Verilog之$sreadmemb

1　　Memories 

　Memories file format is shown below, the address is specified as @ <address> in hexadecimal.

        　　@003
       　　 00000011
       　　 00000100
       　　 00000101
        　　00000110
       　　 00000111
     　　   00001000
      　　  00001001

　With the above file it can be seen if the memory is large it would become very tedious to work out the address of a specific byte, so it is normally a good idea to use milestones along the memory file, so a larger file may look something like the following:

     　　   @003
    　　    00000011
       　　 00000100
       　　 00000101
       　　 @006
      　　  00000110
       　　 00000111
    　　    @008
      　　  00001000
        　　00001001

 　or if the data is contiguous, omit the address entirely.

 

2　　Syntax: 

　$readmemb ("<file_name>", <memory_name>"); 
　$readmemb ("<file_name>", <memory_name>, memory_start"); 
　$readmemb ("<file_name>", <memory_name>, memory_start, memory_finish");

　The memory_start and memory_finish are optional.

 

3　　　Example

　Now that a memory file exists to access it, it has to be initialised for memory reading. 

module testmemory;
    reg [7:0] memory [9:0];
    integer   index;

    initial 
　　 begin
        $readmemb("mem.dat", memory);
        
        for(index = 0; index < 10; index = index + 1)
        $display("memory[%d] = %b", index[4:0], memory[index]);
     end
endmodule // testmemory   

　　with the file mem.data as

        1000_0001
        1000_0010
        0000_0000
        0000_0001
        0000_0010
        0000_0011
        0000_0100
        0000_0101
        0000_0110
        0000_0000