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244 lines
11 KiB
Verilog
244 lines
11 KiB
Verilog
`timescale 1ns / 1ps
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/* memc_translator.v
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Copyright (c) 2012-2014, Stephen J. Leary
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the <organization> nor the
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* names of its contributors may be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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module memc_translator
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(
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input clkcpu,
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input wr, // write to the page table
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input [1:0] page_size,
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input spvmd,
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input osmd,
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input mem_write,
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input [25:0] addr_i,
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output [25:0] addr_o,
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output valid
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);
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localparam PAGE_TABLE_SIZE = 128;
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// Memory protection truth table.
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// | 00 | 01 | 10 | 11 |
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// -----|------|------|------|------|
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// SPVMD| R/W | R/W | R/W | R/W |
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// OSMD| R/W | R/W | R | R |
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// USRMD| R/W | R | - | - |
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// |------|------|------|------|
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// address translation table.
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// TODO: other memory sizes?
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// if the OS uses different memory sizes at startup i'll implement it
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// otherwise i'll make it fixed at synth time.
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// ppn swizzle for 32K page size.
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// could potentially get 16Mb here by making 512 pages.
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wire [6:0] ppn = page_size == 2'b00 ? {addr_i[6:0]} :
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page_size == 2'b01 ? {addr_i[0], addr_i[6:1]} :
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page_size == 2'b10 ? {addr_i[1:0], addr_i[6:2]} :
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{addr_i[1], addr_i[2], addr_i[0], addr_i[6:3]};
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genvar c;
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generate
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for (c = 0; c < PAGE_TABLE_SIZE; c = c + 1) begin: pgentry
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reg[14:0] r = 0; // register for this table entry.
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wire prot = spvmd | (osmd & ~mem_write) | (osmd & mem_write & r[14]) | ~r[14] & r[13] & ~mem_write | ~r[14] & ~r[13];
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wire en = r[12:3] == addr_i[24:15] & prot; // lookup logic when this table is active.
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wire sel = ppn[6:0] == c[6:0]; // select logic for this page table (for writing table)
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wire [25:0] addr = {4'b0000, c[6:0], addr_i[14:0]};
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always @(posedge clkcpu) begin
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if (wr & sel) begin
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// code to program the table
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r <= {addr_i[9:8], addr_i[11:10], addr_i[22:12]};
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$display("writing to table entry %d := %x (%x)", c, {addr_i[9:8], addr_i[11:10], addr_i[22:12]}, addr_i);
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end
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end
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end
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endgenerate
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// 128 to 1 decode.
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assign addr_o = pgentry[0].en ? pgentry[0].addr :
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pgentry[1].en ? pgentry[1].addr :
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pgentry[2].en ? pgentry[2].addr :
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pgentry[3].en ? pgentry[3].addr :
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pgentry[4].en ? pgentry[4].addr :
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pgentry[5].en ? pgentry[5].addr :
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pgentry[6].en ? pgentry[6].addr :
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pgentry[7].en ? pgentry[7].addr :
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pgentry[8].en ? pgentry[8].addr :
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pgentry[9].en ? pgentry[9].addr :
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pgentry[10].en ? pgentry[10].addr :
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pgentry[11].en ? pgentry[11].addr :
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pgentry[12].en ? pgentry[12].addr :
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pgentry[13].en ? pgentry[13].addr :
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pgentry[14].en ? pgentry[14].addr :
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pgentry[15].en ? pgentry[15].addr :
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pgentry[16].en ? pgentry[16].addr :
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pgentry[17].en ? pgentry[17].addr :
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pgentry[18].en ? pgentry[18].addr :
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pgentry[19].en ? pgentry[19].addr :
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pgentry[20].en ? pgentry[20].addr :
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pgentry[21].en ? pgentry[21].addr :
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pgentry[22].en ? pgentry[22].addr :
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pgentry[23].en ? pgentry[23].addr :
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pgentry[24].en ? pgentry[24].addr :
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pgentry[25].en ? pgentry[25].addr :
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pgentry[26].en ? pgentry[26].addr :
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pgentry[27].en ? pgentry[27].addr :
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pgentry[28].en ? pgentry[28].addr :
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pgentry[29].en ? pgentry[29].addr :
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pgentry[30].en ? pgentry[30].addr :
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pgentry[31].en ? pgentry[31].addr :
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pgentry[32].en ? pgentry[32].addr :
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pgentry[33].en ? pgentry[33].addr :
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pgentry[34].en ? pgentry[34].addr :
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pgentry[35].en ? pgentry[35].addr :
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pgentry[36].en ? pgentry[36].addr :
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pgentry[37].en ? pgentry[37].addr :
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pgentry[38].en ? pgentry[38].addr :
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pgentry[39].en ? pgentry[39].addr :
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pgentry[40].en ? pgentry[40].addr :
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pgentry[41].en ? pgentry[41].addr :
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pgentry[42].en ? pgentry[42].addr :
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pgentry[43].en ? pgentry[43].addr :
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pgentry[44].en ? pgentry[44].addr :
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pgentry[45].en ? pgentry[45].addr :
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pgentry[46].en ? pgentry[46].addr :
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pgentry[47].en ? pgentry[47].addr :
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pgentry[48].en ? pgentry[48].addr :
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pgentry[49].en ? pgentry[49].addr :
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pgentry[50].en ? pgentry[50].addr :
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pgentry[51].en ? pgentry[51].addr :
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pgentry[52].en ? pgentry[52].addr :
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pgentry[53].en ? pgentry[53].addr :
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pgentry[54].en ? pgentry[54].addr :
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pgentry[55].en ? pgentry[55].addr :
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pgentry[56].en ? pgentry[56].addr :
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pgentry[57].en ? pgentry[57].addr :
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pgentry[58].en ? pgentry[58].addr :
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pgentry[59].en ? pgentry[59].addr :
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pgentry[60].en ? pgentry[60].addr :
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pgentry[61].en ? pgentry[61].addr :
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pgentry[62].en ? pgentry[62].addr :
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pgentry[63].en ? pgentry[63].addr :
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pgentry[64].en ? pgentry[64].addr :
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pgentry[65].en ? pgentry[65].addr :
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pgentry[66].en ? pgentry[66].addr :
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pgentry[67].en ? pgentry[67].addr :
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pgentry[68].en ? pgentry[68].addr :
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pgentry[69].en ? pgentry[69].addr :
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pgentry[70].en ? pgentry[70].addr :
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pgentry[71].en ? pgentry[71].addr :
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pgentry[72].en ? pgentry[72].addr :
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pgentry[73].en ? pgentry[73].addr :
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pgentry[74].en ? pgentry[74].addr :
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pgentry[75].en ? pgentry[75].addr :
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pgentry[76].en ? pgentry[76].addr :
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pgentry[77].en ? pgentry[77].addr :
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pgentry[78].en ? pgentry[78].addr :
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pgentry[79].en ? pgentry[79].addr :
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pgentry[80].en ? pgentry[80].addr :
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pgentry[81].en ? pgentry[81].addr :
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pgentry[82].en ? pgentry[82].addr :
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pgentry[83].en ? pgentry[83].addr :
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pgentry[84].en ? pgentry[84].addr :
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pgentry[85].en ? pgentry[85].addr :
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pgentry[86].en ? pgentry[86].addr :
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pgentry[87].en ? pgentry[87].addr :
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pgentry[88].en ? pgentry[88].addr :
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pgentry[89].en ? pgentry[89].addr :
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pgentry[90].en ? pgentry[90].addr :
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pgentry[91].en ? pgentry[91].addr :
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pgentry[92].en ? pgentry[92].addr :
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pgentry[93].en ? pgentry[93].addr :
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pgentry[94].en ? pgentry[94].addr :
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pgentry[95].en ? pgentry[95].addr :
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pgentry[96].en ? pgentry[96].addr :
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pgentry[97].en ? pgentry[97].addr :
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pgentry[98].en ? pgentry[98].addr :
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pgentry[99].en ? pgentry[99].addr :
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pgentry[100].en ? pgentry[100].addr :
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pgentry[101].en ? pgentry[101].addr :
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pgentry[102].en ? pgentry[102].addr :
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pgentry[103].en ? pgentry[103].addr :
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pgentry[104].en ? pgentry[104].addr :
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pgentry[105].en ? pgentry[105].addr :
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pgentry[106].en ? pgentry[106].addr :
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pgentry[107].en ? pgentry[107].addr :
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pgentry[108].en ? pgentry[108].addr :
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pgentry[109].en ? pgentry[109].addr :
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pgentry[110].en ? pgentry[110].addr :
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pgentry[111].en ? pgentry[111].addr :
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pgentry[112].en ? pgentry[112].addr :
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pgentry[113].en ? pgentry[113].addr :
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pgentry[114].en ? pgentry[114].addr :
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pgentry[115].en ? pgentry[115].addr :
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pgentry[116].en ? pgentry[116].addr :
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pgentry[117].en ? pgentry[117].addr :
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pgentry[118].en ? pgentry[118].addr :
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pgentry[119].en ? pgentry[119].addr :
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pgentry[120].en ? pgentry[120].addr :
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pgentry[121].en ? pgentry[121].addr :
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pgentry[122].en ? pgentry[122].addr :
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pgentry[123].en ? pgentry[123].addr :
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pgentry[124].en ? pgentry[124].addr :
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pgentry[125].en ? pgentry[125].addr :
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pgentry[126].en ? pgentry[126].addr :
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pgentry[127].en ? pgentry[127].addr : 26'd0;
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assign valid = pgentry[0].en | pgentry[1].en | pgentry[2].en | pgentry[3].en | pgentry[4].en | pgentry[5].en | pgentry[6].en | pgentry[7].en |
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pgentry[8].en | pgentry[9].en | pgentry[10].en | pgentry[11].en | pgentry[12].en | pgentry[13].en | pgentry[14].en | pgentry[15].en |
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pgentry[16].en | pgentry[17].en | pgentry[18].en | pgentry[19].en | pgentry[20].en | pgentry[21].en | pgentry[22].en | pgentry[23].en |
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pgentry[24].en | pgentry[25].en | pgentry[26].en | pgentry[27].en | pgentry[28].en | pgentry[29].en | pgentry[30].en | pgentry[31].en |
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pgentry[32].en | pgentry[33].en | pgentry[34].en | pgentry[35].en | pgentry[36].en | pgentry[37].en | pgentry[38].en | pgentry[39].en |
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pgentry[40].en | pgentry[41].en | pgentry[42].en | pgentry[43].en | pgentry[44].en | pgentry[45].en | pgentry[46].en | pgentry[47].en |
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pgentry[48].en | pgentry[49].en | pgentry[50].en | pgentry[51].en | pgentry[52].en | pgentry[53].en | pgentry[54].en | pgentry[55].en |
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pgentry[56].en | pgentry[57].en | pgentry[58].en | pgentry[59].en | pgentry[60].en | pgentry[61].en | pgentry[62].en | pgentry[63].en |
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pgentry[64].en | pgentry[65].en | pgentry[66].en | pgentry[67].en | pgentry[68].en | pgentry[69].en | pgentry[70].en | pgentry[71].en |
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pgentry[72].en | pgentry[73].en | pgentry[74].en | pgentry[75].en | pgentry[76].en | pgentry[77].en | pgentry[78].en | pgentry[79].en |
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pgentry[80].en | pgentry[81].en | pgentry[82].en | pgentry[83].en | pgentry[84].en | pgentry[85].en | pgentry[86].en | pgentry[87].en |
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pgentry[88].en | pgentry[89].en | pgentry[90].en | pgentry[91].en | pgentry[92].en | pgentry[93].en | pgentry[94].en | pgentry[95].en |
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pgentry[96].en | pgentry[97].en | pgentry[98].en | pgentry[99].en | pgentry[100].en | pgentry[101].en | pgentry[102].en | pgentry[103].en |
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pgentry[104].en | pgentry[105].en | pgentry[106].en | pgentry[107].en | pgentry[108].en | pgentry[109].en | pgentry[110].en | pgentry[111].en |
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pgentry[112].en | pgentry[113].en | pgentry[114].en | pgentry[115].en | pgentry[116].en | pgentry[117].en | pgentry[118].en | pgentry[119].en |
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pgentry[120].en | pgentry[121].en | pgentry[122].en | pgentry[123].en | pgentry[124].en | pgentry[125].en | pgentry[126].en | pgentry[127].en;
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endmodule
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