Verilog：不支持程序连续分配注册

Question

    input [31:0] write_data;
    input [4:0]  write_reg;
    reg [31:0] registers [31:0];

always @(*) 
     assign registers[write_reg] = write_data;

I have a 32-bit input write_data , which i want to an assign corresponding index which i get from write reg.Error says you cant do continuous assignment which i think causes by always@(*) but if i remove that

It says object "registers" on left-hand side of assignment must have a net type and its another error.

Answer 1

You need to synchronously assign to registers. Because the synthesizer parses it and routes to a physical register (ie flip-flop)

always @(posedge clk) 
    my_reg = my_data;

Answer 2

assign inside an always block is the procedural assignment . It is not synthesizable and should not be used. It is there for very special modeling cases.

continuous assignment , or assign outside the always block is there for connecting nets and used all over the places. lhs of such an assignment must be a net type, ie wire . it cannot be a reg.

On the other hand all lhs in always blocks must be of 'reg' type.

what you had to do in your case was to remove the keyword assign :

input [31:0] write_data;
input [4:0]  write_reg;
reg [31:0] registers [31:0];

always @(*) 
     registers[write_reg] = write_data;