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robfinch |
`timescale 1ns / 1ps
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// ============================================================================
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// __
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// \\__/ o\ (C) 2016-2018 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_bitfield.v
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//
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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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//
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`ifndef BFSET
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`define BFSET 4'd0
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`define BFCLR 4'd1
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`define BFCHG 4'd2
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`define BFINS 4'd3
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`define BFINSI 4'd4
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`define BFEXT 4'd5
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`define BFEXTU 4'd6
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`endif
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module FT64_bitfield(inst, a, b, o, masko);
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parameter DWIDTH=64;
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input [31:0] inst;
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input [DWIDTH-1:0] a;
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input [DWIDTH-1:0] b;
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output [DWIDTH-1:0] o;
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reg [DWIDTH-1:0] o;
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output [DWIDTH-1:0] masko;
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reg [DWIDTH-1:0] o1;
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reg [DWIDTH-1:0] o2;
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// generate mask
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reg [DWIDTH-1:0] mask;
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assign masko = mask;
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wire [3:0] op = inst[31:28];
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wire [5:0] mb = inst[21:16];
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wire [5:0] me = inst[27:22];
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wire [5:0] ml = me-mb; // mask length-1
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wire [63:0] imm = {59'd0,inst[10:6]};
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integer nn,n;
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always @(mb or me or nn)
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for (nn = 0; nn < DWIDTH; nn = nn + 1)
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mask[nn] <= (nn >= mb) ^ (nn <= me) ^ (me >= mb);
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always @(op,mask,b,a,imm,mb,ml)
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case (op)
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`BFINS: begin
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o2 = a << mb;
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for (n = 0; n < DWIDTH; n = n + 1) o[n] = (mask[n] ? o2[n] : b[n]);
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end
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`BFINSI: begin
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o2 = imm << mb;
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for (n = 0; n < DWIDTH; n = n + 1) o[n] = (mask[n] ? o2[n] : b[n]);
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end
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`BFSET: begin for (n = 0; n < DWIDTH; n = n + 1) o[n] = mask[n] ? 1'b1 : a[n]; end
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//`BFCLR: begin for (n = 0; n < DWIDTH; n = n + 1) o[n] = mask[n] ? 1'b0 : a[n]; end
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`BFCHG: begin for (n = 0; n < DWIDTH; n = n + 1) o[n] = mask[n] ? ~a[n] : a[n]; end
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`BFEXTU: begin
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for (n = 0; n < DWIDTH; n = n + 1)
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o1[n] = mask[n] ? a[n] : 1'b0;
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o = o1 >> mb;
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end
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`BFEXT: begin
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for (n = 0; n < DWIDTH; n = n + 1)
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o1[n] = mask[n] ? a[n] : 1'b0;
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o2 = o1 >> mb;
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for (n = 0; n < DWIDTH; n = n + 1)
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o[n] = n > ml ? o2[ml] : o2[n];
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end
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`ifdef I_SEXT
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`SEXT: begin for (n = 0; n < DWIDTH; n = n + 1) o[n] = mask[n] ? a[mb] : a[n]; end
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`endif
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default: o = {DWIDTH{1'b0}};
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endcase
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endmodule
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