lab-08: fix HiZ on register file when READ=0

Gate level implementation for the following components:
- DECODER_5x32
- MUX32_32x1
- REGISTER_FILE_32x32

Additional tests added in register file testbench.

TESTBENCH/register_file_tb.v

@@ -114,7 +114,6 @@ no_of_pass  = no_of_pass + 1;
 result[ridx] = DATA_R1; ridx=ridx+1;
 
 // TODO: Read and write from the same address at the same time?
-// TODO: Write when WRITE=0 should be tested
 
 #5    READ=1'b0; WRITE=1'b0; // No op
 

alu.v

@@ -44,7 +44,7 @@ wire [31:0] res,
 // can use oprn[1] or oprn[3] for SnA
 wire SnA;
 or (SnA, OPRN[1], OPRN[3]);
-RC_ADD_SUB_32 addsub(.Y(res_addsub), .CO(), .A(OP1), .B(OP2), .SnA(SnA));
+RC_ADD_SUB_32 addsub(.Y(res_addsub), .A(OP1), .B(OP2), .SnA(SnA));
 buf slt [31:0] (res_slt, {31'b0,res_addsub[31]});
 
 // shift_r = xx0100
@@ -54,7 +54,7 @@ buf slt [31:0] (res_slt, {31'b0,res_addsub[31]});
 SHIFT32 shift(res_shift, OP1, OP2, OPRN[0]);
 
 // mul = xx0011
-MULT32 mul(.LO(res_mul), .HI(), .A(OP1), .B(OP2));
+MULT32 mul(.LO(res_mul), .A(OP1), .B(OP2));
 
 // and = xx0110
 // or  = xx0111
@@ -63,12 +63,11 @@ AND32_2x1 and32(res_and, OP1, OP2);
 OR32_2x1 or32(res_or, OP1, OP2);
 NOR32_2x1 nor32(res_nor, OP1, OP2);
 
-MUX32_16x1 out(.Y(res), .S(OPRN[3:0]), .I0(),
+MUX32_16x1 out(.Y(res), .S(OPRN[3:0]),
                .I1(res_addsub), .I2(res_addsub), .I3(res_mul),
                .I4(res_shift),.I5(res_shift),
                .I6(res_and), .I7(res_or), .I8(res_nor),
-               .I9(res_slt),
+               .I9(res_slt)
-               .I10(), .I11(), .I12(), .I13(), .I14(), .I15()
 );
 
 // or bits of result for zero flag

data_path.v

@@ -29,149 +29,6 @@ input [`CTRL_WIDTH_INDEX_LIMIT:0]  CTRL;
 input CLK, RST;
 input [`DATA_INDEX_LIMIT:0] DATA_IN;
 
-wire pc_load, pc_sel_1, pc_sel_2, pc_sel_3,
+// TBD
-    ir_load, reg_r, reg_w,
-    r1_sel_1, wa_sel_1, wa_sel_2, wa_sel_3,
-
-    sp_load, op1_sel_1,
-    op2_sel_1, op2_sel_2, op2_sel_3, op2_sel_4,
-
-    wd_sel_1, wd_sel_2, wd_sel_3,
-    ma_sel_1, ma_sel_2,
-    md_sel_1;
-
-wire [5:0] alu_oprn;
-
-buf (pc_load, CTRL[0]);
-buf (pc_sel_1, CTRL[1]);
-buf (pc_sel_2, CTRL[2]);
-buf (pc_sel_3, CTRL[3]);
-
-buf (ir_load, CTRL[4]);
-buf (reg_r, CTRL[5]);
-buf (reg_w, CTRL[6]);
-
-buf (r1_sel_1, CTRL[7]);
-buf (wa_sel_1, CTRL[8]);
-buf (wa_sel_2, CTRL[9]);
-buf (wa_sel_3, CTRL[10]);
-
-buf (sp_load, CTRL[11]);
-buf (op1_sel_1, CTRL[12]);
-
-buf (op2_sel_1, CTRL[13]);
-buf (op2_sel_2, CTRL[14]);
-buf (op2_sel_3, CTRL[15]);
-buf (op2_sel_4, CTRL[16]);
-
-buf (wd_sel_1, CTRL[17]);
-buf (wd_sel_2, CTRL[18]);
-buf (wd_sel_3, CTRL[19]);
-
-buf (ma_sel_1, CTRL[20]);
-buf (ma_sel_2, CTRL[21]);
-
-buf (md_sel_1, CTRL[22]);
-
-buf alu_oprn_buf [5:0] (alu_oprn, CTRL[28:23]);
-
-// variables
-wire [31:0] ir; // Instruction Register
-wire [31:0] r1, r2; // Register File
-wire [31:0] pc, pc_inc; // Program Counter
-wire [31:0] sp; // Stack Pointer
-wire [31:0] alu_out; // ALU output
-
-// TODO: Why?
-buf ir_buf [31:0] (INSTRUCTION, ir);
-
-// Parse the instruction data
-wire [5:0]   opcode;
-wire [4:0]   rs;
-wire [4:0]   rt;
-wire [4:0]   rd;
-wire [4:0]   shamt;
-wire [5:0]   funct;
-wire [15:0]  imm;
-wire [25:0]  addr;
-
-// common for all
-buf opcode_buf [5:0] (opcode, ir[31:26]);
-// common for R-type, I-type
-buf rs_buf [4:0] (rs, ir[25:21]);
-buf rt_buf [4:0] (rt, ir[20:16]);
-// for R-type
-buf rd_buf [4:0] (rd, ir[15:11]);
-buf shamt_buf [4:0] (shamt, ir[10:6]);
-buf funct_buf [5:0] (funct, ir[5:0]);
-// for I-type
-buf imm_buf [15:0] (imm, ir[15:0]);
-// for J-type
-buf addr_buf [25:0] (addr, ir[25:0]);
-
-
-// Instruction Register input
-// Instruction Register
-REG32 ir_inst(.Q(ir), .D(DATA_IN), .LOAD(ir_load), .CLK(CLK), .RESET(RST));
-
-// Register File Input
-wire [31:0] r1_sel, wa_sel, wd_sel;
-wire [31:0] wa_sel_p1, wa_sel_p2, wd_sel_p1, wd_sel_p2;
-wire [31:0] imm_zx_lsb;
-buf imm_zx_lsb_buf [31:0] (imm_zx_lsb, {imm, 16'b0});
-MUX32_2x1 mux_r1_sel(r1_sel, {27'b0,rs}, 32'b0, r1_sel_1);
-MUX32_2x1 mux_wa_sel_p1(wa_sel_p1, {27'b0,rd}, {27'b0,rt}, wa_sel_1);
-// TODO: Why 31?
-MUX32_2x1 mux_wa_sel_p2(wa_sel_p2, 32'b0, 31, wa_sel_2);
-MUX32_2x1 mux_wa_sel(wa_sel, wa_sel_p2, wa_sel_p1, wa_sel_3);
-MUX32_2x1 mux_wd_sel_p1(wd_sel_p1, alu_out,DATA_IN, wd_sel_1);
-MUX32_2x1 mux_wd_sel_p2(wd_sel_p2, wd_sel_p1, imm_zx_lsb, wd_sel_2);
-MUX32_2x1 mux_wd_sel(wd_sel, pc_inc, wd_sel_p2, wd_sel_3);
-// Register File
-REGISTER_FILE_32x32 rf_inst(.DATA_R1(r1), .DATA_R2(r2), .ADDR_R1(r1_sel[4:0]), .ADDR_R2(rt),
-                            .DATA_W(wd_sel), .ADDR_W(wa_sel[4:0]), .READ(reg_r), .WRITE(reg_w), .CLK(CLK), .RST(RST));
-
-// ALU Input
-wire [31:0] op1_sel, op2_sel;
-wire [31:0] op2_sel_p1, op2_sel_p2, op2_sel_p3;
-wire [31:0] shamt_zx, imm_sx, imm_zx;
-buf shamt_zx_buf [31:0] (shamt_zx, {27'b0, shamt});
-buf imm_sx_buf [31:0] (imm_sx, {{16{imm[15]}}, imm});
-buf imm_zx_buf [31:0] (imm_zx, {16'b0, imm});
-MUX32_2x1 mux_op1_sel(op1_sel, r1, sp, op1_sel_1);
-MUX32_2x1 mux_op2_sel_p1(op2_sel_p1, 32'b1, shamt_zx, op2_sel_1);
-MUX32_2x1 mux_op2_sel_p2(op2_sel_p2, imm_zx, imm_sx, op2_sel_2);
-MUX32_2x1 mux_op2_sel_p3(op2_sel_p3, op2_sel_p2, op2_sel_p1, op2_sel_3);
-MUX32_2x1 mux_op2_sel(op2_sel, op2_sel_p3, r2, op2_sel_4);
-// ALU
-ALU alu_inst(.OUT(alu_out), .ZERO(ZERO), .OP1(op1_sel), .OP2(op2_sel), .OPRN(alu_oprn));
-
-// Progam Counter Input
-wire [31:0] pc_sel;
-wire [31:0] pc_offset, pc_jump, pc_sel_p1, pc_sel_p2;
-RC_ADD_SUB_32 pc_inc_inst(.Y(pc_inc), .CO(), .A(pc), .B(32'b1), .SnA(1'b0));
-MUX32_2x1 mux_pc_sel_p1(pc_sel_p1, r1, pc_inc, pc_sel_1);
-RC_ADD_SUB_32 pc_sel_2_inst(.Y(pc_offset), .CO(), .A(pc), .B(imm_sx), .SnA(1'b0));
-MUX32_2x1 mux_pc_sel_p2(pc_sel_p2, pc_sel_p1, pc_offset, pc_sel_2);
-buf pc_jump_buf [31:0] (pc_jump, {6'b0, addr});
-MUX32_2x1 mux_pc_sel(pc_sel, pc_jump, pc_sel_p2, pc_sel_3);
-// Program Counter
-defparam pc_inst.PATTERN = `INST_START_ADDR;
-REG32_PP pc_inst(.Q(pc), .D(pc_sel), .LOAD(pc_load), .CLK(CLK), .RESET(RST));
-
-// Stack Pointer
-defparam sp_inst.PATTERN = `INIT_STACK_POINTER;
-REG32_PP sp_inst(.Q(sp), .D(alu_out), .LOAD(sp_load), .CLK(CLK), .RESET(RST));
-
-// Data out
-MUX32_2x1 mux_data_out(DATA_OUT, r2, r1, md_sel_1);
-
-// Address out
-wire [31:0] ma_sel_p1;
-MUX32_2x1 mux_ma_sel_p1(ma_sel_p1, alu_out, sp, ma_sel_1);
-// TODO: Check address calculation since it's 26 bit
-(* keep="soft" *)
-wire [5:0] _addr_ignored;
-MUX32_2x1 mux_ma_sel({_addr_ignored,ADDR}, ma_sel_p1, pc, ma_sel_2);
 
 endmodule

logic.v

@@ -20,7 +20,7 @@ output [63:0] Y;
 //input list
 input [63:0] A;
 
-RC_ADD_SUB_64 twoscomp64_sub(.Y(Y), .CO(), .A(64'b0), .B(A), .SnA(1'b1));
+RC_ADD_SUB_64 twoscomp64_sub(.Y(Y), .A(64'b0), .B(A), .SnA(1'b1));
 
 endmodule
 
@@ -31,31 +31,7 @@ output [31:0] Y;
 //input list
 input [31:0] A;
 
-RC_ADD_SUB_32 twoscomp32_sub(.Y(Y), .CO(), .A(0), .B(A), .SnA(1'b1));
+RC_ADD_SUB_32 twoscomp32_sub(.Y(Y), .A(0), .B(A), .SnA(1'b1));
-
-endmodule
-
-// 32-bit register with parameterized preset pattern
-module REG32_PP(Q, D, LOAD, CLK, RESET);
-parameter PATTERN = 32'h00000000;
-output [31:0] Q;
-
-input CLK, LOAD;
-input [31:0] D;
-input RESET;
-
-wire [31:0] qbar;
-
-genvar i;
-generate
-    for(i=0; i<32; i=i+1)
-    begin : reg32_gen_loop
-       if (PATTERN[i] == 0)
-              REG1 reg_inst(.Q(Q[i]), .Qbar(qbar[i]), .D(D[i]), .L(LOAD), .C(CLK), .nP(1'b1), .nR(RESET));
-        else
-              REG1 reg_inst(.Q(Q[i]), .Qbar(qbar[i]), .D(D[i]), .L(LOAD), .C(CLK), .nP(RESET), .nR(1'b1));
-    end
-endgenerate
 
 endmodule
 

register_file.v

@@ -42,11 +42,8 @@ output [`DATA_INDEX_LIMIT:0] DATA_R1;
 output [`DATA_INDEX_LIMIT:0] DATA_R2;
 
 wire [31:0] Q [31:0];
-wire [31:0] r_write_sel, r_write;
+wire [31:0] r_write;
-DECODER_5x32 d_write(r_write_sel, ADDR_W);
+DECODER_5x32 d_write(r_write, ADDR_W);
-
-// only write when WRITE=1
-and write_active [31:0] (r_write, r_write_sel, WRITE);
 
 REG32 r[31:0] (Q, DATA_W, r_write, CLK, RST);