464 lines
17 KiB
Systemverilog
464 lines
17 KiB
Systemverilog
// SPDX-License-Identifier: Apache-2.0
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// Copyright 2019 Western Digital Corporation or its affiliates.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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module dec_ib_ctl
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import swerv_types::*;
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(
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input logic free_clk, // free clk
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input logic active_clk, // active clk if not halt / pause
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input logic dbg_cmd_valid, // valid dbg cmd
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input logic dbg_cmd_write, // dbg cmd is write
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input logic [1:0] dbg_cmd_type, // dbg type
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input logic [1:0] dbg_cmd_size, // 00 - 1B, 01 - 2B, 10 - 4B, 11 - reserved
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input logic [31:0] dbg_cmd_addr, // expand to 31:0
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input logic exu_flush_final, // all flush sources: primary/secondary alu's, trap
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input logic dec_ib0_valid_eff_d, // effective valid taking decode into account
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input logic dec_ib1_valid_eff_d,
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input br_pkt_t i0_brp, // i0 branch packet from aligner
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input br_pkt_t i1_brp,
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input logic ifu_i0_pc4, // i0 is 4B inst else 2B
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input logic ifu_i1_pc4,
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input logic ifu_i0_valid, // i0 valid from ifu
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input logic ifu_i1_valid,
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input logic ifu_i0_icaf, // i0 instruction access fault
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input logic ifu_i1_icaf,
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input logic ifu_i0_icaf_second, // i0 has access fault on second 2B of 4B inst
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input logic ifu_i1_icaf_second,
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input logic ifu_i0_perr, // i0 instruction parity error
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input logic ifu_i1_perr,
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input logic ifu_i0_sbecc, // i0 single-bit error
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input logic ifu_i1_sbecc,
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input logic ifu_i0_dbecc, // i0 double-bit error
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input logic ifu_i1_dbecc,
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input logic [31:0] ifu_i0_instr, // i0 instruction from the aligner
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input logic [31:0] ifu_i1_instr,
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input logic [31:1] ifu_i0_pc, // i0 pc from the aligner
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input logic [31:1] ifu_i1_pc,
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input logic dec_i0_decode_d, // i0 decode
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input logic dec_i1_decode_d,
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input logic rst_l, // test stuff
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input logic clk,
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output logic dec_ib3_valid_d, // ib3 valid
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output logic dec_ib2_valid_d, // ib2 valid
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output logic dec_ib1_valid_d, // ib1 valid
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output logic dec_ib0_valid_d, // ib0 valid
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output logic [31:0] dec_i0_instr_d, // i0 inst at decode
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output logic [31:0] dec_i1_instr_d, // i1 inst at decode
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output logic [31:1] dec_i0_pc_d, // i0 pc at decode
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output logic [31:1] dec_i1_pc_d,
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output logic dec_i0_pc4_d, // i0 is 4B inst else 2B
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output logic dec_i1_pc4_d,
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output br_pkt_t dec_i0_brp, // i0 branch packet at decode
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output br_pkt_t dec_i1_brp,
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output logic dec_i0_icaf_d, // i0 instruction access fault at decode
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output logic dec_i1_icaf_d,
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output logic dec_i0_icaf_second_d, // i0 instruction access fault on second 2B of 4B inst
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output logic dec_i0_perr_d, // i0 instruction parity error at decode
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output logic dec_i1_perr_d,
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output logic dec_i0_sbecc_d, // i0 single-bit error at decode
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output logic dec_i1_sbecc_d,
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output logic dec_i0_dbecc_d, // i0 double-bit error at decode
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output logic dec_i1_dbecc_d,
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output logic dec_debug_wdata_rs1_d, // put debug write data onto rs1 source: machine is halted
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output logic dec_debug_fence_d, // debug fence inst
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input logic [15:0] ifu_i0_cinst, // 16b compressed inst from aligner
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input logic [15:0] ifu_i1_cinst,
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output logic [15:0] dec_i0_cinst_d, // 16b compress inst at decode
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output logic [15:0] dec_i1_cinst_d,
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input logic scan_mode
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);
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`include "global.h"
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logic flush_final;
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logic [3:0] ibval_in, ibval;
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logic [31:0] ib3_in, ib2_in, ib1_in, ib0_in;
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logic [31:0] ib3, ib2, ib1, ib0;
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logic [36:0] pc3_in, pc2_in, pc1_in, pc0_in;
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logic [36:0] pc3, pc2, pc1, pc0;
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logic [15:0] cinst3_in, cinst2_in, cinst1_in, cinst0_in;
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logic [15:0] cinst3, cinst2, cinst1, cinst0;
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logic write_i1_ib3, write_i0_ib3;
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logic write_i1_ib2, write_i0_ib2;
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logic write_i1_ib1, write_i0_ib1;
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logic write_i0_ib0;
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logic shift2, shift1, shift0;
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logic shift_ib1_ib0, shift_ib2_ib1, shift_ib3_ib2;
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logic shift_ib2_ib0;
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logic shift_ib3_ib1;
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logic ifu_i0_val, ifu_i1_val;
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logic debug_valid;
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logic [4:0] dreg;
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logic [11:0] dcsr;
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logic [31:0] ib0_debug_in;
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// logic debug_read_mem;
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// logic debug_write_mem;
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logic debug_read;
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logic debug_write;
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logic debug_read_gpr;
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logic debug_write_gpr;
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logic debug_read_csr;
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logic debug_write_csr;
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rvdff #(1) flush_upperff (.*, .clk(free_clk), .din(exu_flush_final), .dout(flush_final));
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logic [3:0] ibvalid;
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logic [3:0] i0_wen;
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logic [3:1] i1_wen;
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logic [3:0] shift_ibval;
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logic [3:0] ibwrite;
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assign ibvalid[3:0] = ibval[3:0] | i0_wen[3:0] | {i1_wen[3:1],1'b0};
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assign ibval_in[3:0] = (({4{shift0}} & ibvalid[3:0]) |
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({4{shift1}} & {1'b0, ibvalid[3:1]}) |
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({4{shift2}} & {2'b0, ibvalid[3:2]})) & ~{4{flush_final}};
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rvdff #(4) ibvalff (.*, .clk(active_clk), .din(ibval_in[3:0]), .dout(ibval[3:0]));
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// only valid if there is room
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if (DEC_INSTBUF_DEPTH==4) begin
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assign ifu_i0_val = ifu_i0_valid & ~ibval[3] & ~flush_final;
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assign ifu_i1_val = ifu_i1_valid & ~ibval[2] & ~flush_final;
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end
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else begin
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assign ifu_i0_val = ifu_i0_valid & (~dec_ib0_valid_eff_d | ~dec_ib1_valid_eff_d) & ~flush_final;
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assign ifu_i1_val = ifu_i1_valid & (~dec_ib0_valid_eff_d & ~dec_ib1_valid_eff_d) & ~flush_final;
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end
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assign i0_wen[0] = ~ibval[0] & (ifu_i0_val | debug_valid);
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assign i0_wen[1] = ibval[0] & ~ibval[1] & ifu_i0_val;
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assign i0_wen[2] = ibval[1] & ~ibval[2] & ifu_i0_val;
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assign i0_wen[3] = ibval[2] & ~ibval[3] & ifu_i0_val;
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assign i1_wen[1] = ~ibval[0] & ifu_i1_val;
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assign i1_wen[2] = ibval[0] & ~ibval[1] & ifu_i1_val;
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assign i1_wen[3] = ibval[1] & ~ibval[2] & ifu_i1_val;
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// start trace
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if (DEC_INSTBUF_DEPTH==4) begin
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assign cinst3_in[15:0] = ({16{write_i0_ib3}} & ifu_i0_cinst[15:0]) |
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({16{write_i1_ib3}} & ifu_i1_cinst[15:0]);
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rvdffe #(16) cinst3ff (.*, .en(ibwrite[3]), .din(cinst3_in[15:0]), .dout(cinst3[15:0]));
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assign cinst2_in[15:0] = ({16{write_i0_ib2}} & ifu_i0_cinst[15:0]) |
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({16{write_i1_ib2}} & ifu_i1_cinst[15:0]) |
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({16{shift_ib3_ib2}} & cinst3[15:0]);
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rvdffe #(16) cinst2ff (.*, .en(ibwrite[2]), .din(cinst2_in[15:0]), .dout(cinst2[15:0]));
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end // if (DEC_INSTBUF_DEPTH==4)
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else begin
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assign cinst3 = '0;
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assign cinst2 = '0;
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end
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assign cinst1_in[15:0] = ({16{write_i0_ib1}} & ifu_i0_cinst[15:0]) |
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({16{write_i1_ib1}} & ifu_i1_cinst[15:0]) |
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({16{shift_ib2_ib1}} & cinst2[15:0]) |
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({16{shift_ib3_ib1}} & cinst3[15:0]);
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rvdffe #(16) cinst1ff (.*, .en(ibwrite[1]), .din(cinst1_in[15:0]), .dout(cinst1[15:0]));
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assign cinst0_in[15:0] = ({16{write_i0_ib0}} & ifu_i0_cinst[15:0]) |
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({16{shift_ib1_ib0}} & cinst1[15:0]) |
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({16{shift_ib2_ib0}} & cinst2[15:0]);
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rvdffe #(16) cinst0ff (.*, .en(ibwrite[0]), .din(cinst0_in[15:0]), .dout(cinst0[15:0]));
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assign dec_i0_cinst_d[15:0] = cinst0[15:0];
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assign dec_i1_cinst_d[15:0] = cinst1[15:0];
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// end trace
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// pc tracking
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assign ibwrite[3:0] = { write_i0_ib3 | write_i1_ib3,
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write_i0_ib2 | write_i1_ib2 | shift_ib3_ib2,
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write_i0_ib1 | write_i1_ib1 | shift_ib2_ib1 | shift_ib3_ib1,
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write_i0_ib0 | shift_ib1_ib0 | shift_ib2_ib0
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};
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logic [36:0] ifu_i1_pcdata, ifu_i0_pcdata;
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assign ifu_i1_pcdata[36:0] = { ifu_i1_icaf_second, ifu_i1_dbecc, ifu_i1_sbecc, ifu_i1_perr, ifu_i1_icaf,
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ifu_i1_pc[31:1], ifu_i1_pc4 };
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assign ifu_i0_pcdata[36:0] = { ifu_i0_icaf_second, ifu_i0_dbecc, ifu_i0_sbecc, ifu_i0_perr, ifu_i0_icaf,
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ifu_i0_pc[31:1], ifu_i0_pc4 };
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if (DEC_INSTBUF_DEPTH==4) begin
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assign pc3_in[36:0] = ({37{write_i0_ib3}} & ifu_i0_pcdata[36:0]) |
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({37{write_i1_ib3}} & ifu_i1_pcdata[36:0]);
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rvdffe #(37) pc3ff (.*, .en(ibwrite[3]), .din(pc3_in[36:0]), .dout(pc3[36:0]));
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assign pc2_in[36:0] = ({37{write_i0_ib2}} & ifu_i0_pcdata[36:0]) |
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({37{write_i1_ib2}} & ifu_i1_pcdata[36:0]) |
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({37{shift_ib3_ib2}} & pc3[36:0]);
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rvdffe #(37) pc2ff (.*, .en(ibwrite[2]), .din(pc2_in[36:0]), .dout(pc2[36:0]));
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end // if (DEC_INSTBUF_DEPTH==4)
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else begin
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assign pc3 = '0;
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assign pc2 = '0;
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end
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assign pc1_in[36:0] = ({37{write_i0_ib1}} & ifu_i0_pcdata[36:0]) |
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({37{write_i1_ib1}} & ifu_i1_pcdata[36:0]) |
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({37{shift_ib2_ib1}} & pc2[36:0]) |
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({37{shift_ib3_ib1}} & pc3[36:0]);
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rvdffe #(37) pc1ff (.*, .en(ibwrite[1]), .din(pc1_in[36:0]), .dout(pc1[36:0]));
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assign pc0_in[36:0] = ({37{write_i0_ib0}} & ifu_i0_pcdata[36:0]) |
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({37{shift_ib1_ib0}} & pc1[36:0]) |
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({37{shift_ib2_ib0}} & pc2[36:0]);
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rvdffe #(37) pc0ff (.*, .en(ibwrite[0]), .din(pc0_in[36:0]), .dout(pc0[36:0]));
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assign dec_i0_icaf_second_d = pc0[36]; // icaf's can only decode as i0
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assign dec_i1_dbecc_d = pc1[35];
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assign dec_i0_dbecc_d = pc0[35];
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assign dec_i1_sbecc_d = pc1[34];
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assign dec_i0_sbecc_d = pc0[34];
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assign dec_i1_perr_d = pc1[33];
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assign dec_i0_perr_d = pc0[33];
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assign dec_i1_icaf_d = pc1[32];
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assign dec_i0_icaf_d = pc0[32];
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assign dec_i1_pc_d[31:1] = pc1[31:1];
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assign dec_i0_pc_d[31:1] = pc0[31:1];
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assign dec_i1_pc4_d = pc1[0];
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assign dec_i0_pc4_d = pc0[0];
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// branch prediction
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logic [$bits(br_pkt_t)-1:0] bp3_in,bp3,bp2_in,bp2,bp1_in,bp1,bp0_in,bp0;
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if (DEC_INSTBUF_DEPTH==4) begin
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assign bp3_in = ({$bits(br_pkt_t){write_i0_ib3}} & i0_brp) |
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({$bits(br_pkt_t){write_i1_ib3}} & i1_brp);
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rvdffe #($bits(br_pkt_t)) bp3ff (.*, .en(ibwrite[3]), .din(bp3_in), .dout(bp3));
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assign bp2_in = ({$bits(br_pkt_t){write_i0_ib2}} & i0_brp) |
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({$bits(br_pkt_t){write_i1_ib2}} & i1_brp) |
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({$bits(br_pkt_t){shift_ib3_ib2}} & bp3);
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rvdffe #($bits(br_pkt_t)) bp2ff (.*, .en(ibwrite[2]), .din(bp2_in), .dout(bp2));
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end // if (DEC_INSTBUF_DEPTH==4)
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else begin
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assign bp3 = '0;
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assign bp2 = '0;
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end
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assign bp1_in = ({$bits(br_pkt_t){write_i0_ib1}} & i0_brp) |
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({$bits(br_pkt_t){write_i1_ib1}} & i1_brp) |
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({$bits(br_pkt_t){shift_ib2_ib1}} & bp2) |
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({$bits(br_pkt_t){shift_ib3_ib1}} & bp3);
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rvdffe #($bits(br_pkt_t)) bp1ff (.*, .en(ibwrite[1]), .din(bp1_in), .dout(bp1));
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assign bp0_in = ({$bits(br_pkt_t){write_i0_ib0}} & i0_brp) |
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({$bits(br_pkt_t){shift_ib1_ib0}} & bp1) |
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({$bits(br_pkt_t){shift_ib2_ib0}} & bp2);
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rvdffe #($bits(br_pkt_t)) bp0ff (.*, .en(ibwrite[0]), .din(bp0_in), .dout(bp0));
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// instruction buffers
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if (DEC_INSTBUF_DEPTH==4) begin
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assign ib3_in[31:0] = ({32{write_i0_ib3}} & ifu_i0_instr[31:0]) |
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({32{write_i1_ib3}} & ifu_i1_instr[31:0]);
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rvdffe #(32) ib3ff (.*, .en(ibwrite[3]), .din(ib3_in[31:0]), .dout(ib3[31:0]));
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assign ib2_in[31:0] = ({32{write_i0_ib2}} & ifu_i0_instr[31:0]) |
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({32{write_i1_ib2}} & ifu_i1_instr[31:0]) |
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({32{shift_ib3_ib2}} & ib3[31:0]);
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rvdffe #(32) ib2ff (.*, .en(ibwrite[2]), .din(ib2_in[31:0]), .dout(ib2[31:0]));
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end // if (DEC_INSTBUF_DEPTH==4)
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else begin
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assign ib3 = '0;
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assign ib2 = '0;
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end
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assign ib1_in[31:0] = ({32{write_i0_ib1}} & ifu_i0_instr[31:0]) |
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({32{write_i1_ib1}} & ifu_i1_instr[31:0]) |
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({32{shift_ib2_ib1}} & ib2[31:0]) |
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({32{shift_ib3_ib1}} & ib3[31:0]);
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rvdffe #(32) ib1ff (.*, .en(ibwrite[1]), .din(ib1_in[31:0]), .dout(ib1[31:0]));
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// GPR accesses
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// put reg to read on rs1
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// read -> or %x0, %reg,%x0 {000000000000,reg[4:0],110000000110011}
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// put write date on rs1
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// write -> or %reg, %x0, %x0 {00000000000000000110,reg[4:0],0110011}
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// CSR accesses
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// csr is of form rd, csr, rs1
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// read -> csrrs %x0, %csr, %x0 {csr[11:0],00000010000001110011}
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// put write data on rs1
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// write -> csrrw %x0, %csr, %x0 {csr[11:0],00000001000001110011}
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// abstract memory command not done here
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assign debug_valid = dbg_cmd_valid & (dbg_cmd_type[1:0] != 2'h2);
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assign debug_read = debug_valid & ~dbg_cmd_write;
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assign debug_write = debug_valid & dbg_cmd_write;
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assign debug_read_gpr = debug_read & (dbg_cmd_type[1:0]==2'h0);
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assign debug_write_gpr = debug_write & (dbg_cmd_type[1:0]==2'h0);
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assign debug_read_csr = debug_read & (dbg_cmd_type[1:0]==2'h1);
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assign debug_write_csr = debug_write & (dbg_cmd_type[1:0]==2'h1);
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assign dreg[4:0] = dbg_cmd_addr[4:0];
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assign dcsr[11:0] = dbg_cmd_addr[11:0];
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assign ib0_debug_in[31:0] = ({32{debug_read_gpr}} & {12'b000000000000,dreg[4:0],15'b110000000110011}) |
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({32{debug_write_gpr}} & {20'b00000000000000000110,dreg[4:0],7'b0110011}) |
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({32{debug_read_csr}} & {dcsr[11:0],20'b00000010000001110011}) |
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({32{debug_write_csr}} & {dcsr[11:0],20'b00000001000001110011});
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// machine is in halted state, pipe empty, write will always happen next cycle
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rvdff #(1) debug_wdata_rs1ff (.*, .clk(free_clk), .din(debug_write_gpr | debug_write_csr), .dout(dec_debug_wdata_rs1_d));
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// special fence csr for use only in debug mode
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logic debug_fence_in;
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assign debug_fence_in = debug_write_csr & (dcsr[11:0] == 12'h7c4);
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rvdff #(1) debug_fence_ff (.*, .clk(free_clk), .din(debug_fence_in), .dout(dec_debug_fence_d));
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assign ib0_in[31:0] = ({32{write_i0_ib0}} & ((debug_valid) ? ib0_debug_in[31:0] : ifu_i0_instr[31:0])) |
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({32{shift_ib1_ib0}} & ib1[31:0]) |
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({32{shift_ib2_ib0}} & ib2[31:0]);
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rvdffe #(32) ib0ff (.*, .en(ibwrite[0]), .din(ib0_in[31:0]), .dout(ib0[31:0]));
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assign dec_ib3_valid_d = ibval[3];
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assign dec_ib2_valid_d = ibval[2];
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assign dec_ib1_valid_d = ibval[1];
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assign dec_ib0_valid_d = ibval[0];
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assign dec_i0_instr_d[31:0] = ib0[31:0];
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assign dec_i1_instr_d[31:0] = ib1[31:0];
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assign dec_i0_brp = bp0;
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assign dec_i1_brp = bp1;
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assign shift1 = dec_i0_decode_d & ~dec_i1_decode_d;
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assign shift2 = dec_i0_decode_d & dec_i1_decode_d;
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assign shift0 = ~dec_i0_decode_d;
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// compute shifted ib valids to determine where to write
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assign shift_ibval[3:0] = ({4{shift1}} & {1'b0, ibval[3:1] }) |
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({4{shift2}} & {2'b0, ibval[3:2]}) |
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({4{shift0}} & ibval[3:0]);
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assign write_i0_ib0 = ~shift_ibval[0] & (ifu_i0_val | debug_valid);
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assign write_i0_ib1 = shift_ibval[0] & ~shift_ibval[1] & ifu_i0_val;
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assign write_i0_ib2 = shift_ibval[1] & ~shift_ibval[2] & ifu_i0_val;
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assign write_i0_ib3 = shift_ibval[2] & ~shift_ibval[3] & ifu_i0_val;
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assign write_i1_ib1 = ~shift_ibval[0] & ifu_i1_val;
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assign write_i1_ib2 = shift_ibval[0] & ~shift_ibval[1] & ifu_i1_val;
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assign write_i1_ib3 = shift_ibval[1] & ~shift_ibval[2] & ifu_i1_val;
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assign shift_ib1_ib0 = shift1 & ibval[1];
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assign shift_ib2_ib1 = shift1 & ibval[2];
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assign shift_ib3_ib2 = shift1 & ibval[3];
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assign shift_ib2_ib0 = shift2 & ibval[2];
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assign shift_ib3_ib1 = shift2 & ibval[3];
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endmodule
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