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/////////////////////////////////////////////////////////////////////////////

//
// 32 bit CRC of 31 data bits (forward - LSB first)
// polynomial : 00a00805 
//    x^23 + x^21 + x^11 + x^2 + x^0
//
//        CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD 
//        00000000001111111111222222222233 0000000000111111111122222222223 
//        01234567890123456789012345678901 0123456789012345678901234567890 
// C00  = .#........#.#......#..##....#.## ............................... 
// C01  = ..#........#.#......#..##....#.# ............................... 
// C02  = .#.#......#...#....#.#####..#..# ............................... 
// C03  = ..#.#......#...#....#.#####..#.. ............................... 
// C04  = ...#.#......#...#....#.#####..#. ............................... 
// C05  = ....#.#......#...#....#.#####..# ............................... 
// C06  = .....#.#......#...#....#.#####.. ............................... 
// C07  = ......#.#......#...#....#.#####. ............................... 
// C08  = .......#.#......#...#....#.##### ............................... 
// C09  = ........#.#......#...#....#.#### ............................... 
// C10  = .........#.#......#...#....#.### ............................... 
// C11  = .#....................#......... ............................... 
// C12  = ..#....................#........ ............................... 
// C13  = ...#....................#....... ............................... 
// C14  = ....#....................#...... ............................... 
// C15  = .....#....................#..... ............................... 
// C16  = ......#....................#.... ............................... 
// C17  = .......#....................#... ............................... 
// C18  = ........#....................#.. ............................... 
// C19  = .........#....................#. ............................... 
// C20  = ..........#....................# ............................... 
// C21  = .#........###......#..##....#.## ............................... 
// C22  = ..#........###......#..##....#.# ............................... 
// C23  = .#.#......#..##....#.#####..#..# ............................... 
// C24  = ..#.#......#..##....#.#####..#.. ............................... 
// C25  = ...#.#......#..##....#.#####..#. ............................... 
// C26  = ....#.#......#..##....#.#####..# ............................... 
// C27  = .....#.#......#..##....#.#####.. ............................... 
// C28  = ......#.#......#..##....#.#####. ............................... 
// C29  = .......#.#......#..##....#.##### ............................... 
// C30  = ........#.#......#..##....#.#### ............................... 
// C31  = #........#.#......#..##....#.### ............................... 
//
// Number of XORs used is 32
// Maximum XOR input count is 13
//   Best possible depth in 4 LUTs = 2
//   Best possible depth in 5 LUTs = 2
//   Best possible depth in 6 LUTs = 2
// Total XOR inputs 250
//

module fec_rot_31 (
    input [31:0] c,
    output [31:0] co
);

assign co[0] =
    c[1] ^ c[10] ^ c[12] ^ c[19] ^ c[22] ^ c[23] ^ 
    c[28] ^ c[30] ^ c[31];

assign co[1] =
    c[2] ^ c[11] ^ c[13] ^ c[20] ^ c[23] ^ c[24] ^ 
    c[29] ^ c[31];

assign co[2] =
    c[1] ^ c[3] ^ c[10] ^ c[14] ^ c[19] ^ c[21] ^ 
    c[22] ^ c[23] ^ c[24] ^ c[25] ^ c[28] ^ c[31];

assign co[3] =
    c[2] ^ c[4] ^ c[11] ^ c[15] ^ c[20] ^ c[22] ^ 
    c[23] ^ c[24] ^ c[25] ^ c[26] ^ c[29];

assign co[4] =
    c[3] ^ c[5] ^ c[12] ^ c[16] ^ c[21] ^ c[23] ^ 
    c[24] ^ c[25] ^ c[26] ^ c[27] ^ c[30];

assign co[5] =
    c[4] ^ c[6] ^ c[13] ^ c[17] ^ c[22] ^ c[24] ^ 
    c[25] ^ c[26] ^ c[27] ^ c[28] ^ c[31];

assign co[6] =
    c[5] ^ c[7] ^ c[14] ^ c[18] ^ c[23] ^ c[25] ^ 
    c[26] ^ c[27] ^ c[28] ^ c[29];

assign co[7] =
    c[6] ^ c[8] ^ c[15] ^ c[19] ^ c[24] ^ c[26] ^ 
    c[27] ^ c[28] ^ c[29] ^ c[30];

assign co[8] =
    c[7] ^ c[9] ^ c[16] ^ c[20] ^ c[25] ^ c[27] ^ 
    c[28] ^ c[29] ^ c[30] ^ c[31];

assign co[9] =
    c[8] ^ c[10] ^ c[17] ^ c[21] ^ c[26] ^ c[28] ^ 
    c[29] ^ c[30] ^ c[31];

assign co[10] =
    c[9] ^ c[11] ^ c[18] ^ c[22] ^ c[27] ^ c[29] ^ 
    c[30] ^ c[31];

assign co[11] =
    c[1] ^ c[22];

assign co[12] =
    c[2] ^ c[23];

assign co[13] =
    c[3] ^ c[24];

assign co[14] =
    c[4] ^ c[25];

assign co[15] =
    c[5] ^ c[26];

assign co[16] =
    c[6] ^ c[27];

assign co[17] =
    c[7] ^ c[28];

assign co[18] =
    c[8] ^ c[29];

assign co[19] =
    c[9] ^ c[30];

assign co[20] =
    c[10] ^ c[31];

assign co[21] =
    c[1] ^ c[10] ^ c[11] ^ c[12] ^ c[19] ^ c[22] ^ 
    c[23] ^ c[28] ^ c[30] ^ c[31];

assign co[22] =
    c[2] ^ c[11] ^ c[12] ^ c[13] ^ c[20] ^ c[23] ^ 
    c[24] ^ c[29] ^ c[31];

assign co[23] =
    c[1] ^ c[3] ^ c[10] ^ c[13] ^ c[14] ^ c[19] ^ 
    c[21] ^ c[22] ^ c[23] ^ c[24] ^ c[25] ^ c[28] ^ c[31];

assign co[24] =
    c[2] ^ c[4] ^ c[11] ^ c[14] ^ c[15] ^ c[20] ^ 
    c[22] ^ c[23] ^ c[24] ^ c[25] ^ c[26] ^ c[29];

assign co[25] =
    c[3] ^ c[5] ^ c[12] ^ c[15] ^ c[16] ^ c[21] ^ 
    c[23] ^ c[24] ^ c[25] ^ c[26] ^ c[27] ^ c[30];

assign co[26] =
    c[4] ^ c[6] ^ c[13] ^ c[16] ^ c[17] ^ c[22] ^ 
    c[24] ^ c[25] ^ c[26] ^ c[27] ^ c[28] ^ c[31];

assign co[27] =
    c[5] ^ c[7] ^ c[14] ^ c[17] ^ c[18] ^ c[23] ^ 
    c[25] ^ c[26] ^ c[27] ^ c[28] ^ c[29];

assign co[28] =
    c[6] ^ c[8] ^ c[15] ^ c[18] ^ c[19] ^ c[24] ^ 
    c[26] ^ c[27] ^ c[28] ^ c[29] ^ c[30];

assign co[29] =
    c[7] ^ c[9] ^ c[16] ^ c[19] ^ c[20] ^ c[25] ^ 
    c[27] ^ c[28] ^ c[29] ^ c[30] ^ c[31];

assign co[30] =
    c[8] ^ c[10] ^ c[17] ^ c[20] ^ c[21] ^ c[26] ^ 
    c[28] ^ c[29] ^ c[30] ^ c[31];

assign co[31] =
    c[0] ^ c[9] ^ c[11] ^ c[18] ^ c[21] ^ c[22] ^ 
    c[27] ^ c[29] ^ c[30] ^ c[31];

endmodule