376 lines
13 KiB
Text
376 lines
13 KiB
Text
@c Copyright (C) 2011-2022 Free Software Foundation, Inc.
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@c This is part of the GAS manual.
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@c For copying conditions, see the file as.texinfo.
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@ifset GENERIC
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@page
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@node Z80-Dependent
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@chapter Z80 Dependent Features
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@end ifset
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@ifclear GENERIC
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@node Machine Dependencies
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@chapter Z80 Dependent Features
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@end ifclear
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@cindex Z80 support
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@menu
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* Z80 Options:: Options
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* Z80 Syntax:: Syntax
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* Z80 Floating Point:: Floating Point
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* Z80 Directives:: Z80 Machine Directives
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* Z80 Opcodes:: Opcodes
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@end menu
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@node Z80 Options
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@section Command-line Options
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@cindex Z80 options
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@cindex options for Z80
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@c man begin OPTIONS
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@table @gcctabopt
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@cindex @code{-march=} command-line option, Z80
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@item -march=@var{CPU}[-@var{EXT}@dots{}][+@var{EXT}@dots{}]
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This option specifies the target processor. The assembler will issue
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an error message if an attempt is made to assemble an instruction which
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will not execute on the target processor. The following processor names
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are recognized:
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@code{z80},
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@code{z180},
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@code{ez80},
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@code{gbz80},
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@code{z80n},
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@code{r800}.
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In addition to the basic instruction set, the assembler can be told to
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accept some extention mnemonics. For example,
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@code{-march=z180+sli+infc} extends @var{z180} with @var{SLI} instructions and
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@var{IN F,(C)}. The following extentions are currently supported:
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@code{full} (all known instructions),
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@code{adl} (ADL CPU mode by default, eZ80 only),
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@code{sli} (instruction known as @var{SLI}, @var{SLL} or @var{SL1}),
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@code{xyhl} (instructions with halves of index registers: @var{IXL}, @var{IXH},
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@var{IYL}, @var{IYH}),
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@code{xdcb} (instructions like @var{RotOp (II+d),R} and @var{BitOp n,(II+d),R}),
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@code{infc} (instruction @var{IN F,(C)} or @var{IN (C)}),
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@code{outc0} (instruction @var{OUT (C),0}).
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Note that rather than extending a basic instruction set, the extention
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mnemonics starting with @code{-} revoke the respective functionality:
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@code{-march=z80-full+xyhl} first removes all default extentions and adds
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support for index registers halves only.
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If this option is not specified then @code{-march=z80+xyhl+infc} is assumed.
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@cindex @code{-local-prefix} command-line option, Z80
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@item -local-prefix=@var{prefix}
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Mark all labels with specified prefix as local. But such label can be
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marked global explicitly in the code. This option do not change default
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local label prefix @code{.L}, it is just adds new one.
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@cindex @code{-colonless} command-line option, Z80
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@item -colonless
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Accept colonless labels. All symbols at line begin are treated as labels.
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@cindex @code{-sdcc} command-line option, Z80
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@item -sdcc
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Accept assembler code produced by SDCC.
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@cindex @code{-fp-s} command-line option, Z80
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@item -fp-s=@var{FORMAT}
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Single precision floating point numbers format. Default: ieee754 (32 bit).
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@cindex @code{-fp-d} command-line option, Z80
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@item -fp-d=@var{FORMAT}
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Double precision floating point numbers format. Default: ieee754 (64 bit).
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@end table
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@c man end
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Floating point numbers formats.
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@table @option
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@item @code{ieee754}
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Single or double precision IEEE754 compatible format.
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@item @code{half}
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Half precision IEEE754 compatible format (16 bits).
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@item @code{single}
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Single precision IEEE754 compatible format (32 bits).
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@item @code{double}
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Double precision IEEE754 compatible format (64 bits).
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@item @code{zeda32}
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32 bit floating point format from z80float library by Zeda.
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@item @code{math48}
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48 bit floating point format from Math48 package by Anders Hejlsberg.
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@end table
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@cindex Z80 Syntax
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@node Z80 Syntax
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@section Syntax
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The assembler syntax closely follows the 'Z80 family CPU User Manual' by
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Zilog.
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In expressions a single @samp{=} may be used as ``is equal to''
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comparison operator.
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Suffices can be used to indicate the radix of integer constants;
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@samp{H} or @samp{h} for hexadecimal, @samp{D} or @samp{d} for decimal,
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@samp{Q}, @samp{O}, @samp{q} or @samp{o} for octal, and @samp{B} for
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binary.
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The suffix @samp{b} denotes a backreference to local label.
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@menu
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* Z80-Chars:: Special Characters
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* Z80-Regs:: Register Names
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* Z80-Case:: Case Sensitivity
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* Z80-Labels:: Labels
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@end menu
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@node Z80-Chars
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@subsection Special Characters
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@cindex line comment character, Z80
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@cindex Z80 line comment character
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The semicolon @samp{;} is the line comment character;
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If a @samp{#} appears as the first character of a line then the whole
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line is treated as a comment, but in this case the line could also be
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a logical line number directive (@pxref{Comments}) or a preprocessor
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control command (@pxref{Preprocessing}).
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@cindex line separator, Z80
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@cindex statement separator, Z80
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@cindex Z80 line separator
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The Z80 assembler does not support a line separator character.
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@cindex location counter, Z80
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@cindex hexadecimal prefix, Z80
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@cindex Z80 $
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The dollar sign @samp{$} can be used as a prefix for hexadecimal numbers
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and as a symbol denoting the current location counter.
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@cindex character escapes, Z80
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@cindex Z80, \
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A backslash @samp{\} is an ordinary character for the Z80 assembler.
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@cindex character constant, Z80
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@cindex single quote, Z80
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@cindex Z80 '
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The single quote @samp{'} must be followed by a closing quote. If there
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is one character in between, it is a character constant, otherwise it is
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a string constant.
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@node Z80-Regs
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@subsection Register Names
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@cindex Z80 registers
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@cindex register names, Z80
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The registers are referred to with the letters assigned to them by
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Zilog. In addition @command{@value{AS}} recognizes @samp{ixl} and
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@samp{ixh} as the least and most significant octet in @samp{ix}, and
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similarly @samp{iyl} and @samp{iyh} as parts of @samp{iy}.
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@c The @samp{'} in @samp{ex af,af'} may be omitted.
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@node Z80-Case
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@subsection Case Sensitivity
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@cindex Z80, case sensitivity
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@cindex case sensitivity, Z80
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Upper and lower case are equivalent in register names, opcodes,
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condition codes and assembler directives.
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The case of letters is significant in labels and symbol names. The case
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is also important to distinguish the suffix @samp{b} for a backward reference
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to a local label from the suffix @samp{B} for a number in binary notation.
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@node Z80-Labels
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@subsection Labels
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@cindex labels, Z80
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@cindex Z80 labels
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Labels started by @code{.L} acts as local labels. You may specify custom local
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label prefix by @code{-local-prefix} command-line option.
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Dollar, forward and backward local labels are supported. By default, all labels
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are followed by colon.
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Legacy code with colonless labels can be built with @code{-colonless}
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command-line option specified. In this case all tokens at line begin are treated
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as labels.
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@node Z80 Floating Point
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@section Floating Point
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@cindex floating point, Z80
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@cindex Z80 floating point
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Floating-point numbers of following types are supported:
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@table @option
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@item @code{ieee754}
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Supported half, single and double precision IEEE754 compatible numbers.
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@item @code{zeda32}
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32 bit floating point numbers from z80float library by Zeda.
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@item @code{math48}
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48 bit floating point numbers from Math48 package by Anders Hejlsberg.
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@end table
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@node Z80 Directives
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@section Z80 Assembler Directives
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@cindex Z80-only directives
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@command{@value{AS}} for the Z80 supports some additional directives for
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compatibility with other assemblers.
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These are the additional directives in @code{@value{AS}} for the Z80:
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@table @code
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@item @code{.assume ADL = @var{expression}}
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@cindex @code{.assume} directive, Z80
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Set ADL status for eZ80. Non-zero value enable compilation in ADL mode else
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used Z80 mode. ADL and Z80 mode produces incompatible object code. Mixing
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both of them within one binary may lead problems with disassembler.
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@item @code{db @var{expression}|@var{string}[,@var{expression}|@var{string}...]}
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@cindex @code{db} directive, Z80
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@itemx @code{defb @var{expression}|@var{string}[,@var{expression}|@var{string}...]}
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@cindex @code{defb} directive, Z80
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@itemx @code{defm @var{string}[,@var{string}...]}
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@cindex @code{defm} directive, Z80
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For each @var{string} the characters are copied to the object file, for
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each other @var{expression} the value is stored in one byte.
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A warning is issued in case of an overflow.
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Backslash symbol in the strings is generic symbol, it cannot be used as
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escape character. @xref{Ascii,,@code{.ascii}}.
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@item @code{dw @var{expression}[,@var{expression}...]}
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@cindex @code{dw} directive, Z80
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@itemx @code{defw @var{expression}[,@var{expression}...]}
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@cindex @code{defw} directive, Z80
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For each @var{expression} the value is stored in two bytes, ignoring
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overflow.
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@item @code{d24 @var{expression}[,@var{expression}...]}
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@cindex @code{d24} directive, Z80
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@itemx @code{def24 @var{expression}[,@var{expression}...]}
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@cindex @code{def24} directive, Z80
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For each @var{expression} the value is stored in three bytes, ignoring
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overflow.
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@item @code{d32 @var{expression}[,@var{expression}...]}
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@cindex @code{d32} directive, Z80
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@itemx @code{def32 @var{expression}[,@var{expression}...]}
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@cindex @code{def32} directive, Z80
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For each @var{expression} the value is stored in four bytes, ignoring
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overflow.
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@item @code{ds @var{count}[, @var{value}]}
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@cindex @code{ds} directive, Z80
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@itemx @code{defs @var{count}[, @var{value}]}
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@cindex @code{defs} directive, Z80
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@c Synonyms for @code{ds.b},
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@c which should have been described elsewhere
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Fill @var{count} bytes in the object file with @var{value}, if
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@var{value} is omitted it defaults to zero.
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@item @code{@var{symbol} defl @var{expression}}
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@cindex @code{defl} directive, Z80
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The @code{defl} directive is like @code{.set} but with different
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syntax. @xref{Set,,@code{.set}}.
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It set the value of @var{symbol} to @var{expression}. Symbols defined
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with @code{defl} are not protected from redefinition.
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@item @code{@var{symbol} equ @var{expression}}
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@cindex @code{equ} directive, Z80
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The @code{equ} directive is like @code{.equiv} but with different
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syntax. @xref{Equiv, ,@code{.equiv}}.
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It set the value of @var{symbol} to @var{expression}. It is an error
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if @var{symbol} is already defined. Symbols defined with @code{equ}
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are not protected from redefinition.
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@item @code{psect @var{name}}
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@cindex @code{psect} directive, Z80
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A synonym for @code{.section}, no second argument should be given.
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@xref{Section,,@code{.section}}.
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@item @code{xdef @var{symbol}}
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@cindex @code{xdef} directive, Z80
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A synonym for @code{.global}, make @var{symbol} is visible to linker.
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@xref{Global,,@code{.global}}.
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@item @code{xref @var{name}}
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@cindex @code{xref} directive, Z80
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A synonym for @code{.extern} (@ref{Extern,,@code{.extern}}).
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@ignore
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The following attributes will possibly be recognized in the future
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@table @code
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@item abs
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The section is to be absolute. @code{@value{AS}} will issue an error
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message because it can not produce an absolute section.
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@item global
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The section is to be concatenated with other sections of the same name
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by the linker, this is the default.
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@item local
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The section is not global. @code{@value{AS}} will issue a warning if
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object file format is not soff.
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@item ovrld
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The section is to be overlapped with other sections of the same name by
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the linker. @code{@value{AS}} will issue an error message
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because it can not mark a section as such.
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@item pure
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The section is marked as read only.
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@end table
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@end ignore
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@end table
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@node Z80 Opcodes
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@section Opcodes
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In line with common practice, Z80 mnemonics are used for the Z80,
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Z80N, Z180, eZ80, Ascii R800 and the GameBoy Z80.
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In many instructions it is possible to use one of the half index
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registers (@samp{ixl},@samp{ixh},@samp{iyl},@samp{iyh}) in stead of an
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8-bit general purpose register. This yields instructions that are
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documented on the eZ80 and the R800, undocumented on the Z80 and
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unsupported on the Z180.
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Similarly @code{in f,(c)} is documented on the R800, undocumented on
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the Z80 and unsupported on the Z180 and the eZ80.
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The assembler also supports the following undocumented Z80-instructions,
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that have not been adopted in any other instruction set:
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@table @code
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@item out (c),0
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Sends zero to the port pointed to by register @code{C}.
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@item sli @var{m}
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Equivalent to @code{@var{m} = (@var{m}<<1)+1}, the operand @var{m} can
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be any operand that is valid for @samp{sla}. One can use @samp{sll} as a
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synonym for @samp{sli}.
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@item @var{op} (ix+@var{d}), @var{r}
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This is equivalent to
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@example
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ld @var{r}, (ix+@var{d})
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@var{op} @var{r}
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ld (ix+@var{d}), @var{r}
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@end example
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The operation @samp{@var{op}} may be any of @samp{res @var{b},},
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@samp{set @var{b},}, @samp{rl}, @samp{rlc}, @samp{rr}, @samp{rrc},
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@samp{sla}, @samp{sli}, @samp{sra} and @samp{srl}, and the register
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@samp{@var{r}} may be any of @samp{a}, @samp{b}, @samp{c}, @samp{d},
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@samp{e}, @samp{h} and @samp{l}.
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@item @var{op} (iy+@var{d}), @var{r}
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As above, but with @samp{iy} instead of @samp{ix}.
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@end table
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The web site at @uref{http://www.z80.info} is a good starting place to
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find more information on programming the Z80.
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You may enable or disable any of these instructions for any target CPU
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even this instruction is not supported by any real CPU of this type.
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Useful for custom CPU cores.
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