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// ========== Copyright Header Begin ==========================================

// 

// OpenSPARC T1 Processor File: sparc_exu_eclbyplog.v

// Copyright (c) 2006 Sun Microsystems, Inc.  All Rights Reserved.

// DO NOT ALTER OR REMOVE COPYRIGHT NOTICES.

// 

// The above named program is free software; you can redistribute it and/or

// modify it under the terms of the GNU General Public

// License version 2 as published by the Free Software Foundation.

// 

// The above named program is distributed in the hope that it will be 

// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

// General Public License for more details.

// 

// You should have received a copy of the GNU General Public

// License along with this work; if not, write to the Free Software

// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.

// 

// ========== Copyright Header End ============================================

////////////////////////////////////////////////////////////////////////

/*

//  Module Name: sparc_exu_eclbyplog

//      Description: This block implements the bypass logic for a single

//      operand.  It takes the destination registers of all

//      four forwarding sources and the rs.  It also has the

//      thread for the instruction in each stage and whether

//      the instruction writes to the register file.  It won't

//      bypass if rs =0.

*/

module sparc_exu_eclbyplog (/*AUTOARG*/

   // Outputs

   rs_sel_mux1_m, rs_sel_mux1_w, rs_sel_mux1_w2, rs_sel_mux1_other,

   rs_sel_mux2_usemux1, rs_sel_mux2_rf, rs_sel_mux2_e,

   rs_sel_mux2_ld, rs_sel_longmux_g2, rs_sel_longmux_w2,

   rs_sel_longmux_ldxa,

   // Inputs

   sehold, use_other, rs, rd_e, rd_m, ecl_irf_rd_w, ld_rd_g,

   wb_byplog_rd_w2, wb_byplog_rd_g2, tid_d, thr_match_de,

   thr_match_dm, ecl_irf_tid_w, ld_thr_match_dg, wb_byplog_tid_w2,

   ld_thr_match_dg2, ifu_exu_kill_e, wb_e, bypass_m,

   lsu_exu_dfill_vld_g, bypass_w, wb_byplog_wen_w2, wb_byplog_wen_g2,

   ecl_byp_ldxa_g

   ) ;

   input sehold;

   input use_other;

   input [4:0] rs;              // source register

   input [4:0] rd_e;            // destination regs for all stages

   input [4:0] rd_m;

   input [4:0] ecl_irf_rd_w;

   input [4:0] ld_rd_g;

   input [4:0] wb_byplog_rd_w2;

   input [4:0] wb_byplog_rd_g2;

   input [1:0] tid_d;

   input       thr_match_de;

   input       thr_match_dm;

   input [1:0] ecl_irf_tid_w;

   input       ld_thr_match_dg;

   input [1:0] wb_byplog_tid_w2;

   input       ld_thr_match_dg2;

   input       ifu_exu_kill_e;

   input       wb_e;            // whether each stage writes to reg

   input       bypass_m;            // file

   input       lsu_exu_dfill_vld_g;

   input       bypass_w;

   input       wb_byplog_wen_w2;

   input       wb_byplog_wen_g2;

   input       ecl_byp_ldxa_g;

   output      rs_sel_mux1_m;

   output      rs_sel_mux1_w;

   output      rs_sel_mux1_w2;

   output      rs_sel_mux1_other;

   output      rs_sel_mux2_usemux1;

   output      rs_sel_mux2_rf;

   output      rs_sel_mux2_e;

   output      rs_sel_mux2_ld;

   output      rs_sel_longmux_g2;

   output      rs_sel_longmux_w2;

   output      rs_sel_longmux_ldxa;

   wire        use_e, use_m, use_w, use_w2, use_rf, use_ld, use_ldxa;

   wire         match_e, match_m, match_w, match_w2, match_ld; // outputs of comparison

   wire         match_g2;

   wire         bypass;         // boolean that allows bypassing

   wire         rs_is_nonzero;

   // Don't bypass if rs == 0 or we are supposed to use other

   assign       rs_is_nonzero = rs[0]|rs[1]|rs[2]|rs[3]|rs[4];

   assign       bypass = rs_is_nonzero & ~use_other & ~sehold;

   // Normal pipe priority: E, M, W, RF

   // Ld priority: LD, RF

   // W2 priority: E, M, W2, RF

   assign       use_e = match_e & wb_e & ~ifu_exu_kill_e;

   assign       use_m = match_m & bypass_m & ~use_e;

   assign       use_w = match_w & bypass_w & ~use_m & ~use_e;

   assign       use_ld = match_ld & lsu_exu_dfill_vld_g & ~ecl_byp_ldxa_g;

   assign       use_ldxa = match_ld & ecl_byp_ldxa_g;

   assign       use_w2 = (match_w2 & wb_byplog_wen_w2 | match_g2 & wb_byplog_wen_g2) & ~use_e & ~use_m;

   assign       use_rf = ~use_w2 & ~use_w & ~use_m & ~use_e & ~use_ld & ~use_ldxa;

   // mux1[M, W, W2, OTHER(optional)]

   // mux2[mux1, RF, E, LD]

   assign       rs_sel_mux2_e = (use_e & bypass);

   assign       rs_sel_mux2_rf = ((use_rf | ~bypass) & ~(use_other & ~sehold));

   assign       rs_sel_mux2_ld = (use_ld & ~use_e & ~use_w & ~use_m & ~use_w2 & bypass);

   assign       rs_sel_mux2_usemux1 = (use_other & ~sehold) | (~rs_sel_mux1_other & ~use_e);

   assign rs_sel_mux1_other = ~((use_m | use_w | use_w2 | use_ldxa) & bypass);

   assign rs_sel_mux1_w2 = ((use_w2 | use_ldxa) & bypass);

   assign rs_sel_mux1_w = (use_w & ~use_w2 & ~use_ldxa & bypass);

   assign rs_sel_mux1_m = (use_m & ~use_w2 & ~use_ldxa & bypass);

   assign rs_sel_longmux_ldxa = use_ldxa;

   assign rs_sel_longmux_g2 = match_g2 & wb_byplog_wen_g2 & ~use_ldxa;

   assign rs_sel_longmux_w2 = ~use_ldxa & ~(match_g2 & wb_byplog_wen_g2);

   // Comparisons

   assign match_e = thr_match_de & (rs[4:0] == rd_e[4:0]);

//   sparc_exu_eclcomp7 e_comp7(.out(match_e), .in1({tid_d[1:0],rs[4:0]}),

//                              .in2({ecl_rml_tid_e[1:0],rd_e[4:0]}));

   assign match_m = thr_match_dm & (rs[4:0] == rd_m[4:0]);

//   sparc_exu_eclcomp7 m_comp7(.out(match_m), .in1({tid_d[1:0],rs[4:0]}),

//                              .in2({tid_m[1:0],rd_m[4:0]}));

   sparc_exu_eclcomp7 w_comp7(.out(match_w), .in1({tid_d[1:0],rs[4:0]}),

                              .in2({ecl_irf_tid_w[1:0],ecl_irf_rd_w[4:0]}));

   sparc_exu_eclcomp7 w2_comp7(.out(match_w2), .in1({tid_d[1:0],rs[4:0]}),

                               .in2({wb_byplog_tid_w2[1:0],wb_byplog_rd_w2[4:0]}));

   assign match_ld = ld_thr_match_dg & (rs[4:0] == ld_rd_g[4:0]);

   assign match_g2 = ld_thr_match_dg2 & (rs[4:0] == wb_byplog_rd_g2[4:0]);

/* -----\/----- EXCLUDED -----\/-----

   sparc_exu_eclcomp7 ld_comp7(.out(match_ld), .in1({tid_d[1:0],rs[4:0]}),

                               .in2({ld_tid_g[1:0],ld_rd_g[4:0]}));

   sparc_exu_eclcomp7 g2_comp7(.out(match_g2), .in1({tid_d[1:0],rs[4:0]}),

                               .in2({wb_byplog_tid_g2[1:0],wb_byplog_rd_g2[4:0]}));

 -----/\----- EXCLUDED -----/\----- */

endmodule // sparc_exu_eclbyplog