///// testbench_dedsec.v `include "clock.v" module top; integer x,y; reg [127:0] data; reg [25:0] dedsec; reg pass; c1 clock(sysclk); always begin @(posedge sysclk); // for (x=0;x // begin @(posedge sysclk); data = 128'heeeeffffffffffffffffffffffffffff; dedsec = dedsec_bits(data); pass_dedsec(data,dedsec,pass); dedsec = dedsec >> 1; $display("data=%h dedsec=%h pass=%h",data,dedsec,pass); @(posedge sysclk); data = 128'h11101110111000000000000000000000; dedsec = dedsec_bits(data); pass_dedsec(data,dedsec,pass); dedsec = dedsec >> 1; $display("data=%h dedsec=%h pass=%h",data,dedsec,pass); @(posedge sysclk); data = 128'h11101110111011101110111011100000; dedsec = dedsec_bits(data); pass_dedsec(data,dedsec,pass); dedsec = dedsec >> 1; $display("data=%h dedsec=%h pass=%h",data,dedsec,pass); @(posedge sysclk); data = 128'h00001110111011101110111011101110; dedsec = dedsec_bits(data); pass_dedsec(data,dedsec,pass); dedsec = dedsec >> 1; $display("data=%h dedsec=%h pass=%h",data,dedsec,pass); @(posedge sysclk); data = 128'h11101110111000000000000000000000; dedsec = dedsec_bits(data); dedsec[21] = 1'b0; dedsec[8] = 1'b0; $display("dedsec_pass test #1"); $display("data before : %h",data); pass_dedsec(data,dedsec,pass); $display("data after : %h, pass: %h", data,pass); @(posedge sysclk); data = 128'h11101110111000000000000000000000; dedsec = dedsec_bits(data); dedsec[8] = ~dedsec[8]; dedsec[7] = ~dedsec[7]; dedsec[6] = ~dedsec[6]; $display("dedsec_pass test #2"); $display("data before : %h",data); pass_dedsec(data,dedsec,pass); $display("data after : %h, pass: %h", data,pass); @(posedge sysclk); data = 128'h11101110111000000000000000000000; dedsec = dedsec_bits(data); dedsec[21] = 1'b0; dedsec[20] = ~dedsec[20]; dedsec[7] = 1'b0; $display("dedsec_pass test #3"); $display("data before : %h",data); pass_dedsec(data,dedsec,pass); $display("data after : %h, pass: %h", data,pass); @(posedge sysclk); data = 128'h11101110111000000000000000000000; dedsec = dedsec_bits(data); dedsec[21] = 1'b0; dedsec[7] = 1'b0; dedsec[0] = ~dedsec[0]; $display("dedsec_pass test #4"); $display("data before : %h",data); pass_dedsec(data,dedsec,pass); $display("data after : %h, pass: %h", data,pass); @(posedge sysclk); data = 128'h11101110111000000000000000000000; dedsec = dedsec_bits(data); dedsec[0] = ~dedsec[0]; $display("dedsec_pass test #5"); $display("data before : %h",data); pass_dedsec(data,dedsec,pass); $display("data after : %h, pass: %h", data,pass); @(posedge sysclk); data = 128'h11101110111000000000000000000000; dedsec = dedsec_bits(data); dedsec[21] = ~dedsec[21]; dedsec[0] = ~dedsec[0]; $display("dedsec_pass test #6"); $display("data before : %h",data); pass_dedsec(data,dedsec,pass); $display("data after : %h, pass: %h", data,pass); @(posedge sysclk); data = 128'h11101110111000000000000000000000; dedsec = dedsec_bits(data); dedsec[8] = ~dedsec[21]; dedsec[0] = ~dedsec[0]; $display("dedsec_pass test #7"); $display("data before : %h",data); pass_dedsec(data,dedsec,pass); $display("data after : %h, pass: %h", data,pass); // end $stop; $finish; end function [24:0] dedsec_bits; input [127:0] data; integer i,j; begin // Horizontal decsec bits // Calculate the horizontal dedsec bits on the bottom. // The code, rather silly, calculate the dedsec bits of the column of data one by one. dedsec_bits[24] = data[127]^data[111]^data[95]^data[79]^data[63]^data[47]^data[31]^data[15]; dedsec_bits[23] = data[126]^data[110]^data[94]^data[78]^data[62]^data[46]^data[30]^data[14]; dedsec_bits[22] = data[125]^data[109]^data[93]^data[77]^data[61]^data[45]^data[29]^data[13]; dedsec_bits[21] = data[124]^data[108]^data[92]^data[76]^data[60]^data[44]^data[28]^data[12]; dedsec_bits[20] = data[123]^data[107]^data[91]^data[75]^data[59]^data[43]^data[27]^data[11]; dedsec_bits[19] = data[122]^data[106]^data[90]^data[74]^data[58]^data[42]^data[26]^data[10]; dedsec_bits[18] = data[121]^data[105]^data[89]^data[73]^data[57]^data[41]^data[25]^data[ 9]; dedsec_bits[17] = data[120]^data[104]^data[88]^data[72]^data[56]^data[40]^data[24]^data[ 8]; dedsec_bits[16] = data[119]^data[103]^data[87]^data[71]^data[55]^data[39]^data[23]^data[ 7]; dedsec_bits[15] = data[118]^data[102]^data[86]^data[70]^data[54]^data[38]^data[22]^data[ 6]; dedsec_bits[14] = data[117]^data[101]^data[85]^data[69]^data[53]^data[37]^data[21]^data[ 5]; dedsec_bits[13] = data[116]^data[100]^data[84]^data[68]^data[52]^data[36]^data[20]^data[ 4]; dedsec_bits[12] = data[115]^data[ 99]^data[83]^data[67]^data[51]^data[35]^data[19]^data[ 3]; dedsec_bits[11] = data[114]^data[ 98]^data[82]^data[66]^data[50]^data[34]^data[18]^data[ 2]; dedsec_bits[10] = data[113]^data[ 97]^data[81]^data[65]^data[49]^data[33]^data[17]^data[ 1]; dedsec_bits[ 9] = data[112]^data[ 96]^data[80]^data[64]^data[48]^data[32]^data[16]^data[ 0]; // Vertical dedsec bits // Calculate the vertical dedsec bits on the right side. // The following eight line of code initialize the dedsec_bits, xoring the first two // data bits together. dedsec_bits[8]=data[127]^data[126]; dedsec_bits[7]=data[111]^data[110]; dedsec_bits[6]=data[95]^data[94]; dedsec_bits[5]=data[79]^data[78]; dedsec_bits[4]=data[63]^data[62]; dedsec_bits[3]=data[47]^data[46]; dedsec_bits[2]=data[31]^data[30]; dedsec_bits[1]=data[15]^data[14]; // The following double for-loop xor the rest of the data bits. for ( i=8 ; i>=1; i=i-1 ) begin for ( j=(i*16)-3; j>=((i-1)*16); j=j-1) begin dedsec_bits[i] = dedsec_bits[i] ^ data[j]; end end // Calculate the combined dedsec bit // As with the previous calculations, firstly xor the first two bits // together, then xor the rest of the bits in the for loop dedsec_bits[0]=dedsec_bits[1]^dedsec_bits[2]; for ( i=3 ; i begin dedsec_bits[0] = dedsec_bits[0] ^ dedsec_bits[i]; end // for ( i=3 ; i end endfunction // dedsec_bits // Returns whether the given data passes the DEDSEC test task pass_dedsec; inout [127:0] data; inout [24:0] dedsec; output pass_dedsec; reg [127:0] data; reg [24:0] dedsec; reg [24:0] old_dedsec; reg [24:0] new_dedsec; reg pass_dedsec; integer i, no_of_error, error_location1, error_location2, temp, l; begin no_of_error = 0; old_dedsec = dedsec; new_dedsec = dedsec_bits(data); // Calculate the number of error, as well as notice the location // of the errors for ( i = 24 ; i >= 0 ; i = i - 1 ) begin if ( old_dedsec[i] != new_dedsec[i] ) begin no_of_error = no_of_error + 1; if ( no_of_error == 1 ) begin error_location1 = i; end else if ( no_of_error == 2 ) begin error_location2 = i; end end end pass_dedsec = 1'b1; if ( no_of_error == 0 ) begin pass_dedsec = 1'b1; end else if ( error_location1 && error_location1 >= 9 && error_location2 >= 9 ) // Same row of bits contains error bits, can't recover begin pass_dedsec = 1'b0; end else if ( error_location1 && error_location1 >= 1 && error_location2 >= 1 ) // Same column of bits contains error bits, can't recover begin pass_dedsec = 1'b0; end else if ( no_of_error >= 3 ) // too many errors, can't recover begin pass_dedsec = 1'b0; end else if ( error_location1 == 0 && no_of_error == 1 ) begin // Just for the zeroth dedsec bit is in error. // Error correctable, just modify the corner bit of DEDSEC. // Recalculate the combined dedsec bit. dedsec[0]=dedsec[1]^dedsec[2]; for ( i=3 ; i begin dedsec[0] = dedsec[0] ^ dedsec[i]; end end else if ( error_location1 == 0 || error_location2 == 0) // One error bit in the 0th dedsec bit another in row/column. begin // Make error_location2 contains the nonzero location, to // unify the correcting process if ( error_location2 == 0) begin error_location2 = error_location1; error_location1 = 0; end // If the error location is the horizontal dedsec row, // then the dedsec bit is in error, recalculate that bit if ( error_location2 = 9 ) begin dedsec[error_location2] = data[error_location2] ^ data[error_location2+16]; for (i = 2; i begin dedsec[error_location2] = dedsec[error_location2] ^ data[error_location2 + 16 * i]; end end // If the error location is the vertical dedsec column // then the dedsec bit is in error, recalculate that bit if ( error_location2 = 1 ) begin dedsec[error_location2] = data[(error_location2-1)*16] ^ data[(error_location2-1)*16+1]; for (i = 2; i begin dedsec[error_location2] = dedsec[error_location2] ^ data[(error_location2-1)*16+i]; end end // Finally, after recalculating the error bit in the row/col, // recalculate the faulty zeroth dedsec bit. dedsec[0]=dedsec[1]^dedsec[2]; for ( i=3 ; i begin dedsec[0] = dedsec[0] ^ dedsec[i]; end end else // Finally, it is the normal case where the dedsec bit // themselves has no error and only 1 data bit have error begin // If error_loc2>error_loc1 swap them to facilitate the program if ( error_location2 > error_location1 ) begin temp = error_location2; error_location2 = error_location1; error_location1 = temp; end // Calculate the error bit location and invert it l = (error_location2 - 1) * 16 + (error_location1 - 9); data[l] = ~data[l]; end end endtask endmodule
