kopia lustrzana https://github.com/hoglet67/RGBtoHDMI
121 wiersze
4.4 KiB
Plaintext
121 wiersze
4.4 KiB
Plaintext
This chapter describes the O65 binary relocation format V1.3 for the 6502
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family, as defined by Andre Fachat on 6502.org.
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Option @option{-Fo65} outputs object files suitable for another linker pass,
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while @option{-Fo65exe} outputs executable files for an O65 loader. The
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difference is just a flag which declares the file being an object, and
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vasm will make sure that the load-addresses of sections in an executable
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will be consecutive and do not overlay.
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@section Legal
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This module is written in 2021 by Frank Wille and
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is covered by the vasm copyright without modifications.
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@section Additional options for this module
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@table @option
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@item -bss=<addr>
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Sets a start address for the @code{bss} section.
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@item -data=<addr>
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Sets a start address for the @code{data} section.
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@item -fopts
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Enable informational header options, generated by the assembler:
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file name, assembler name and version, creation date.
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@item -foauthor=<name>
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Write author's name to the header options.
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@item -foname=<name>
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Write file name to the header options. Overwrites the real file
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name, which would be set by @option{-fopts}.
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@item -paged
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Make the output file use paged alignment and simplified paged
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relocations.
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@item -secalign=<align>
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Set minimum alignment for all sections as number of least significant
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bits which have to be zero. @code{align} may be 0, 1, 2, 8.
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The default behaviour is to use the maximum alignment given by the
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input sections.
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@item -stack=<stacksize>
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Store required stack size in the header.
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@item -text=<addr>
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Sets a start address for the @code{text} section.
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@item -zero=<addr>
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Sets a start address for the @code{zero} (zero/direct page) section.
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@end table
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These options are valid for the @code{o65exe} module only:
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@table @option
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@item -bsszero
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Set a flag in the header which requests automatic clearing of the
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@code{bss} section.
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@end table
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@section General
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This output module outputs the @code{o65} object file and @code{o65exe}
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executable file format for 6502-family processors and the 65816.
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The processor type is determined by the selected CPU of the active backend
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and stored in the header.
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The @code{o65exe} module generates executable files for a o65-loader,
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which is present in some 6502 operating systems (e.g. Lunix, SMOS, OS/A65).
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Unresolved symbols are allowed in o65 object- and executable-files.
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In the latter case the o65-loader is responsible to resolve them.
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Common symbols, weak symbol and most relocation types, except absolute
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addresses, are not supported by o65.
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The o65 format recognizes four different sections by their attributes
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or name:
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@itemize @minus
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@item text, sections which have executable code and/or are not
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writable (@code{acrx}).
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@item data, sections which have initialized data and may be read and
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written (@code{adrw}).
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@item bss, sections which have unitialized data and may be read and
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written (@code{aurw}).
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@item zero, sections which have uninitialized data, may be read
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and written, and do not have the string @code{"bss"} anywhere in
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their name (@code{aurw}).
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@end itemize
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Up to two absolute sections (@code{ORG} directive) can be stored in
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the @code{text} and @code{data} slots, in the order of occurence.
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@section Restrictions
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Currently the @code{o65}/@code{o65exe} output module is only intended to
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work with the @code{6502} cpu module and will abort when used otherwise.
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It supports all relocation types defined by o65, which are:
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@itemize @minus
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@item 0x20: absolute, 8-bit value or low-byte of 16-bit address
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@item 0x40: absolute, 8-bit high-byte of 16-bit address
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@item 0x80: absolute, 16-bit address
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@item 0xa0: absolute, 8-bit segment-byte of 24-bit address
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@item 0xc0: absolute, 24-bit address
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@end itemize
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Common or weak symbols are not supported.
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@section Known Problems
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Some known problems of this module at the moment:
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@itemize @minus
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@item Needs a better way to set start addresses for the sections
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in the assembler.
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@end itemize
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@section Error Messages
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This module has the following error messages:
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@itemize @minus
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@item 3004: section attributes <attr> not supported
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@item 3008: output module doesn't allow multiple sections of the same type (%s)
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@item 3011: weak symbol <%s> not supported by output format, treating as global
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@item 3015: file option %d max size exceeded: %lu
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@end itemize
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