262 lines
8.3 KiB
Groff
262 lines
8.3 KiB
Groff
.\" $Header$
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.TH UNI_ASS 6ACK
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.ad
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.SH NAME
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uni_ass \- universal assembler, assembler\-loader
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.SH SYNOPSIS
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~em/lib/\fImach\fP/as [options] argument ...
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.SH DESCRIPTION
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The universal assembler is a framework allowing easy
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generation of an assembler for any byte oriented machine.
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The framework includes common pseudo instructions for name
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definition, label usage, storage allocation and initialization
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and expression evaluation.
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The resulting program assembles assembly modules.
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For some machines, it also does the link-editing (loading).
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Arguments may be flags, assembly language modules, or,
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in the case of an assembler\-loader,
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.IR arch (1)
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libraries.
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.br
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Flags are:
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.IP \-d\fIonum\fP
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This option controls the listing. Default is no listing.
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.I Onum
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is interpreted as an octal number.
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Each bit controls part of the listing as follows:
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.RS
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.nf
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0001: addresses in pass 1
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0002: generated code in pass 1
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0004: not used
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0010: addresses in pass 2
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0020: generated code in pass 2
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0040: source lines in pass 2
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0100: addresses in pass 3
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0200: generated code in pass 3
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0400: source lines in pass 3
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1000: force .list and ignore .nolist
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.fi
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.RE
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Thus bits in 0 to 8 control the listing format and
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bit 9 forces a complete listing.
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If
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.I onum
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is omitted or is 000 it is interpreted as 0700.
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If
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.I onum
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is 1000 it is interpreted as 1700.
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.br
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Note that '-d' alone (unless it contains bit 9)
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is not enough to get a listing.
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A .list pseudo is also needed in each module to be listed.
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Assemblers may be compiled with the listing facilities disabled.
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.IP -s[\fIonum\fP]
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This option controls the
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amount of symbolic debug information generated.
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.I Onum
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is interpreted as an octal number.
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The bits have the following meaning:
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.RS
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.nf
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001: external symbols
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002: local symbols
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004: local, compiler generated labels
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010: symbols defined in
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.I .symb
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pseudo instruction
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020: records for
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.I .line
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and
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.I .file
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statements
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040: section names
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.fi
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.RE
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Default is 073: all except local compiler labels.
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.IP -r
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Generate relocation information, for assemblers\-loaders that can.
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Assemblers always produce relocation information.
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.IP -b
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Turn off branch optimization.
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.IP -o\fIname\fP
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.IP -"o \fIname\fP"
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.I name
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is taken as the name of the
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resulting load file.
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The default name is \fBa.out\fP.
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.PP
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The assembler\-loaders assemble
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and link together assembly language modules
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machine
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from files and libraries,
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producing an \fIack.out\fP(5) format file, without relocation information.
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The assemblers produce a relocatable \fIack.out\fP(5) format file.
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.PP
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Two different types of arguments are allowed:
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.IP "1-"
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Assembly language modules
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.PD 0
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.IP "2-"
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UNIX archives, as maintained by arch(1). These archives must
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only contain
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assembly language modules with \fI.define\fP as their first
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statement.
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These are only accepted by assembler\-loaders.
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.PD
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.PP
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Note that assembler\-loaders cannot do a partial load;
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loading starts from assembly language and produces binary
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machine code. No relocation bits are produced.
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On the other hand, assemblers produce a relocatable file, to be handled
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by \fIled\fP(1).
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.SH "SECTIONS and TYPES"
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The statements allocating and initializing space,
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like instructions and
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some pseudo-instruction reserve that space in the current
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section.
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The currently reigning type of section is determined by
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the pseudo-instruction \fI.sect\fP.
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Actually, the assembler knows nothing about section types. Sections have
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numbers. The first section met gets number 0, the second gets number 1, etc.
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Therefore, every assembly files should start with a line just mentioning the
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sections used in the right order, so that no confusion can arise for \fIled\fP(1).
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.SH SYNTAX
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.PP
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The syntax of expressions is identical to the C expression syntax,
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except that square brackets are used for grouping.
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Labels are followed by a colon, and are identifiers or
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numbers between 0 and 9.
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Numeric labels can be referenced using the label followed by 'b' of 'f'
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determining the direction of search, backwards or forwards.
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.IP letters
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Both upper and lower case may be used and are seen as
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different.
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The underscore '_' is considered to be a letter.
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.IP identifiers
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Identifiers are a sequence of letters and digits, starting with
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a letter or a period '.'.
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Identifiers can, only once, receive a value through assignment or a
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label definition.
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.IP strings
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Strings are enclosed in single "'" or double """ quotes.
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The use of \eddd where ddd is an octal number and \en, \er,
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\et, \eb and \ef is allowed and has the same meaning as in the
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C language.
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.IP numbers
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Numbers are a sequence of letters and digits, starting with a
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digit.
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No difference is made between small and capital letters.
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.br
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The base of the number is determined in the following way:
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.nf
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if the number starts with '0x' it is hexadecimal else
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if the number starts with '0' it is octal else
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it's decimal.
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.fi
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The range of numbers depends on the machine.
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A rule of the thumb is that the width of the machine's registers
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the same is as the number of bits allowed in numbers.
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.IP comment
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The character '!' denotes the start of comment, every character
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up to the next newline is skipped.
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Exclamation marks in strings are not recognized as the start of
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comment.
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.IP statements
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Statements are separated by newlines and ';' and can be
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preceded by label definitions.
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Label definitions have the form "\fIidentifier\fP:" or
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"\fIdigit\fP:".
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Statements can be: empty, an assignment, an instruction or a
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pseudo-instruction.
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.IP assignment
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An assignment has the form:
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.br
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\fIidentifier\fP = \fIexpression\fP
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.br
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The identifier receives the value and type of the expression.
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.IP instruction
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The syntax of an instruction depends on the type of the target
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machine.
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.IP pseudo-instruction
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.de Pu
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.sp 1
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.ti +5
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\&\\$1
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.sp 1
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..
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.Pu ".extern \fIidentifier [, identifier]*\fP"
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The identifiers mentioned in the list are exported and can be
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used in other modules.
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.Pu ".define \fIidentifier [, identifier]*\fP"
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Used for modules that are to be part of a libary.
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The .define pseudo's should be the first in such modules.
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When scanning a module in a library the assembler\-loader
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checks whether any of its unsatified external references is
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mentioned in a .define list. If so, it includes that module in
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the program.
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The identifiers mentioned in the list are exported and can be
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used in other modules.
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.Pu ".data1 \fIexpression [, expression]*\fP"
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Initialize a sequence of bytes.
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This is not followed by automatic alignment.
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.Pu ".data2 \fIexpression [, expression]*\fP"
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Initialize a sequence of shorts (2-byte values).
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This is not followed by automatic alignment.
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.Pu ".data4 \fIexpression [, expression]*\fP"
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Initialize a sequence of longs (4-byte values).
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This is not followed by automatic alignment.
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.Pu ".ascii \fIstring\fP"
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Initialize a sequence of bytes with the value of the bytes in
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the string.
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This is not followed by automatic alignment.
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.Pu ".asciz \fIstring\fP"
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Initialize a sequence of bytes with the value of the bytes in
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the string and terminate this with an extra zero byte.
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This is not followed by automatic alignment.
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.Pu ".align [\fIexpression\fP]"
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Adjust the current position to a multiple of the value of the
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expression.
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The default is the word-size of the target machine.
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.Pu ".space \fIexpression\fP"
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Allocate the indicated amount of bytes.
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The expression must be absolute.
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.Pu ".comm \fIname\fP,\fIexpression\fP"
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Allocate the indicated amount of bytes and assign the location of the first
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byte allocated to
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.IR name ,
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unless
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.I name
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is defined elsewhere.
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If the scope of
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.I name
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is extern, then assemblers leave definition of
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.I name
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to the linkeditor \fIled\fP(1).
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.Pu .sect \fIname\fP
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section name definition.
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.Pu ".base \fIexpresssion\fP"
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Set the starting address of the first of the consecutive segments
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(text) to the value of the expression.
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The expression must be absolute.
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.Pu .assert \fIexpression\fP
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assembly-time assertion checking. Stop with a fatal error message when
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the value of the expression is zero.
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.Pu .symb, .line, .file
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symbolic debug
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.Pu .nolist, .list
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.br
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listing control
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.SH "SEE ALSO"
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ack(1), arch(1), ack.out(5)
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.SH DIAGNOSTICS
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Various diagnostics may be produced.
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The most likely errors, however, are unresolved references,
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probably caused by the omission of a library argument.
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.SH BUGS
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The alignment might give rise to internal assertion errors when
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the alignment requestes is larger than the machine dependent
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segment alignment.
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.br
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Identifiers declared as externals cannot be used as locals in
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any following module. This only is a problem for assembler\-loaders.
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