2019/03/20 追記：メモリベースFIRフィルタを修正しました。
2019/03/06 追記：メモリベースFIRフィルタを修正しました。
2018/07/21 追記：係数のビット数を変更。
2018/07/18 追記：Logic Elementsを節約できるメモリベースFIRフィルタに変更。
2018/07/17 追記：タップ数を変更。
FM復調した384kHzの信号をI2S DAC用の48kHzの信号に間引くため、FIRフィルタの出力部分に1/8間引き機能を追加しました。
`timescale 1ns/1ns module MyMEMLPF8 #( parameter RATE = 8, parameter DATA_WIDTH = 10 ) ( input wire clk, input wire reset_n, input wire signed [DATA_WIDTH-1:0] ast_sink_data, input wire ast_sink_valid, input wire [1:0] ast_sink_error, output reg signed [DATA_WIDTH-1:0] ast_source_data, output reg ast_source_valid, output wire [1:0] ast_source_error ); localparam NUM_TAPS = 199; localparam H_WIDTH = 16; localparam Y_WIDTH = H_WIDTH + DATA_WIDTH - 1; // RAM 16x256 localparam RAM_NUM_ADDRS = 256; integer i; reg signed [H_WIDTH-1:0] h[0:NUM_TAPS-1]; wire signed [DATA_WIDTH-1:0] x; reg signed [Y_WIDTH-1:0] y; wire [7:0] raddr; reg [7:0] waddr; reg [7:0] last_waddr; reg [8:0] cnt; reg [7:0] deci_cnt; // Normalized Frequency: 0.042 initial begin h[0] = 7; h[1] = 6; h[2] = 4; h[3] = 2; h[4] = -1; h[5] = -3; h[6] = -6; h[7] = -8; h[8] = -10; h[9] = -11; h[10] = -12; h[11] = -12; h[12] = -11; h[13] = -9; h[14] = -7; h[15] = -3; h[16] = 2; h[17] = 6; h[18] = 11; h[19] = 16; h[20] = 20; h[21] = 24; h[22] = 25; h[23] = 25; h[24] = 23; h[25] = 19; h[26] = 13; h[27] = 5; h[28] = -4; h[29] = -14; h[30] = -25; h[31] = -34; h[32] = -43; h[33] = -49; h[34] = -51; h[35] = -51; h[36] = -46; h[37] = -37; h[38] = -24; h[39] = -8; h[40] = 10; h[41] = 29; h[42] = 49; h[43] = 67; h[44] = 81; h[45] = 91; h[46] = 95; h[47] = 92; h[48] = 82; h[49] = 65; h[50] = 42; h[51] = 12; h[52] = -21; h[53] = -56; h[54] = -89; h[55] = -120; h[56] = -144; h[57] = -160; h[58] = -166; h[59] = -160; h[60] = -141; h[61] = -110; h[62] = -67; h[63] = -16; h[64] = 42; h[65] = 102; h[66] = 160; h[67] = 212; h[68] = 253; h[69] = 280; h[70] = 288; h[71] = 276; h[72] = 242; h[73] = 187; h[74] = 111; h[75] = 19; h[76] = -85; h[77] = -194; h[78] = -302; h[79] = -401; h[80] = -482; h[81] = -537; h[82] = -559; h[83] = -542; h[84] = -481; h[85] = -374; h[86] = -220; h[87] = -21; h[88] = 218; h[89] = 491; h[90] = 789; h[91] = 1102; h[92] = 1417; h[93] = 1724; h[94] = 2009; h[95] = 2261; h[96] = 2469; h[97] = 2624; h[98] = 2720; h[99] = 2752; h[100] = 2720; h[101] = 2624; h[102] = 2469; h[103] = 2261; h[104] = 2009; h[105] = 1724; h[106] = 1417; h[107] = 1102; h[108] = 789; h[109] = 491; h[110] = 218; h[111] = -21; h[112] = -220; h[113] = -374; h[114] = -481; h[115] = -542; h[116] = -559; h[117] = -537; h[118] = -482; h[119] = -401; h[120] = -302; h[121] = -194; h[122] = -85; h[123] = 19; h[124] = 111; h[125] = 187; h[126] = 242; h[127] = 276; h[128] = 288; h[129] = 280; h[130] = 253; h[131] = 212; h[132] = 160; h[133] = 102; h[134] = 42; h[135] = -16; h[136] = -67; h[137] = -110; h[138] = -141; h[139] = -160; h[140] = -166; h[141] = -160; h[142] = -144; h[143] = -120; h[144] = -89; h[145] = -56; h[146] = -21; h[147] = 12; h[148] = 42; h[149] = 65; h[150] = 82; h[151] = 92; h[152] = 95; h[153] = 91; h[154] = 81; h[155] = 67; h[156] = 49; h[157] = 29; h[158] = 10; h[159] = -8; h[160] = -24; h[161] = -37; h[162] = -46; h[163] = -51; h[164] = -51; h[165] = -49; h[166] = -43; h[167] = -34; h[168] = -25; h[169] = -14; h[170] = -4; h[171] = 5; h[172] = 13; h[173] = 19; h[174] = 23; h[175] = 25; h[176] = 25; h[177] = 24; h[178] = 20; h[179] = 16; h[180] = 11; h[181] = 6; h[182] = 2; h[183] = -3; h[184] = -7; h[185] = -9; h[186] = -11; h[187] = -12; h[188] = -12; h[189] = -11; h[190] = -10; h[191] = -8; h[192] = -6; h[193] = -3; h[194] = -1; h[195] = 2; h[196] = 4; h[197] = 6; h[198] = 7; end assign ast_source_error = 2'b00; always @(posedge clk) begin if (~reset_n) begin waddr