1 | module cic_filter
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2 | #(
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3 | parameter size = 3, // number of channels
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4 | parameter width = 12 // bit width of the input data (unsigned)
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5 | )
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6 | (
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7 | input wire clock, frame, reset,
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8 | input wire [size*width-1:0] inp_data,
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9 | output wire [size*widthr-1:0] out_data,
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10 | output wire [size*widthr-1:0] out_data2,
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11 | output wire [size*widthr-1:0] out_data3
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12 | );
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13 |
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14 | localparam widthr = width + 16;
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15 | /*
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16 | 4-bit LFSR with additional bits to keep track of previous values
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17 | */
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18 | reg [15:0] int_lfsr_reg, int_lfsr_next;
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19 |
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20 | reg int_wren_reg, int_wren_next;
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21 | reg int_flag_reg, int_flag_next;
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22 | reg [1:0] int_chan_reg, int_chan_next;
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23 | reg [2:0] int_case_reg, int_case_next;
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24 | reg [7:0] int_addr_reg, int_addr_next;
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25 |
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26 | wire [9:0] int_addr_wire;
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27 |
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28 | reg [size*widthr-1:0] acc_data_reg [3:0], acc_data_next [3:0];
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29 | reg [size*widthr-1:0] int_data_reg [12:0], int_data_next [12:0];
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30 |
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31 | wire [size*widthr-1:0] acc_data_wire [3:0], del_data_wire [1:0];
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32 |
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33 | integer i;
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34 | genvar j;
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35 |
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36 | generate
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37 | for (j = 0; j < size; j = j + 1)
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38 | begin : INT_DATA
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39 | assign acc_data_wire[0][j*widthr+widthr-1:j*widthr] = {{(widthr-width){1'b0}}, inp_data[j*width+width-1:j*width]};
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40 |
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41 | // -2*del_data_1 + del_data_2 + inp_data + result
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42 |
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43 | assign acc_data_wire[1][j*widthr+widthr-1:j*widthr] =
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44 | acc_data_reg[0][j*widthr+widthr-1:j*widthr]
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45 | + del_data_wire[1][j*widthr+widthr-1:j*widthr]
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46 | - {del_data_wire[0][j*widthr+widthr-1],del_data_wire[0][j*widthr+widthr-3:j*widthr], 1'b0};
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47 |
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48 | assign acc_data_wire[2][j*widthr+widthr-1:j*widthr] =
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49 | acc_data_reg[1][j*widthr+widthr-1:j*widthr]
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50 | + acc_data_reg[2][j*widthr+widthr-1:j*widthr];
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51 |
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52 | assign acc_data_wire[3][j*widthr+widthr-1:j*widthr] =
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53 | acc_data_reg[2][j*widthr+widthr-1:j*widthr]
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54 | + acc_data_reg[3][j*widthr+widthr-1:j*widthr];
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55 |
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56 | end
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57 | endgenerate
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58 |
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59 | cic_pipeline #(
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60 | .width(size*widthr)) cic_pipeline_unit (
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61 | .clock(clock),
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62 | .data(acc_data_reg[0]),
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63 | .rdaddress_a({int_addr_wire[9:8], int_addr_wire[3:0]}),
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64 | .rdaddress_b({int_addr_wire[9:8], int_addr_wire[7:4]}),
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65 | .wraddress(int_addr_reg),
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66 | .wren(int_wren_reg),
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67 | .qa(del_data_wire[0]),
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68 | .qb(del_data_wire[1]));
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69 |
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70 | lpm_mux #(
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71 | .lpm_size(4),
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72 | .lpm_type("LPM_MUX"),
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73 | .lpm_width(10),
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74 | .lpm_widths(2)) mux_unit_1 (
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75 | .sel(int_chan_next),
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76 | .data({
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77 | 2'd3, int_lfsr_reg[2*5+3:2*5], int_lfsr_reg[5+3:5],
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78 | 2'd2, int_lfsr_reg[2*4+3:2*4], int_lfsr_reg[4+3:4],
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79 | 2'd1, int_lfsr_reg[2*3+3:2*3], int_lfsr_reg[3+3:3],
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80 | 2'd0, int_lfsr_reg[2*3+3:2*3], int_lfsr_reg[3+3:3]}),
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81 | .result(int_addr_wire));
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82 |
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83 | always @(posedge clock)
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84 | begin
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85 | if (reset)
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86 | begin
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87 | int_wren_reg <= 1'b1;
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88 | int_flag_reg <= 1'b0;
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89 | int_chan_reg <= 2'd0;
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90 | int_case_reg <= 3'd0;
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91 | int_addr_reg <= 8'd0;
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92 | for(i = 0; i <= 3; i = i + 1)
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93 | begin
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94 | acc_data_reg[i] <= {(size*widthr){1'b0}};
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95 | end
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96 | for(i = 0; i <= 12; i = i + 1)
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97 | begin
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98 | int_data_reg[i] <= {(size*widthr){1'b0}};
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99 | end
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100 | int_lfsr_reg <= 16'd0;
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101 | end
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102 | else
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103 | begin
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104 | int_wren_reg <= int_wren_next;
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105 | int_flag_reg <= int_flag_next;
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106 | int_chan_reg <= int_chan_next;
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107 | int_case_reg <= int_case_next;
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108 | int_addr_reg <= int_addr_next;
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109 | for(i = 0; i <= 3; i = i + 1)
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110 | begin
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111 | acc_data_reg[i] <= acc_data_next[i];
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112 | end
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113 | for(i = 0; i <= 12; i = i + 1)
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114 | begin
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115 | int_data_reg[i] <= int_data_next[i];
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116 | end
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117 | int_lfsr_reg <= int_lfsr_next;
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118 | end
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119 | end
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120 |
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121 | always @*
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122 | begin
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123 | int_wren_next = int_wren_reg;
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124 | int_flag_next = int_flag_reg;
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125 | int_chan_next = int_chan_reg;
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126 | int_case_next = int_case_reg;
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127 | int_addr_next = int_addr_reg;
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128 | for(i = 0; i <= 3; i = i + 1)
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129 | begin
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130 | acc_data_next[i] = acc_data_reg[i];
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131 | end
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132 | for(i = 0; i <= 12; i = i + 1)
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133 | begin
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134 | int_data_next[i] = int_data_reg[i];
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135 | end
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136 | int_lfsr_next = int_lfsr_reg;
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137 |
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138 | case (int_case_reg)
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139 | 0:
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140 | begin
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141 | // write zeros
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142 | int_wren_next = 1'b1;
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143 | int_addr_next = 8'd0;
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144 | for(i = 0; i <= 3; i = i + 1)
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145 | begin
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146 | acc_data_next[i] = {(size*widthr){1'b0}};
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147 | end
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148 | for(i = 0; i <= 12; i = i + 1)
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149 | begin
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150 | int_data_next[i] = {(size*widthr){1'b0}};
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151 | end
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152 | int_case_next = 3'd1;
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153 | end
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154 | 1:
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155 | begin
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156 | // write zeros
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157 | int_addr_next = int_addr_reg + 8'd1;
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158 | if (&int_addr_reg)
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159 | begin
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160 | int_wren_next = 1'b0;
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161 | int_flag_next = 1'b0;
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162 | int_chan_next = 2'd0;
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163 | int_lfsr_next = 16'h7650;
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164 | int_case_next = 3'd2;
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165 | end
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166 | end
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167 | 2: // frame
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168 | begin
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169 | int_flag_next = 1'b0;
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170 | if (frame)
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171 | begin
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172 | int_wren_next = 1'b1;
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173 |
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174 | int_addr_next = {4'd0, int_lfsr_reg[3:0]};
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175 |
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176 | // set read addr for 2nd pipeline
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177 | int_chan_next = 2'd1;
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178 |
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179 | // prepare registers for 1st sum
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180 | acc_data_next[0] = acc_data_wire[0];
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181 | acc_data_next[1] = int_data_reg[0];
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182 | acc_data_next[2] = int_data_reg[1];
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183 | acc_data_next[3] = int_data_reg[2];
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184 |
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185 | int_case_next = 3'd3;
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186 | end
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187 | if (int_flag_reg) // register 4th sum
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188 | begin
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189 | // register 4th sum
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190 | int_data_next[9] = acc_data_wire[1];
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191 | int_data_next[10] = acc_data_wire[2];
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192 | int_data_next[11] = acc_data_wire[3];
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193 | end
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194 | end
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195 | 3: // 1st sum
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196 | begin
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197 | int_addr_next = {4'd1, int_lfsr_reg[3:0]};
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198 |
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199 | // set read addr for 3rd pipeline
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200 | int_chan_next = 2'd2;
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201 |
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202 | // prepare registers for 2nd sum
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203 | acc_data_next[0] = int_data_reg[2];
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204 | acc_data_next[1] = int_data_reg[3];
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205 | acc_data_next[2] = int_data_reg[4];
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206 | acc_data_next[3] = int_data_reg[5];
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207 |
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208 | // register 1st sum
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209 | int_data_next[0] = acc_data_wire[1];
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210 | int_data_next[1] = acc_data_wire[2];
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211 | int_data_next[2] = acc_data_wire[3];
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212 |
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213 | int_case_next = 3'd4;
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214 | end
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215 | 4: // 2nd sum
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216 | begin
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217 | int_addr_next = {4'd2, int_lfsr_reg[3:0]};
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218 |
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219 | // set read addr for 4th pipeline
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220 | int_chan_next = 2'd3;
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221 |
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222 | // prepare registers for 3rd sum
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223 | acc_data_next[0] = int_data_reg[5];
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224 | acc_data_next[1] = int_data_reg[6];
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225 | acc_data_next[2] = int_data_reg[7];
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226 | acc_data_next[3] = int_data_reg[8];
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227 |
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228 | // register 2nd sum
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229 | int_data_next[3] = acc_data_wire[1];
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230 | int_data_next[4] = acc_data_wire[2];
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231 | int_data_next[5] = acc_data_wire[3];
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232 |
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233 | int_lfsr_next = {int_lfsr_reg[14:0], int_lfsr_reg[2] ~^ int_lfsr_reg[3]};
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234 |
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235 | int_case_next = 3'd5;
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236 | end
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237 | 5: // 3rd sum
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238 | begin
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239 | int_flag_next = 1'b1;
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240 |
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241 | int_addr_next = {4'd3, int_lfsr_reg[4:1]};
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242 |
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243 | // set read addr for 1st pipeline
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244 | int_chan_next = 2'd0;
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245 |
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246 | // prepare registers for 4th sum
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247 | acc_data_next[0] = int_data_reg[8];
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248 | acc_data_next[1] = int_data_reg[9];
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249 | acc_data_next[2] = int_data_reg[10];
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250 | acc_data_next[3] = int_data_reg[11];
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251 |
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252 | // register 3rd sum
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253 | int_data_next[6] = acc_data_wire[1];
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254 | int_data_next[7] = acc_data_wire[2];
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255 | int_data_next[8] = acc_data_wire[3];
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256 |
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257 | // register 4th output
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258 | int_data_next[12] = int_data_reg[11];
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259 |
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260 | int_case_next = 3'd2;
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261 | end
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262 | default:
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263 | begin
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264 | int_case_next = 3'd0;
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265 | end
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266 | endcase
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267 | end
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268 |
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269 | assign out_data = int_data_reg[5];
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270 | assign out_data2 = int_data_reg[8];
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271 | assign out_data3 = int_data_reg[12];
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272 |
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273 | endmodule
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