if语句法
1 //8线-3线优先编码器设计(74LS148) 2 // 3 //EI | A7 A6 A5 A4 A3 A2 A1 A0 | Y2 Y1 Y0 GS EO 4 //0 | 0 x x x x x x x | 0 0 0 0 1 5 //0 | 1 0 x x x x x x | 0 0 1 0 1 6 //0 | 1 1 0 x x x x x | 0 1 0 0 1 7 //0 | 1 1 1 0 x x x x | 0 1 1 0 1 8 //0 | 1 1 1 1 0 x x x | 1 0 0 0 1 9 //0 | 1 1 1 1 1 0 x x | 1 0 1 0 1 10 //0 | 1 1 1 1 1 1 0 x | 1 1 0 0 1 11 //0 | 1 1 1 1 1 1 1 0 | 1 1 1 0 1 12 //0 | 1 1 1 1 1 1 1 1 | 1 1 1 1 0 13 //1 | x x x x x x x x | 1 1 1 1 1 14 15 16 module encoder_83 (din, EI, GS, EO, dout); 17 input [7:0] din; //编码输入端data_in,低电平有效 18 input EI; //使能输入端EI(选通输入端),EI为 0 时芯片工作,即允许编码 19 output [2:0] dout; //编码输出端data_out 20 output GS; //片优先编码输出端,优先编码器工作工作状态标志GS,低电平有效 21 output EO; //使能输出端EO(选通输出端) 22 reg [2:0] dout; 23 reg GS, EO; 24 always @(din or EI) 25 if(EI) begin dout <= 3'b111; GS <= 1; EO <= 1; end //所有输出端被锁存在高电平 26 else if (din[7] == 0) begin dout <= 3'b000; GS <= 0; EO <= 1; end