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641 lines
20 KiB
Plaintext
641 lines
20 KiB
Plaintext
This chapter describes the oldstyle syntax module suitable
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for some 8-bit CPUs (6502, 680x, 68HC1x, Z80, etc.),
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which is available with the extension @code{oldstyle}.
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@section Legal
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This module is written in 2002-2020 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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This syntax module provides the following additional options:
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@table @option
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@item -autoexp
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Automatically export all non-local symbols, making them visible
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to other modules during linking.
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@item -dotdir
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Directives have to be preceded by a dot (@code{.}).
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@item -i
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Ignore everything after a blank in the operand field and treat it as a
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comment. This option is only available when the backend does not separate
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its operands with blanks as well.
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@item -noc
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Disable C-style constant prefixes.
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@item -noi
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Disable intel-style constant suffixes.
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@end table
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@section General Syntax
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Labels always start at the first column and may be terminated by a
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colon (@code{:}), but don't need to. In the last case the mnemonic
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needs to be separated from the label by whitespace (not required in
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any case, e.g. @code{=}).
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Local labels are preceded by '@code{.}' or terminated by '@code{$}'.
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For the rest, any alphanumeric character including '@code{_}' is allowed.
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Local labels are valid between two global label definitions.
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It is allowed, but not recommended, to refer to any local symbol starting with
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'@code{.}' in the source, by preceding its name with the name of the last
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global symbol, which was defined before it: @code{global_name.local_name}.
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The operands are separated from the mnemonic by whitespace. Multiple
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operands are separated by comma (@code{,}).
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Make sure that you don't define a label on the same line as a
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directive for conditional assembly (if, else, endif)! This is not supported.
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Some CPU backends may supported multiple statements (directives or
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mnemonics) per line, separated by a special character (e.g. @code{:} for Z80).
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Comments are introduced by the comment character @code{;}, or the first
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blank following the operand field when option @option{-i} was given.
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The rest of the line will be ignored.
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Example:
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@code{mylabel instr op1,op2 ;comment}
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In expressions, numbers starting with @code{$} are hexadecimal (e.g.
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@code{$fb2c}). For Z80 also @code{&} may be used as a hexadecimal prefix,
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but make sure to avoid conflicts with the and-operator (either by using
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parentheses or blanks).
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@code{%} introduces binary numbers (e.g. @code{%1100101}).
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Numbers starting with @code{@@} are assumed to be octal numbers, e.g.
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@code{@@237} (except for Z80, where it means binary).
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A special case is a digit followed by a @code{#}, which can be used to
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define an arbitrary base between 2 and 9 (e.g. @code{4#3012}).
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Intel-style constant suffixes are supported: @code{h} for hexadecimal,
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@code{d} for decimal, @code{o} or @code{q} for octal and @code{b} for
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binary. Hexadecimal intel-style constants must start with a digit (prepend
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@code{0}, when required).
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Also C-style prefixes are supported for hexadecimal (@code{0x}) and
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binary (@code{0b}).
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All other numbers starting with a digit are decimal, e.g. @code{1239}.
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@section Directives
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The following directives are supported by this syntax module (if the
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CPU- and output-module allow it):
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@table @code
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@item <symbol> = <expression>
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Equivalent to @code{<symbol> equ <expression>}.
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@item abyte <modifier>,<exp1>[,<exp2>,"<string1>"...]
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Write the integer or string constants into successive bytes
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of memory in the current section while modifying each expression
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(and string-character) by the modifier expression.
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When the modifier contains the special @code{._} symbol, then it
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is a placeholder for any expression from the line. Otherwise the
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modifier will be just added to each element.
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Any combination of integer and character string constants is permitted.
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@item addr <exp1>[,<exp2>...]
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Equivalent to @code{word <exp1>[,<exp2>...]}.
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@item align <bitcount>
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Insert as much zero bytes as required to reach an address where
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<bit_count> low order bits are zero. For example @code{align 2} would
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make an alignment to the next 32-bit boundary.
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@item asc <exp1>[,<exp2>,"<string1>"...]
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Equivalent to @code{byte <exp1>[,<exp2>,"<string1>"...]}.
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@item ascii <exp1>[,<exp2>,"<string1>"...]
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See @code{defm}.
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@item asciiz "<string1>"[,"<string2>"...]
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See @code{string}.
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@item assert <expression>[,<message>]
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Display an error with the optional <message> when the expression
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is false.
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@item binary <file>
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Inserts the binary contents of <file> into the object code at
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this position. The file will be searched first in the current
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directory, then in all paths defined by @option{-I} or @code{incdir}
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in the order of occurence.
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@item blk <exp>[,<fill>]
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Insert <exp> zero or <fill> bytes into the current section.
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@item blkw <exp>[,<fill>]
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Insert <exp> zero or <fill> 16-bit words into the current section,
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using the endianess of the target CPU.
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@item bsz <exp>[,<fill>]
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Equivalent to @code{blk <exp>[,<fill>]}.
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@item byt
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Increases the program counter by one.
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Equivalent to @code{blk 1,0}.
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@item byte <exp1>[,<exp2>,"<string1>"...]
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Assign the integer or string constant operands into successive
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bytes of memory in the current section. Any combination of integer
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and character string constant operands is permitted.
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@item data <exp1>[,<exp2>,"<string1>"...]
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Equivalent to @code{byte <exp1>[,<exp2>,"<string1>"...]}.
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@item db <exp1>[,<exp2>,"<string1>"...]
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Equivalent to @code{byte <exp1>[,<exp2>,"<string1>"...]}.
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@item dc <exp>[,<fill>]
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Equivalent to @code{blk <exp>[,<fill>]}.
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@item defb <exp1>[,<exp2>,"<string1>"...]
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Equivalent to @code{byte <exp1>[,<exp2>,"<string1>"...]}.
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@item defc <symbol> = <expression>
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Define a new program symbol with the name <symbol> and assign to it
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the value of <expression>. Defining <symbol> twice will cause
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an error.
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@item defl <exp1>[,<exp2>...]
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Assign the values of the operands into successive 32-bit integers
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of memory in the current section, using the endianess of the target
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CPU.
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@item defp <exp1>[,<exp2>...]
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Assign the values of the operands into successive 24-bit integers
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of memory in the current section, using the endianess of the target
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CPU.
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@item defm "string"
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Equivalent to @code{text "string"}.
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@item defw <exp1>[,<exp2>...]
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Equivalent to @code{word <exp1>[,<exp2>...]}.
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@item dfb <exp1>[,<exp2>,"<string1>"...]
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Equivalent to @code{byte <exp1>[,<exp2>,"<string1>"...]}.
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@item dfw <exp1>[,<exp2>...]
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Equivalent to @code{word <exp1>[,<exp2>...]}.
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@item defs <exp>[,<fill>]
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Equivalent to @code{blk <exp>[,<fill>]}.
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@item dend
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Ends an offset-section started by @code{dsect} and restores the
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previously active section.
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@item dephase
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Equivalent to @code{rend}.
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@item ds <exp>[,<fill>]
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Equivalent to @code{blk <exp>[,<fill>]}.
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@item dsb <exp>[,<fill>]
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Equivalent to @code{blk <exp>[,<fill>]}.
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@item dsect
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Starts an 'offset-section' (the original directive in ADE was called
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'dummy-section') which does not generate any code in the output file.
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Its only purpose is to define absolute labels. Within a @code{dsect}
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block you may use @code{org} directives to set a new offset, which
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defaults to zero for the first @code{dsect} otherwise. Following
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@code{dsect} sections continue with the last offset from the former.
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Such an offsect-section block is closed by the @code{dend} directive,
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which restores the previous 'real' section.
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@item dsw <exp>[,<fill>]
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Equivalent to @code{blkw <exp>[,<fill>]}.
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@item dw <exp1>[,<exp2>...]
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Equivalent to @code{word <exp1>[,<exp2>...]}.
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@item end
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Assembly will terminate behind this line.
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@item endif
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Ends a section of conditional assembly.
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@item el
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Equivalent to @code{else}.
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@item else
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Assemble the following lines when the previous @code{if}-condition
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was false.
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@item ei
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Equivalent to @code{endif}. (Not available for Z80 CPU)
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@item endm
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Ends a macro definition.
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@item endmac
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Ends a macro definition.
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@item endmacro
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Ends a macro definition.
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@item endr
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Ends a repetition block.
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@item endrep
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Ends a repetition block.
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@item endrepeat
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Ends a repetition block.
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@item endstruct
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Ends a structure definition.
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@item endstructure
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Ends a structure definition.
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@item <symbol> eq <expression>
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Equivalent to @code{<symbol> equ <expression>}.
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@item <symbol> equ <expression>
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Define a new program symbol with the name <symbol> and assign to it
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the value of <expression>. Defining <symbol> twice will cause
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an error.
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@item extern <symbol>[,<symbol>...]
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See @code{global}.
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@item even
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Aligns to an even address. Equivalent to @code{align 1}.
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@item fail <message>
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Show an error message including the <message> string. Do not generate
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an ouput file.
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@item fi
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Equivalent to @code{endif}.
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@item fill <exp>
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Equivalent to @code{blk <exp>,0}.
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@item fcb <exp1>[,<exp2>,"<string1>"...]
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Equivalent to @code{byte <exp1>[,<exp2>,"<string1>"...]}.
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@item fcc "<string>"
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Equivalent to @code{text}.
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@item fdb <exp1>[,<exp2>,"<string1>"...]
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Equivalent to @code{word <exp1>[,<exp2>...]}.
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@item global <symbol>[,<symbol>...]
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Flag <symbol> as an external symbol, which means that <symbol> is
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visible to all modules in the linking process. It may be either
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defined or undefined.
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@item if <expression>
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Conditionally assemble the following lines if <expression> is non-zero.
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@item ifdef <symbol>
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Conditionally assemble the following lines if <symbol> is defined.
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@item ifndef <symbol>
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Conditionally assemble the following lines if <symbol> is undefined.
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@item ifd <symbol>
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Conditionally assemble the following lines if <symbol> is defined.
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@item ifnd <symbol>
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Conditionally assemble the following lines if <symbol> is undefined.
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@item ifeq <expression>
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Conditionally assemble the following lines if <expression> is zero.
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@item ifne <expression>
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Conditionally assemble the following lines if <expression> is non-zero.
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@item ifgt <expression>
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Conditionally assemble the following lines if <expression> is
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greater than zero.
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@item ifge <expression>
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Conditionally assemble the following lines if <expression> is
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greater than zero or equal.
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@item iflt <expression>
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Conditionally assemble the following lines if <expression> is
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less than zero.
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@item ifle <expression>
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Conditionally assemble the following lines if <expression> is
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less than zero or equal.
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@item ifused <symbol>
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Conditionally assemble the following lines if <symbol> has been
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previously referenced in an expression or in a parameter of an opcode.
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Issue a warning, when <symbol> is already defined.
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Note that @code{ifused} does not work, when the symbol has only been
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used in the following lines of the source.
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@item incbin <file>[,<offset>[,<nbytes>]]
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Inserts the binary contents of <file> into the object code at
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this position. When <offset> is specified, then the given number
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of bytes will be skipped at the beginning of the file. The optional
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<nbytes> argument specifies the maximum number of bytes to be read
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from that file.
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The file will be searched first in the current directory, then in all
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paths defined by @option{-I} or @code{incdir} in the order of occurence.
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@item incdir <path>
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Add another path to search for include files to the list of
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known paths. Paths defined with @option{-I} on the command line are
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searched first.
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@item include <file>
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Include source text of <file> at this position. The include file
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will be searched first in the current directory, then in all
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paths defined by @option{-I} or @code{incdir} in the order of
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occurence.
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@item mac <name>
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Equivalent to @code{macro <name>}.
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@item list
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The following lines will appear in the listing file, if it was
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requested.
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@item local <symbol>[,<symbol>...]
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Flag <symbol> as a local symbol, which means that <symbol> is
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local for the current file and invisible to other modules in
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the linking process.
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@item macro <name>[,<argname>...]
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Defines a macro which can be referenced by <name>. The <name>
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may also appear on the left side of the @code{macro} directive,
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starting at the first column. The macro definition is closed
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by an @code{endm} directive. When calling a macro you may pass
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up to 9 arguments, separated by comma. Those arguments are
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referenced within the macro context as @code{\1} to @code{\9},
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or optionally by named arguments, which you have to specify in
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the operand.
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Argument @code{\0} is set to the macro's first qualifier
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(mnemonic extension), when given.
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The special argument @code{\@@} inserts an underscore followed by
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a six-digit unique id, useful for defining labels.
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@code{\()} may be used as a separator between the name of a macro
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argument and the subsequent text.
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@code{\<symbolname>} inserts the current decimal value of the absolute
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symbol @code{symbolname}.
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@item mdat <file>
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Equivalent to @code{incbin <file>}.
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@item nolist
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The following lines will not be visible in a listing file.
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@item org <expression>
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Sets the base address for the subsequent code. This is equivalent
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to @code{*=<expression>}.
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@item phase <expression>
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Equivalent to @code{rorg <expression>}.
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@item repeat <expression>
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Equivalent to @code{rept <expression>}.
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@item rept <expression>
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Repeats the assembly of the block between @code{rept} and @code{endr}
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<expression> number of times. <expression> has to be positive.
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@item reserve <exp>
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Equivalent to @code{blk <exp>,0}.
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@item rend
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Ends a @code{rorg} block of label relocation. Following labels will
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be based on @code{org} again.
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@item rmb <exp>[,<fill>]
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Equivalent to @code{blk <exp>[,<fill>]}. (Not available for 6502 CPU.)
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@item roffs <expression>
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Sets the program counter <expression> bytes behind the start of the
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current section. The new program counter must not be smaller than the
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current one. The space will be padded with zeros.
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@item rorg <expression>
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Relocate all labels between @code{rorg} and @code{rend} based on the
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new origin from @code{<expression>}.
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@item section <name>[,"<attributes>"]
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Starts a new section named <name> or reactivate an old one. If
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attributes are given for an already existing section, they must
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match exactly. The section's name will also be defined as a new
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symbol, which represents the section's start address.
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The "<attributes>" string may consist of the following characters:
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Section Contents:
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@table @code
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@item c
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section has code
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@item d
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section has initialized data
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@item u
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section has uninitialized data
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@item i
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section has directives (info section)
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@item n
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section can be discarded
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@item R
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remove section at link time
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@item a
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section is allocated in memory
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@end table
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Section Protection:
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@table @code
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@item r
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section is readable
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@item w
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section is writable
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@item x
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section is executable
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@item s
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section is sharable
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@end table
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@item <symbol> set <expression>
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Create a new symbol with the name <symbol> and assign
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the value of <expression>. If <symbol> is already assigned, it will
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contain a new value from now on.
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@item spc <exp>
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Equivalent to @code{blk <exp>,0}.
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@item str "<string1>"[,"<string2>"...]
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Like @code{text}, but adds a terminating carriage return (ASCII
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code 13).
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@item string "<string1>"[,"<string2>"...]
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Like @code{text}, but adds a terminating zero-byte.
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@item struct <name>
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Defines a structure which can be referenced by <name>. Labels within
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a structure definitation can be used as field offsets. They will be
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defined as local labels of @code{<name>} and can be referenced through
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@code{<name>.<label>}. All directives are allowed, but instructions will
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be ignored when such a structure is used. Data definitions can be used as
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default values when the structure is used as initializer. The structure
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name, <name>, is defined as a global symbol with the structure's size.
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A structure definition is ended by @code{endstruct}.
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@item structure <name>
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Equivalent to @code{struct <name>}.
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@item text "<string>"
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Places a single string constant operands into successive bytes of
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memory in the current section. The string delimiters may be any
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printable ASCII character.
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@item weak <symbol>[,<symbol>...]
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Flag <symbol> as a weak symbol, which means that <symbol> is
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visible to all modules in the linking process and may be replaced
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by any global symbol with the same name.
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When a weak symbol remains undefined its value defaults to 0.
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@item wor <exp1>[,<exp2>...]
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Equivalent to @code{word <exp1>[,<exp2>...]}.
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@item wrd
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Increases the program counter by two.
|
|
Equivalent to @code{blkw 1,0}.
|
|
|
|
@item word <exp1>[,<exp2>...]
|
|
Assign the values of the operands into successive 16-bit words
|
|
of memory in the current section, using the endianess of the target
|
|
CPU.
|
|
|
|
@item xdef <symbol>[,<symbol>...]
|
|
See @code{global}.
|
|
|
|
@item xlib <symbol>[,<symbol>...]
|
|
See @code{global}.
|
|
|
|
@item xref <symbol>[,<symbol>...]
|
|
See @code{global}.
|
|
|
|
@item zmb <exp>[,<fill>]
|
|
Equivalent to @code{blk <exp>[,<fill>]}.
|
|
@end table
|
|
|
|
|
|
@section Structures
|
|
The oldstyle syntax is able to manage structures.
|
|
Structures can be defined in two ways:
|
|
@example
|
|
mylabel struct[ure]
|
|
<fields>
|
|
endstruct[ure]
|
|
@end example
|
|
or:
|
|
@example
|
|
struct[ure] mylabel
|
|
<fields>
|
|
endstruct[ure]
|
|
@end example
|
|
|
|
Any directive is allowed to define the structure fields. Labels can be used
|
|
to define offsets into the structure. The initialized data is used as default
|
|
value, whenever no value is given for a field when the structure is referenced.
|
|
|
|
Some examples of structure declarations:
|
|
@example
|
|
struct point
|
|
x db 4
|
|
y db 5
|
|
z db 6
|
|
endstruct
|
|
@end example
|
|
|
|
This will create the following labels:
|
|
@example
|
|
point.x ; 0 offsets
|
|
point.y ; 1
|
|
point.z ; 2
|
|
point ; 3 size of the structure
|
|
@end example
|
|
|
|
The structure can be used by optionaly redefining the fields value:
|
|
@example
|
|
point1 point
|
|
point2 point 1, 2, 3
|
|
point3 point ,,4
|
|
@end example
|
|
is equivalent to
|
|
@example
|
|
point1
|
|
db 4
|
|
db 5
|
|
db 6
|
|
point2
|
|
db 1
|
|
db 2
|
|
db 3
|
|
point3
|
|
db 4
|
|
db 5
|
|
db 4
|
|
@end example
|
|
|
|
|
|
@section Known Problems
|
|
|
|
Some known problems of this module at the moment:
|
|
|
|
@itemize @minus
|
|
|
|
@item Addresses assigned to @code{org} or to the current pc symbol @code{'*'}
|
|
(on the z80 the pc symbol is @code{'$'}) must be constant.
|
|
|
|
@item Expressions in an @code{if} directive must be constant.
|
|
|
|
@end itemize
|
|
|
|
@section Error Messages
|
|
|
|
This module has the following error messages:
|
|
|
|
@itemize @minus
|
|
@item 1001: syntax error
|
|
@item 1002: invalid extension
|
|
@item 1003: no space before operands
|
|
@item 1004: too many closing parentheses
|
|
@item 1005: missing closing parentheses
|
|
@item 1006: missing operand
|
|
@item 1007: garbage at end of line
|
|
@item 1008: %c expected
|
|
@item 1009: invalid data operand
|
|
@item 1010: , expected
|
|
@item 1011: identifier expected
|
|
@item 1012: illegal escape sequence %c
|
|
@item 1013: unexpected "%s" without "%s"
|
|
@item 1021: cannot open binary file "%s"
|
|
@item 1023: alignment too big
|
|
@item 1024: label <%s> has already been defined
|
|
@item 1025: skipping instruction in struct init
|
|
@item 1026: last %d bytes of string constant have been cut
|
|
|
|
@end itemize
|