如何在Verilog中同时使用inout和reg
我有以下代码:如何在Verilog中同时使用inout和reg,verilog,Verilog,我有以下代码: module s(clock, direction, readWrite, LA1, LA2, LA3, LA4, LD1, LD2, LD3, LD4, RA1, RA2, RA3, RA4, RD1, RD2, RD3, RD4); // parameters input clock, direction, readWrite; inout reg [7:0] LD1, LD2, LD3, LD4, RD1, RD2, RD3, RD4; inout reg [1
module s(clock, direction, readWrite, LA1, LA2, LA3, LA4, LD1, LD2, LD3, LD4, RA1, RA2, RA3, RA4, RD1, RD2, RD3, RD4);
// parameters
input clock, direction, readWrite;
inout reg [7:0] LD1, LD2, LD3, LD4, RD1, RD2, RD3, RD4;
inout reg [11:0] LA1, LA2, LA3, LA4, RA1, RA2, RA3, RA4;
// code
always @(posedge clock) begin
if(direction==1) begin // left to right
assign RA1 = LA1 | LA2 | LA3 | LA4;
assign RD1 = LD1 | LD2 | LD3 | LD4;
assign { RA2, RA3, RA4 } = RA1;
assign { RD2, RD3, RD4 } = RD1;
end else begin
if(direction==1) begin // right to left
assign LA1 = RA1 | RA2 | RA3 | RA4;
assign LD1 = RD1 | RD2 | RD3 | RD4;
assign { LA2, LA3, LA4 } = LA1;
assign { LD2, LD3, LD4 } = LD1;
end
end
end
endmodule
但是,在第二行,“inout reg[7:0]LD1,…”声明在VeritakWin 3.84F中抛出了一个语法错误。(Veritak允许同时使用“output reg”,因为我的程序中给定代码之后有一个类似的代码)。如果删除“reg”,则在分配行中会出现错误。如果我删除“inout”,我显然会得到一个错误。我甚至尝试删除“assign”关键字,并将“=”替换为“
inout
端口不能是reg
类型。用于将值分配给inout
端口的assign
类型称为过程连续分配,但这种类型的端口不允许这样做。您必须改用连续赋值。在代码中:
module s(clock, direction, readWrite, LA1, LA2, LA3, LA4, LD1, LD2, LD3, LD4, RA1, RA2, RA3, RA4, RD1, RD2, RD3, RD4);
// parameters input clock, direction, readWrite;
inout [7:0] LD1, LD2, LD3, LD4, RD1, RD2, RD3, RD4;
inout [11:0] LA1, LA2, LA3, LA4, RA1, RA2, RA3, RA4;
// left to right
assign RA1 = (direction) ? (LA1 | LA2 | LA3 | LA4) : 'bz;
assign RD1 = (direction) ? (LD1 | LD2 | LD3 | LD4) : 'bz;
assign { RA2, RA3, RA4 } = (direction) ? RA1 : 'bz;
assign { RD2, RD3, RD4 } = (direction) ? RD1 : 'bz;
// right to left
assign LA1 = (!direction) ? (RA1 | RA2 | RA3 | RA4) : 'bz;
assign LD1 = (!direction) ? (RD1 | RD2 | RD3 | RD4) : 'bz;
assign { LA2, LA3, LA4 } = (!direction) ? LA1 : 'bz;
assign { LD2, LD3, LD4 } = (!direction) ? LD1 : 'bz;
endmodule
请注意,您不能同时读取和写入inout
端口,因此在读取时会设置高阻抗值。inout端口是双向端口,意味着它是设计的某个部分的输入端口,也是设计的其他部分的输出端口,您不能为设计输出端口分配任何值,因为它们的值是直接从其他输入端口的值计算出来的inout
端口不能声明为reg
,因为它们可以用作输入端口(作为导线)或输出端口(作为reg或导线)。