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// -*- verilog -*-
//
// USRP - Universal Software Radio Peripheral
//
// Copyright (C) 2005,2006 Matt Ettus
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This 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 program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//
module shifter(input wire [33:0] in, output wire [15:0] out, input wire [7:0] shift);
// Wish we could do assign out = in[15+shift:shift];
reg [15:0] quotient, remainder;
wire [15:0] out_unclipped;
reg [18:0] msbs;
wire in_range;
always @*
case(shift)
0 : quotient = in[15:0];
1 : quotient = in[16:1];
2 : quotient = in[17:2];
3 : quotient = in[18:3];
4 : quotient = in[19:4];
5 : quotient = in[20:5];
6 : quotient = in[21:6];
7 : quotient = in[22:7];
8 : quotient = in[23:8];
9 : quotient = in[24:9];
10 : quotient = in[25:10];
11 : quotient = in[26:11];
12 : quotient = in[27:12];
13 : quotient = in[28:13];
14 : quotient = in[29:14];
15 : quotient = in[30:15];
16 : quotient = in[31:16];
17 : quotient = in[32:17];
18 : quotient = in[33:18];
default : quotient = in[15:0];
endcase // case(shift)
always @*
case(shift)
0 : remainder = 16'b0;
1 : remainder = {in[0],15'b0};
2 : remainder = {in[1:0],14'b0};
3 : remainder = {in[2:0],13'b0};
4 : remainder = {in[3:0],12'b0};
5 : remainder = {in[4:0],11'b0};
6 : remainder = {in[5:0],10'b0};
7 : remainder = {in[6:0],9'b0};
8 : remainder = {in[7:0],8'b0};
9 : remainder = {in[8:0],7'b0};
10 : remainder = {in[9:0],6'b0};
11 : remainder = {in[10:0],5'b0};
12 : remainder = {in[11:0],4'b0};
13 : remainder = {in[12:0],3'b0};
14 : remainder = {in[13:0],2'b0};
15 : remainder = {in[14:0],1'b0};
16 : remainder = in[15:0];
17 : remainder = in[16:1];
18 : remainder = in[17:2];
default : remainder = 16'b0;
endcase // case(shift)
always @*
case(shift)
0 : msbs = in[33:15];
1 : msbs = {in[33],in[33:16]};
2 : msbs = {{2{in[33]}},in[33:17]};
3 : msbs = {{3{in[33]}},in[33:18]};
4 : msbs = {{4{in[33]}},in[33:19]};
5 : msbs = {{5{in[33]}},in[33:20]};
6 : msbs = {{6{in[33]}},in[33:21]};
7 : msbs = {{7{in[33]}},in[33:22]};
8 : msbs = {{8{in[33]}},in[33:23]};
9 : msbs = {{9{in[33]}},in[33:24]};
10 : msbs = {{10{in[33]}},in[33:25]};
11 : msbs = {{11{in[33]}},in[33:26]};
12 : msbs = {{12{in[33]}},in[33:27]};
13 : msbs = {{13{in[33]}},in[33:28]};
14 : msbs = {{14{in[33]}},in[33:29]};
15 : msbs = {{15{in[33]}},in[33:30]};
16 : msbs = {{16{in[33]}},in[33:31]};
17 : msbs = {{17{in[33]}},in[33:32]};
18 : msbs = {{18{in[33]}},in[33]};
default : msbs = in[33:15];
endcase // case(shift)
assign in_range = &msbs | ~(|msbs);
assign out_unclipped = quotient + (in[33] & |remainder);
assign out = in_range ? out_unclipped : {in[33],{15{~in[33]}}};
endmodule // shifter
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