RGBLINK(5)

NAME
rgblink - linker script file format

DESCRIPTION
The linker script is an external file that allows the user to specify the order of sections at link time and in a centralized manner.

A linker script consists of a series of bank declarations, each optionally followed by a list of section names (in double quotes) or commands. All reserved keywords (bank types and command names) are case-insensitive; all section names are case-sensitive.

Any line can contain a comment starting with ‘’; that ends at the end of the line.

    ; This line is a comment
    ROMX $F            ; start a bank
      "Some functions" ; a section name
      ALIGN 8          ; a command
      "Some array"
    WRAMX 2            ; start another bank
      org $d123        ; another command
      "Some variables"

Numbers can be in decimal or hexadecimal format (the prefix is ‘$’). It is an error if any section name or command is found before setting a bank.

Files can be included by using the INCLUDE keyword, followed by a string with the path of the file that has to be included.

The possible bank types are: ROM0, ROMX, VRAM, SRAM, WRAM0, WRAMX, OAM and HRAM. Unless there is a single bank, which can occur with types ROMX, VRAM, SRAM and WRAMX, it is needed to specify a bank number after the type.

Section names in double quotes support the same character escape sequences as strings in rgbasm(5), specifically ‘\\’, ‘\"’, ‘\n’, ‘\r’, and ‘\t’. Other backslash escape sequences in rgbasm(5) are only relevant to assembly code and do not apply in section names.

When a new bank statement is found, sections found after it will be placed right from the beginning of that bank. If the linker script switches to a different bank and then comes back to a previous one, it will continue from the last address that was used.

The only three commands are ORG, ALIGN, and DS:

•   ORG sets the address in which new sections will be placed. It can not be lower than the current address.

•   ALIGN will increase the address until it is aligned to the specified boundary (it tries to set to 0 the number of bits specified after the command: ‘ALIGN 8’ will align to $100).

•   DS will increase the address by the specified non-negative amount.

Note: The bank, alignment, address and type of sections can be specified both in the source code and in the linker script. For a section to be able to be placed with the linker script, the bank, address and alignment must be left unassigned in the source code or be compatible with what is specified in the linker script. For example, ‘ALIGN[8]’ in the source code is compatible with ‘ORG $F00’ in the linker script.

SEE ALSO
rgbasm(1), rgblink(1), rgbfix(1), rgbds(5), rgbds(7)

HISTORY
rgblink was originally written by Carsten Sørensen as part of the ASMotor package, and was later packaged in RGBDS by Justin Lloyd. It is now maintained by a number of contributors at https://github.com/gbdev/rgbds.