大端 m
m[ a +: b ] == m[ (a+b-1) : a ]
m[ a -: b ] == m[ a : (a-b+1) ]
小端 n
n[ a +: b ] == n[ a : (a+b-1) ]
n[ a -: b ] == n[ (a-b+1) : a ]
module top;
`timescale 10ns/1ns
reg [31:0] big_vect = 'h12345678;
reg [0:31] little_vect = 'h87654321;
reg [63:0] dword;
integer sel;
initial
begin
#100
$display("1. big_vect = 0x%h, big_vect[0 +:8] is %h, and big_vect[7 -:8] is %h ", big_vect, big_vect[0 +:8], big_vect[7 -:8] );
if ( big_vect[0 +:8] == big_vect[7 : 0])begin $display(" big_vect[0 +:8] == big_vect[7 : 0]"); end
if (little_vect[0 +:8] == little_vect[0 : 7])begin $display("little_vect[0 +:8] == little_vect[0 : 7]"); end
if ( big_vect[15 -:8] == big_vect[15 : 8])begin $display(" big_vect[15 -:8] == big_vect[15 : 8]"); end
if (little_vect[15 -:8] == little_vect[8 :15])begin $display("little_vect[15 -:8] == little_vect[8 :15]"); end
if (sel >0 && sel < 8) dword[8*sel +:8] = big_vect[7:0]; // Replace the byte selected.
// 注意： big_vect[0:7] 引用错误，同理little_vect[15:8] 也是引用错误。
// if ( big_vect[0 +:8] == big_vect[0 : 7])begin end
end
endmodule
输出
# 1. big_vect = 0x12345678, big_vect[0 +:8] is 78, and big_vect[7 -:8] is 78 # big_vect[0 +:8] == big_vect[7 : 0] # little_vect[0 +:8] == little_vect[0 : 7] # big_vect[15 -:8] == big_vect[15 : 8] # little_vect[15 -:8] == little_vect[8 :15]