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// Filename: rxecrc.v
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// Filename: rxecrc.v
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//
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//
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// Project: OpenArty, an entirely open SoC based upon the Arty platform
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// Project: OpenArty, an entirely open SoC based upon the Arty platform
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//
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//
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// Purpose: To detect any CRC errors in the packet as received. The CRC
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// Purpose: To detect any CRC errors in the packet as received. The CRC
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// is not stripped as part of this process.
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// is not stripped as part of this process. However, any bytes
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// following the CRC, up to four, will be stripped from the output.
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//
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//
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// Creator: Dan Gisselquist, Ph.D.
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// Creator: Dan Gisselquist, Ph.D.
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// Gisselquist Technology, LLC
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// Gisselquist Technology, LLC
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//
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//
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////////////////////////////////////////////////////////////////////////////////
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////////////////////////////////////////////////////////////////////////////////
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wire [3:0] lownibble;
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wire [3:0] lownibble;
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assign lownibble = r_crc[3:0] ^ i_d;
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assign lownibble = r_crc[3:0] ^ i_d;
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wire [31:0] shifted_crc;
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wire [31:0] shifted_crc;
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assign shifted_crc = { 4'h0, r_crc[27:0] };
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assign shifted_crc = { 4'h0, r_crc[31:4] };
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always @(posedge i_clk)
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always @(posedge i_clk)
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if (i_ce)
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if (i_ce)
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begin
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begin
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r_crc_q0 <= r_crc[31:4];
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r_crc_q0 <= r_crc[31:4];
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Line 80... |
r_crc_q4 <= r_crc_q3[15:4];
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r_crc_q4 <= r_crc_q3[15:4];
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r_crc_q5 <= r_crc_q4[11:4];
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r_crc_q5 <= r_crc_q4[11:4];
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r_crc_q6 <= r_crc_q5[ 7:4];
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r_crc_q6 <= r_crc_q5[ 7:4];
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r_buf <= { r_buf[9:0], i_v, i_d };
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r_buf <= { r_buf[9:0], i_v, i_d };
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if (((!i_ce)&&(!o_v))||(i_cancel))
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if (((!i_v)&&(!o_v))||(i_cancel))
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begin
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begin
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r_crc <= 32'hffff_ffff;
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r_crc <= 32'hffff_ffff;
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r_err <= 1'b0;
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r_err <= 1'b0;
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r_mq[6:0] <= 7'h0;
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r_mq[6:0] <= 7'h0;
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4'hd: r_crc <= shifted_crc ^ `CRCBIT8 ^ `CRCBIT4 ^ `CRCBIT1;
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4'hd: r_crc <= shifted_crc ^ `CRCBIT8 ^ `CRCBIT4 ^ `CRCBIT1;
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4'he: r_crc <= shifted_crc ^ `CRCBIT8 ^ `CRCBIT4 ^ `CRCBIT2;
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4'he: r_crc <= shifted_crc ^ `CRCBIT8 ^ `CRCBIT4 ^ `CRCBIT2;
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4'hf: r_crc <= shifted_crc ^ `CRCBIT8 ^ `CRCBIT4 ^ `CRCBIT2 ^ `CRCBIT1;
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4'hf: r_crc <= shifted_crc ^ `CRCBIT8 ^ `CRCBIT4 ^ `CRCBIT2 ^ `CRCBIT1;
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endcase
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endcase
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r_mq[0] <= (i_v)&&(i_d == r_crc[3:0]);
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r_mq[0] <= (i_v)&&(i_d == (~r_crc[3:0]));
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r_mq[1] <= (r_mq[0])&&(i_v)&&(i_d == r_crc_q0[3:0]);
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r_mq[1] <= (r_mq[0])&&(i_v)&&(i_d == (~r_crc_q0[3:0]));
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r_mq[2] <= (r_mq[1])&&(i_v)&&(i_d == r_crc_q1[3:0]);
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r_mq[2] <= (r_mq[1])&&(i_v)&&(i_d == (~r_crc_q1[3:0]));
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r_mq[3] <= (r_mq[2])&&(i_v)&&(i_d == r_crc_q2[3:0]);
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r_mq[3] <= (r_mq[2])&&(i_v)&&(i_d == (~r_crc_q2[3:0]));
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r_mq[4] <= (r_mq[3])&&(i_v)&&(i_d == r_crc_q3[3:0]);
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r_mq[4] <= (r_mq[3])&&(i_v)&&(i_d == (~r_crc_q3[3:0]));
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r_mq[5] <= (r_mq[4])&&(i_v)&&(i_d == r_crc_q4[3:0]);
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r_mq[5] <= (r_mq[4])&&(i_v)&&(i_d == (~r_crc_q4[3:0]));
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r_mq[6] <= (r_mq[5])&&(i_v)&&(i_d == r_crc_q5[3:0]);
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r_mq[6] <= (r_mq[5])&&(i_v)&&(i_d == (~r_crc_q5[3:0]));
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//r_mq7<=(r_mq6)&&(i_v)&&(i_d == r_crc_q6[3:0]);
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//r_mq7<=(r_mq6)&&(i_v)&&(i_d == r_crc_q6[3:0]);
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r_mp <= { r_mp[2:0],
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r_mp <= { r_mp[2:0],
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(r_mq[6])&&(i_v)&&(i_d == r_crc_q6[3:0]) };
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(r_mq[6])&&(i_v)&&(i_d == (~r_crc_q6[3:0])) };
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// Now, we have an error if ...
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// Now, we have an error if ...
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// On the first empty, none of the prior N matches
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// On the first empty, none of the prior N matches
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// matched.
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// matched.
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r_err <= (r_err)||((i_en)&&(!i_v)&&(r_buf[4])&&(r_mp == 4'h0));
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r_err <= (r_err)||((i_en)&&(!i_v)&&(r_buf[4])&&(r_mp == 4'h0));
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