:0]      WE_buf;
    wire [5:3]      A_buf;

    wire [31:0]     Do_B_0_0;
    wire [31:0]     Do_B_0_1;
    wire [31:0]     Do_B_0_2;
    wire [31:0]     Do_B_0_3;

    wire [3:0]      row_sel;

    sky130_fd_sc_hd__clkbuf_8 CLKBUF (
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(CLK_buf),
        .A(CLK)
    );

    sky130_fd_sc_hd__clkbuf_8 WEBUF[3:0] (
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(WE_buf),
        .A(WE)
    );

    sky130_fd_sc_hd__clkbuf_8 DIBUF[31:0] (
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(Di_buf), 
        .A(Di)
    );

    sky130_fd_sc_hd__clkbuf_16 ABUF[2:0] ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
        .VPB(VPWR),
        .VNB(VGND),
    `endif
        .X(A_buf),
        .A(A[5:3])
    );
    
    DEC2x4 DEC ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR), 
        .VGND(VGND),
    `endif
        .EN(EN),
        .A(A[7:6]),
        .SEL(row_sel)
    );

    SRAM64x32 B_0_0 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
    `endif
        .CLK(CLK_buf),
        .WE(WE_buf),
        .EN(row_sel[0]),
        .Di(Di_buf),
        .Do(Do_B_0_0),
        .A({A_buf,A[2:0]})
    );

    SRAM64x32 B_0_1 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR), 
        .VGND(VGND),
    `endif
        .CLK(CLK_buf),
        .WE(WE_buf),
        .EN(row_sel[1]),
        .Di(Di_buf),
        .Do(Do_B_0_1),
        .A({A_buf,A[2:0]})
    );

    SRAM64x32 B_0_2 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
    `endif
        .CLK(CLK_buf),
        .WE(WE_buf),
        .EN(row_sel[2]),
        .Di(Di_buf),
        .Do(Do_B_0_2), 
        .A({A_buf,A[2:0]}) 
    );

    SRAM64x32 B_0_3 ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
    `endif
        .CLK(CLK_buf),
        .WE(WE_buf),
        .EN(row_sel[3]),
        .Di(Di_buf),
        .Do(Do_B_0_3),
        .A({A_buf,A[2:0]})
    );

    MUX4x1_32 MUX ( 
    `ifdef USE_POWER_PINS
        .VPWR(VPWR),
        .VGND(VGND),
    `endif
        .A0(Do_B_0_0),
        .A1(Do_B_0_1),
        .A2(Do_B_0_2),
        .A3(Do_B_0_3),
        .S(A[7:6]),
        .X(Do)
    );

endmodule