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robfinch |
// ============================================================================
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// __
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// \\__/ o\ (C) 2017-2018 Robert Finch, Waterloo
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// \ __ / All rights reserved.
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// \/_// robfinch<remove>@finitron.ca
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// ||
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//
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// FT64_EvalBranch.v
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// - FT64 branch evaluation
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//
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// This source file is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published
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// by the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This source file is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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//
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// ============================================================================
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//
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`define BccR 6'h03
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`define BBc0 6'h26
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`define BBc1 6'h27
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`define Bcc0 6'h30
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`define Bcc1 6'h31
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`define BEQ0 6'h32
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`define BEQ1 6'h33
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`define CHK 6'h34
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`define BEQ 4'h0
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`define BNE 4'h1
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`define BLT 4'h2
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`define BGE 4'h3
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`define BLTU 4'h4
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`define BGEU 4'h5
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`define FBEQ 4'h8
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`define FBNE 4'h9
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`define FBLT 4'hA
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`define FBGE 4'hB
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`define FBUN 4'hC
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`define DBNZ 3'd7
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module FT64_EvalBranch(instr, a, b, c, takb);
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parameter WID=64;
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input [31:0] instr;
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input [WID-1:0] a;
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input [WID-1:0] b;
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input [WID-1:0] c;
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output reg takb;
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wire [5:0] opcode = instr[5:0];
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wire [4:0] fcmpo;
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wire fnanx;
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fp_cmp_unit #(WID) ufcmp1 (a, b, fcmpo, fnanx);
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//Evaluate branch condition
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always @*
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case(opcode)
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`BccR:
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case(instr[24:21])
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`BEQ: takb <= a==b;
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`BNE: takb <= a!=b;
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`BLT: takb <= $signed(a) < $signed(b);
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`BGE: takb <= $signed(a) >= $signed(b);
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`BLTU: takb <= a < b;
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`BGEU: takb <= a >= b;
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`FBEQ: takb <= fcmpo[0];
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`FBNE: takb <= ~fcmpo[0];
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`FBLT: takb <= fcmpo[1];
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`FBGE: takb <= ~fcmpo[2];
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`FBUN: takb <= fcmpo[4];
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default: takb <= `TRUE;
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endcase
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`Bcc0,`Bcc1:
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case(instr[19:16])
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`BEQ: takb <= a==b;
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`BNE: takb <= a!=b;
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`BLT: takb <= $signed(a) < $signed(b);
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`BGE: takb <= $signed(a) >= $signed(b);
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`BLTU: takb <= a < b;
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`BGEU: takb <= a >= b;
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`FBEQ: takb <= fcmpo[0];
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`FBNE: takb <= ~fcmpo[0];
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`FBLT: takb <= fcmpo[1];
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`FBGE: takb <= ~fcmpo[2];
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`FBUN: takb <= fcmpo[4];
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default: takb <= `TRUE;
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endcase
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`BEQ0,`BEQ1: takb <= a=={{55{instr[19]}},instr[19:11]};
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`BBc0,`BBc1:
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case(instr[19:17])
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3'd0: takb <= a[instr[16:11]]; // BBS
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3'd1: takb <= ~a[instr[16:11]]; // BBC
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`DBNZ: takb <= a=={58'h0,instr[16:11]};
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default: takb <= `TRUE;
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endcase
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`CHK: takb <= a >= b && a < c;
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default: takb <= `TRUE;
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endcase
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endmodule
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