[6] | 1 | // ========== Copyright Header Begin ========================================== |
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| 2 | // |
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| 3 | // OpenSPARC T1 Processor File: sparc_ifu_rndrob.v |
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| 4 | // Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved. |
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| 5 | // DO NOT ALTER OR REMOVE COPYRIGHT NOTICES. |
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| 6 | // |
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| 7 | // The above named program is free software; you can redistribute it and/or |
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| 8 | // modify it under the terms of the GNU General Public |
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| 9 | // License version 2 as published by the Free Software Foundation. |
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| 10 | // |
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| 11 | // The above named program is distributed in the hope that it will be |
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| 12 | // useful, but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 14 | // General Public License for more details. |
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| 15 | // |
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| 16 | // You should have received a copy of the GNU General Public |
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| 17 | // License along with this work; if not, write to the Free Software |
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| 18 | // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. |
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| 19 | // |
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| 20 | // ========== Copyright Header End ============================================ |
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| 21 | //////////////////////////////////////////////////////////////////////// |
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| 22 | /* |
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| 23 | // Module Name: sparc_ifu_rndrob |
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| 24 | // Description: |
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| 25 | // Round robin scheduler. Least priority to the last granted |
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| 26 | // customer. If no requests, the priority remains the same. |
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| 27 | // |
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| 28 | */ |
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| 29 | //////////////////////////////////////////////////////////////////////// |
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| 30 | |
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| 31 | module sparc_ifu_rndrob(/*AUTOARG*/ |
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| 32 | // Outputs |
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| 33 | grant_vec, so, |
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| 34 | // Inputs |
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| 35 | clk, reset, se, si, req_vec, advance, rst_tri_enable |
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| 36 | ); |
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| 37 | |
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| 38 | input clk, reset, se, si; |
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| 39 | |
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| 40 | input [3:0] req_vec; |
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| 41 | |
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| 42 | input advance; |
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| 43 | input rst_tri_enable; |
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| 44 | |
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| 45 | output [3:0] grant_vec; |
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| 46 | |
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| 47 | output so; |
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| 48 | |
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| 49 | wire [3:0] next_pv, |
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| 50 | pv, |
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| 51 | gv, |
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| 52 | park_vec; |
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| 53 | |
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| 54 | |
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| 55 | assign pv = advance ? grant_vec : |
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| 56 | park_vec; |
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| 57 | |
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| 58 | assign next_pv[3:1] = pv[3:1] & {3{~reset}}; |
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| 59 | assign next_pv[0] = pv[0] | reset; |
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| 60 | |
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| 61 | dff_s #4 park_reg(.din (next_pv), |
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| 62 | .clk (clk), |
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| 63 | .q (park_vec), |
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| 64 | .se (se), .si(), .so()); |
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| 65 | |
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| 66 | // if noone requests, don't advance, otherwise we'll go back to 0 |
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| 67 | // and will not be fair to other requestors |
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| 68 | assign gv[0] = park_vec[3] & req_vec[0] | |
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| 69 | park_vec[2] & ~req_vec[3] & req_vec[0] | |
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| 70 | park_vec[1] & ~req_vec[2] & ~req_vec[3] & req_vec[0] | |
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| 71 | ~req_vec[1] & ~req_vec[2] & ~req_vec[3]; |
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| 72 | |
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| 73 | assign gv[1] = park_vec[0] & req_vec[1] | |
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| 74 | park_vec[3] & ~req_vec[0] & req_vec[1] | |
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| 75 | park_vec[2] & ~req_vec[3] & ~req_vec[0] & req_vec[1] | |
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| 76 | req_vec[1] & ~req_vec[2] & ~req_vec[3] & ~req_vec[0]; |
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| 77 | |
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| 78 | assign gv[2] = park_vec[1] & req_vec[2] | |
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| 79 | park_vec[0] & ~req_vec[1] & req_vec[2] | |
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| 80 | park_vec[3] & ~req_vec[0] & ~req_vec[1] & req_vec[2] | |
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| 81 | req_vec[2] & ~req_vec[3] & ~req_vec[0] & ~req_vec[1]; |
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| 82 | |
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| 83 | assign gv[3] = park_vec[2] & req_vec[3] | |
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| 84 | park_vec[1] & ~req_vec[2] & req_vec[3] | |
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| 85 | park_vec[0] & ~req_vec[1] & ~req_vec[2] & req_vec[3] | |
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| 86 | req_vec[3] & ~req_vec[0] & ~req_vec[1] & ~req_vec[2]; |
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| 87 | |
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| 88 | assign grant_vec[0] = gv[0] | rst_tri_enable; |
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| 89 | assign grant_vec[3:1] = gv[3:1] & {3{~rst_tri_enable}}; |
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| 90 | |
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| 91 | |
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| 92 | endmodule // sparc_ifu_rndrob |
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| 93 | |
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| 94 | |
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| 95 | |
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