Writing literal addresses in your redcode can be difficult to read and maintain.

Consider the following code:

dat #1, #2
mov -1, 10

The mov instruction copies the previous dat instruction to a new location. Suppose we now add a new line in between the dat and mov instructions:

dat #1, #2
spl 5       ; <- a new instruction
mov -1, 10

The mov instruction now copies the spl rather than the dat as we originally intended.

The get around these problems and generally improve readability of your redcode you can use labels.

Labels allow aliases to be defined for addresses within your code. To specify a label, enter its name in front of the instruction's opcode. A label name must begin with an alphabetic character (a-z) or an underscore. The rest of the label can contain alphanumeric characters or underscores.

Optionally, a colon : may be placed after the label name.

Legal label declarations include:


Once a label is declared, it can be used throughout your redcode in place of an operand's number as demonstrated below.

bmb: dat     #4, #0
top: add.ab bmb, bmb
     mov.i  bmb, @bmb
     jmp top

Here we have declared two labels bmb and top. The bmb label refers to the dat instruction's address and top to the add instruction's address.

When this program is parsed, the parser will replace all references to the label with its address relative to the instruction where it is used. The above code, when parsed will look like this:

DAT.F #4, #0
ADD.AB $-1, $-1   ; <- here bmb was replaced with -1
MOV.I $-2, @-2    ; <- here bmb was replaced with -2
JMP.B $-2, $0     ; <- here top was replaced with -2

Notice that on the add instruction, the refence to bmb was replaced with -1 since the dat instruction is one position above the add instruction. However on the mov instruction bmb was replaced with -2 since the dat instruction is two positions above the mov instruction.

It is possible to define multiple labels for the same address, either by placing each label declaration on the same line or on multiple lines before the instruction they refer to:

mov 0, 1

Here both label and another refer to the mov instruction's address.