shithub: rgbds

ref: cad23465a5baefe473fca9b117be6e853065df34
dir: /src/rgbds.5/

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.\"
.\" This file is part of RGBDS.
.\"
.\" Copyright (c) 2017-2018, Antonio Nino Diaz and RGBDS contributors.
.\"
.\" SPDX-License-Identifier: MIT
.\"
.Dd January 26, 2018
.Dt RGBDS 5
.Os RGBDS Manual
.Sh NAME
.Nm rgbds
.Nd object file format documentation
.Sh DESCRIPTION
This is the description of the object files used by
.Xr rgbasm 1
and
.Xr rgblink 1 .
Please, note that the specifications may change.
This toolchain is in development and new features may require adding more
information to the current format, or modifying some fields, which would break
compatibility with older versions.
.Pp
.Sh FILE STRUCTURE
The following types are used:
.Pp
.Ar LONG
is a 32‐bit integer stored in little‐endian format (Intel).
.Ar BYTE
is an 8‐bit integer.
.Ar STRING
is a 0‐terminated string of
.Ar BYTE .
.Pp
.Bd -literal
; Header

BYTE    ID[4]            ; "RGB6"
LONG    NumberOfSymbols  ; The number of symbols used in this file
LONG    NumberOfSections ; The number of sections used in this file

; Symbols

REPT    NumberOfSymbols   ; Number of symbols defined in this object file.

    STRING  Name          ; The name of this symbol. Local symbols are stored
                          ; as "Scope.Symbol".

    BYTE    Type          ; 0 = LOCAL symbol only used in this file.
                          ; 1 = IMPORT this symbol from elsewhere
                          ; 2 = EXPORT this symbol to other objects.

    IF      Type != 1     ; If symbol is defined in this object file.

        STRING  FileName  ; File where the symbol is defined.

        LONG    LineNum   ; Line number in the file where the symbol is defined.

        LONG    SectionID ; The section number (of this object file) in which
                          ; this symbol is defined. If it doesn't belong to any
                          ; specific section (like a constant), this field has
                          ; the value -1.

        LONG    Value     ; The symbols value. It's the offset into that
                          ; symbol's section.

    ENDC

ENDR

; Sections

REPT NumberOfSections
    STRING  Name  ; Name of the section

    LONG    Size  ; Size in bytes of this section

    BYTE    Type  ; 0 = WRAM0
                  ; 1 = VRAM
                  ; 2 = ROMX
                  ; 3 = ROM0
                  ; 4 = HRAM
                  ; 5 = WRAMX
                  ; 6 = SRAM
                  ; 7 = OAM

    LONG    Org   ; Address to fix this section at. -1 if the linker should
                  ; decide (floating address).

    LONG    Bank  ; Bank to load this section into. -1 if the linker should
                  ; decide (floating bank). This field is only valid for ROMX,
                  ; VRAM, WRAMX and SRAM sections.

    LONG    Align ; Alignment of this section, expressed as 1 << align. 1 if
                  ; not specified.

    IF      (Type == ROMX) || (Type == ROM0) ; Sections that can contain data.

        BYTE    Data[Size]      ; Raw data of the section.

        LONG    NumberOfPatches ; Number of patches to apply.

        ; These types of sections may have patches

        REPT    NumberOfPatches

            STRING  SourceFile   ; Name of the source file (for printing error
                                 ; messages).

            LONG    Line         ; The line of the source file.

            LONG    Offset       ; Offset into the section where patch should
                                 ; be applied (in bytes).

            BYTE    Type         ; 0 = BYTE patch.
                                 ; 1 = little endian WORD patch.
                                 ; 2 = little endian LONG patch.
                                 ; 3 = JR offset value BYTE patch.

            LONG    RPNSize      ; Size of the buffer with the RPN.
                                 ; expression.

            BYTE    RPN[RPNSize] ; RPN expression. Definition below.

        ENDR

    ENDC

ENDR
.Ed
.Ss RPN DATA
Expressions in the object file are stored as RPN.
This is an expression of the form
.Do 2 5 + Dc .
This will first push the value
.Do 2 Dc to the stack.
Then
.Do 5 Dc .
The
.Do + Dc operator pops two arguments from the stack, adds them, and then pushes
the result on the stack, effectively replacing the two top arguments with their
sum.
In the RGB format, RPN expressions are stored as BYTEs with some bytes being
special prefixes for integers and symbols.
.Pp
.Bl -column -offset indent ".Sy String" ".Sy String"
.It Sy Value Ta Sy Meaning
.It Li $00 Ta Li + operator
.It Li $01 Ta Li - operator
.It Li $02 Ta Li * operator
.It Li $03 Ta Li / operator
.It Li $04 Ta Li % operator
.It Li $05 Ta Li unary -
.It Li $10 Ta Li | operator
.It Li $11 Ta Li & operator
.It Li $12 Ta Li ^ operator
.It Li $13 Ta Li unary ~
.It Li $21 Ta Li && comparison
.It Li $22 Ta Li || comparison
.It Li $23 Ta Li unary !
.It Li $30 Ta Li == comparison
.It Li $31 Ta Li != comparison
.It Li $32 Ta Li > comparison
.It Li $33 Ta Li < comparison
.It Li $34 Ta Li >= comparison
.It Li $35 Ta Li <= comparison
.It Li $40 Ta Li << operator
.It Li $41 Ta Li >> operator
.It Li $50 Ta Li BANK(symbol),
a
.Ar LONG
Symbol ID follows.
.It Li $51 Ta Li BANK(section_name),
a null-terminated string follows.
.It Li $52 Ta Li Current BANK() .
.It Li $60 Ta Li HRAMCheck.
Check if the value is in HRAM, AND it with 0xFF.
.It Li $80 Ta Ar LONG
integer follows.
.It Li $81 Ta Ar LONG
Symbol ID follows.
.El
.Pp
.Sh SEE ALSO
.Xr rgbasm 1 ,
.Xr rgblink 1 ,
.Xr rgbds 7 ,
.Xr gbz80 7
.Sh HISTORY
.Nm rgbds
was originally written by Carsten S\(/orensen 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
.Lk https://github.com/rednex/rgbds .