// ========== Copyright Header Begin ==========================================
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// ========== Copyright Header Begin ==========================================
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//
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//
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// OpenSPARC T1 Processor File: sparc_exu_rndrob.v
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// OpenSPARC T1 Processor File: sparc_exu_rndrob.v
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// Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
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// Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
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// DO NOT ALTER OR REMOVE COPYRIGHT NOTICES.
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// DO NOT ALTER OR REMOVE COPYRIGHT NOTICES.
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//
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//
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// The above named program is free software; you can redistribute it and/or
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// The above named program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public
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// modify it under the terms of the GNU General Public
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// License version 2 as published by the Free Software Foundation.
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// License version 2 as published by the Free Software Foundation.
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//
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//
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// The above named program is distributed in the hope that it will be
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// The above named program is distributed in the hope that it will be
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// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
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// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// General Public License for more details.
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// General Public License for more details.
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//
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//
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// You should have received a copy of the GNU General Public
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// You should have received a copy of the GNU General Public
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// License along with this work; if not, write to the Free Software
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// License along with this work; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
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// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
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//
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//
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// ========== Copyright Header End ============================================
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// ========== Copyright Header End ============================================
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`ifdef SIMPLY_RISC_TWEAKS
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`define SIMPLY_RISC_SCANIN .si(0)
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`else
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`define SIMPLY_RISC_SCANIN .si()
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`endif
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////////////////////////////////////////////////////////////////////////
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////////////////////////////////////////////////////////////////////////
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/*
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/*
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// Module Name: sparc_exu_rndrob
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// Module Name: sparc_exu_rndrob
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// Description:
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// Description:
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// Round robin scheduler. Least priority to the last granted
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// Round robin scheduler. Least priority to the last granted
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// customer. If no requests, the priority remains the same.
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// customer. If no requests, the priority remains the same.
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*/
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*/
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////////////////////////////////////////////////////////////////////////
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////////////////////////////////////////////////////////////////////////
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module sparc_exu_rndrob(/*AUTOARG*/
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module sparc_exu_rndrob(/*AUTOARG*/
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// Outputs
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// Outputs
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grant_vec,
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grant_vec,
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// Inputs
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// Inputs
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clk, reset, se, req_vec, advance
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clk, reset, se, req_vec, advance
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);
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);
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input clk, reset, se;
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input clk, reset, se;
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input [3:0] req_vec;
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input [3:0] req_vec;
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input advance;
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input advance;
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output [3:0] grant_vec;
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output [3:0] grant_vec;
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wire [3:0] pv,
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wire [3:0] pv,
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next_pv,
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next_pv,
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park_vec;
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park_vec;
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assign next_pv = advance ? grant_vec : park_vec;
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assign next_pv = advance ? grant_vec : park_vec;
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dffr #4 park_reg(.din (next_pv[3:0]),
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dffr_s #4 park_reg(.din (next_pv[3:0]),
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.clk (clk),
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.clk (clk),
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.q (pv[3:0]),
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.q (pv[3:0]),
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.rst (reset),
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.rst (reset),
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.se (se), .si(), .so());
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.se (se), `SIMPLY_RISC_SCANIN, .so());
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assign park_vec = pv;
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assign park_vec = pv;
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// if noone requests, don't advance, otherwise we'll go back to 0
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// if noone requests, don't advance, otherwise we'll go back to 0
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// and will not be fair to other requestors
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// and will not be fair to other requestors
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assign grant_vec[0] = park_vec[3] & req_vec[0] |
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assign grant_vec[0] = park_vec[3] & req_vec[0] |
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park_vec[2] & ~req_vec[3] & req_vec[0] |
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park_vec[2] & ~req_vec[3] & req_vec[0] |
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park_vec[1] & ~req_vec[2] & ~req_vec[3] & req_vec[0] |
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park_vec[1] & ~req_vec[2] & ~req_vec[3] & req_vec[0] |
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~req_vec[1] & ~req_vec[2] & ~req_vec[3];
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~req_vec[1] & ~req_vec[2] & ~req_vec[3];
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assign grant_vec[1] = park_vec[0] & req_vec[1] |
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assign grant_vec[1] = park_vec[0] & req_vec[1] |
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park_vec[3] & ~req_vec[0] & req_vec[1] |
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park_vec[3] & ~req_vec[0] & req_vec[1] |
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park_vec[2] & ~req_vec[3] & ~req_vec[0] & req_vec[1] |
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park_vec[2] & ~req_vec[3] & ~req_vec[0] & req_vec[1] |
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req_vec[1] & ~req_vec[2] & ~req_vec[3] & ~req_vec[0];
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req_vec[1] & ~req_vec[2] & ~req_vec[3] & ~req_vec[0];
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assign grant_vec[2] = park_vec[1] & req_vec[2] |
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assign grant_vec[2] = park_vec[1] & req_vec[2] |
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park_vec[0] & ~req_vec[1] & req_vec[2] |
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park_vec[0] & ~req_vec[1] & req_vec[2] |
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park_vec[3] & ~req_vec[0] & ~req_vec[1] & req_vec[2] |
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park_vec[3] & ~req_vec[0] & ~req_vec[1] & req_vec[2] |
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req_vec[2] & ~req_vec[3] & ~req_vec[0] & ~req_vec[1];
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req_vec[2] & ~req_vec[3] & ~req_vec[0] & ~req_vec[1];
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assign grant_vec[3] = park_vec[2] & req_vec[3] |
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assign grant_vec[3] = park_vec[2] & req_vec[3] |
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park_vec[1] & ~req_vec[2] & req_vec[3] |
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park_vec[1] & ~req_vec[2] & req_vec[3] |
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park_vec[0] & ~req_vec[1] & ~req_vec[2] & req_vec[3] |
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park_vec[0] & ~req_vec[1] & ~req_vec[2] & req_vec[3] |
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req_vec[3] & ~req_vec[0] & ~req_vec[1] & ~req_vec[2];
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req_vec[3] & ~req_vec[0] & ~req_vec[1] & ~req_vec[2];
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endmodule // sparc_exu_rndrob
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endmodule // sparc_exu_rndrob
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