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Diffstat (limited to 'source/fcs.v')
| -rw-r--r-- | source/fcs.v | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/source/fcs.v b/source/fcs.v new file mode 100644 index 0000000..6abf536 --- /dev/null +++ b/source/fcs.v @@ -0,0 +1,142 @@ +/* + * fcs.v + * + * Copyright (C) 2018, 2019 Mind Chasers Inc. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + * + * function: FCS checksum + * + * + */ +`timescale 1ns /10ps + +//////////////////////////////////////////////////////////////////////////////// +// Copyright (C) 1999-2008 Easics NV. +// This source file may be used and distributed without restriction +// provided that this copyright statement is not removed from the file +// and that any derivative work contains the original copyright notice +// and the associated disclaimer. +// +// THIS SOURCE FILE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS +// OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED +// WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. +// +// Purpose : synthesizable CRC function +// * polynomial: x^32 + x^26 + x^23 + x^22 + x^16 + x^12 + x^11 + x^10 + x^8 + x^7 + x^5 + x^4 + x^2 + x^1 + 1 +// * data width: 8 +// +// Info : tools@easics.be +// http://www.easics.com +//////////////////////////////////////////////////////////////////////////////// + +/* +* a) The first 32 bits of the frame are complemented. +* b) The n bits of the MAC frame considered to be the coefficients of a polynomial M(x) of degree n � 1. +* The first bit of the Destination Address field corresponds to the x(n�1) term +* and the last bit of the MAC Client Data field (or Pad field if present) corresponds to the x0 term. +* c) M(x) is multiplied by x**32 and divided by G(x), producing a remainder R(x) of degree = 31. +* d) The coefficients of R(x) are considered to be a 32-bit sequence. +* e) The bit sequence is complemented and the result is the CRC. +* f) FCS should be trnansmitted msbit first ( opposite of the rest of MAC frame ) +*/ +module fcs( + input rstn, + input clk, + + // control interface + input init, + input enable, + + // addr & data + input [1:0] addr, + input [0:7] din, + output [7:0] dout +); + + +reg [31:0] crc; +reg [7:0] d; + +assign dout = ~{ d[0],d[1],d[2],d[3],d[4],d[5],d[6],d[7] }; + +always @(*) + begin + case(addr) + 2'b00: d <= crc[31:24]; + 2'b01: d <= crc[23:16]; + 2'b10: d <= crc[15:8]; + 2'b11: d <= crc[7:0]; + endcase + end + +always @(posedge clk or negedge rstn) + if(!rstn) + crc <= 32'hffffffff; + else if (init) + crc <= 32'hffffffff; + else if (enable) + crc <= nextCRC32_D8(din,crc); + +// {d[0],d[1],d[2],d[3],d[4],d[5],d[6],d[7]} + + // polynomial: x^32 + x^26 + x^23 + x^22 + x^16 + x^12 + x^11 + x^10 + x^8 + x^7 + x^5 + x^4 + x^2 + x^1 + 1 + // data width: 8 + // convention: the first serial bit is D[7] + function [31:0] nextCRC32_D8; + + input [0:7] Data; + input [31:0] crc; + reg [0:7] d; + reg [31:0] c; + reg [31:0] newcrc; + begin + d = Data; + c = crc; + + newcrc[0] = d[6] ^ d[0] ^ c[24] ^ c[30]; + newcrc[1] = d[7] ^ d[6] ^ d[1] ^ d[0] ^ c[24] ^ c[25] ^ c[30] ^ c[31]; + newcrc[2] = d[7] ^ d[6] ^ d[2] ^ d[1] ^ d[0] ^ c[24] ^ c[25] ^ c[26] ^ c[30] ^ c[31]; + newcrc[3] = d[7] ^ d[3] ^ d[2] ^ d[1] ^ c[25] ^ c[26] ^ c[27] ^ c[31]; + newcrc[4] = d[6] ^ d[4] ^ d[3] ^ d[2] ^ d[0] ^ c[24] ^ c[26] ^ c[27] ^ c[28] ^ c[30]; + newcrc[5] = d[7] ^ d[6] ^ d[5] ^ d[4] ^ d[3] ^ d[1] ^ d[0] ^ c[24] ^ c[25] ^ c[27] ^ c[28] ^ c[29] ^ c[30] ^ c[31]; + newcrc[6] = d[7] ^ d[6] ^ d[5] ^ d[4] ^ d[2] ^ d[1] ^ c[25] ^ c[26] ^ c[28] ^ c[29] ^ c[30] ^ c[31]; + newcrc[7] = d[7] ^ d[5] ^ d[3] ^ d[2] ^ d[0] ^ c[24] ^ c[26] ^ c[27] ^ c[29] ^ c[31]; + newcrc[8] = d[4] ^ d[3] ^ d[1] ^ d[0] ^ c[0] ^ c[24] ^ c[25] ^ c[27] ^ c[28]; + newcrc[9] = d[5] ^ d[4] ^ d[2] ^ d[1] ^ c[1] ^ c[25] ^ c[26] ^ c[28] ^ c[29]; + newcrc[10] = d[5] ^ d[3] ^ d[2] ^ d[0] ^ c[2] ^ c[24] ^ c[26] ^ c[27] ^ c[29]; + newcrc[11] = d[4] ^ d[3] ^ d[1] ^ d[0] ^ c[3] ^ c[24] ^ c[25] ^ c[27] ^ c[28]; + newcrc[12] = d[6] ^ d[5] ^ d[4] ^ d[2] ^ d[1] ^ d[0] ^ c[4] ^ c[24] ^ c[25] ^ c[26] ^ c[28] ^ c[29] ^ c[30]; + newcrc[13] = d[7] ^ d[6] ^ d[5] ^ d[3] ^ d[2] ^ d[1] ^ c[5] ^ c[25] ^ c[26] ^ c[27] ^ c[29] ^ c[30] ^ c[31]; + newcrc[14] = d[7] ^ d[6] ^ d[4] ^ d[3] ^ d[2] ^ c[6] ^ c[26] ^ c[27] ^ c[28] ^ c[30] ^ c[31]; + newcrc[15] = d[7] ^ d[5] ^ d[4] ^ d[3] ^ c[7] ^ c[27] ^ c[28] ^ c[29] ^ c[31]; + newcrc[16] = d[5] ^ d[4] ^ d[0] ^ c[8] ^ c[24] ^ c[28] ^ c[29]; + newcrc[17] = d[6] ^ d[5] ^ d[1] ^ c[9] ^ c[25] ^ c[29] ^ c[30]; + newcrc[18] = d[7] ^ d[6] ^ d[2] ^ c[10] ^ c[26] ^ c[30] ^ c[31]; + newcrc[19] = d[7] ^ d[3] ^ c[11] ^ c[27] ^ c[31]; + newcrc[20] = d[4] ^ c[12] ^ c[28]; + newcrc[21] = d[5] ^ c[13] ^ c[29]; + newcrc[22] = d[0] ^ c[14] ^ c[24]; + newcrc[23] = d[6] ^ d[1] ^ d[0] ^ c[15] ^ c[24] ^ c[25] ^ c[30]; + newcrc[24] = d[7] ^ d[2] ^ d[1] ^ c[16] ^ c[25] ^ c[26] ^ c[31]; + newcrc[25] = d[3] ^ d[2] ^ c[17] ^ c[26] ^ c[27]; + newcrc[26] = d[6] ^ d[4] ^ d[3] ^ d[0] ^ c[18] ^ c[24] ^ c[27] ^ c[28] ^ c[30]; + newcrc[27] = d[7] ^ d[5] ^ d[4] ^ d[1] ^ c[19] ^ c[25] ^ c[28] ^ c[29] ^ c[31]; + newcrc[28] = d[6] ^ d[5] ^ d[2] ^ c[20] ^ c[26] ^ c[29] ^ c[30]; + newcrc[29] = d[7] ^ d[6] ^ d[3] ^ c[21] ^ c[27] ^ c[30] ^ c[31]; + newcrc[30] = d[7] ^ d[4] ^ c[22] ^ c[28] ^ c[31]; + newcrc[31] = d[5] ^ c[23] ^ c[29]; + nextCRC32_D8 = newcrc; + end + endfunction +endmodule |