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@c Copyright 2008, 2009, 2011

@c Free Software Foundation, Inc.

@c This is part of the GAS manual.

@c For copying conditions, see the file as.texinfo.

@ifset GENERIC

@page

@node RX-Dependent

@chapter RX Dependent Features

@end ifset

@ifclear GENERIC

@node Machine Dependencies

@chapter RX Dependent Features

@end ifclear

@cindex RX support

@menu

* RX-Opts::                   RX Assembler Command Line Options

* RX-Modifiers::              Symbolic Operand Modifiers

* RX-Directives::             Assembler Directives

* RX-Float::                  Floating Point

* RX-Syntax::                 Syntax

@end menu

@node RX-Opts

@section RX Options

@cindex options, RX

@cindex RX options

The Renesas RX port of @code{@value{AS}} has a few target specfic

command line options:

@table @code

@cindex @samp{-m32bit-doubles}

@item -m32bit-doubles

This option controls the ABI and indicates to use a 32-bit float ABI.

It has no effect on the assembled instructions, but it does influence

the behaviour of the @samp{.double} pseudo-op.

This is the default.

@cindex @samp{-m64bit-doubles}

@item -m64bit-doubles

This option controls the ABI and indicates to use a 64-bit float ABI.

It has no effect on the assembled instructions, but it does influence

the behaviour of the @samp{.double} pseudo-op.

@cindex @samp{-mbig-endian}

@item -mbig-endian

This option controls the ABI and indicates to use a big-endian data

ABI.  It has no effect on the assembled instructions, but it does

influence the behaviour of the @samp{.short}, @samp{.hword}, @samp{.int},

@samp{.word}, @samp{.long}, @samp{.quad} and @samp{.octa} pseudo-ops.

@cindex @samp{-mlittle-endian}

@item -mlittle-endian

This option controls the ABI and indicates to use a little-endian data

ABI.  It has no effect on the assembled instructions, but it does

influence the behaviour of the @samp{.short}, @samp{.hword}, @samp{.int},

@samp{.word}, @samp{.long}, @samp{.quad} and @samp{.octa} pseudo-ops.

This is the default.

@cindex @samp{-muse-conventional-section-names}

@item -muse-conventional-section-names

This option controls the default names given to the code (.text),

initialised data (.data) and uninitialised data sections (.bss).

@cindex @samp{-muse-renesas-section-names}

@item -muse-renesas-section-names

This option controls the default names given to the code (.P),

initialised data (.D_1) and uninitialised data sections (.B_1).

This is the default.

@cindex @samp{-msmall-data-limit}

@item -msmall-data-limit

This option tells the assembler that the small data limit feature of

the RX port of GCC is being used.  This results in the assembler

generating an undefined reference to a symbol called @code{__gp} for

use by the relocations that are needed to support the small data limit

feature.   This option is not enabled by default as it would otherwise

pollute the symbol table.

@cindex @samp{-mpid}

@item -mpid

This option tells the assembler that the position independent data of the

RX port of GCC is being used.  This results in the assembler

generating an undefined reference to a symbol called @code{__pid_base},

and also setting the RX_PID flag bit in the e_flags field of the ELF

header of the object file.

@cindex @samp{-mint-register}

@item -mint-register=@var{num}

This option tells the assembler how many registers have been reserved

for use by interrupt handlers.  This is needed in order to compute the

correct values for the @code{%gpreg} and @code{%pidreg} meta registers.

@end table

@node RX-Modifiers

@section Symbolic Operand Modifiers

@cindex RX modifiers

@cindex syntax, RX

@cindex %gp

The assembler supports one modifier when using symbol addresses

in RX instruction operands.  The general syntax is the following:

@smallexample

%gp(symbol)

@end smallexample

The modifier returns the offset from the @var{__gp} symbol to the

specified symbol as a 16-bit value.  The intent is that this offset

should be used in a register+offset move instruction when generating

references to small data.  Ie, like this:

@smallexample

  mov.W  %gp(_foo)[%gpreg], r1

@end smallexample

The assembler also supports two meta register names which can be used

to refer to registers whose values may not be known to the

programmer.  These meta register names are:

@table @code

@cindex @samp{%gpreg}

@item %gpreg

The small data address register.

@cindex @samp{%pidreg}

@item %pidreg

The PID base address register.

@end table

Both registers normally have the value r13, but this can change if

some registers have been reserved for use by interrupt handlers or if

both the small data limit and position independent data features are

being used at the same time.

@node RX-Directives

@section Assembler Directives

@cindex assembler directives, RX

@cindex RX assembler directives

The RX version of @code{@value{AS}} has the following specific

assembler directives:

@table @code

@item .3byte

@cindex assembler directive .3byte, RX

@cindex RX assembler directive .3byte

Inserts a 3-byte value into the output file at the current location.

@end table

@node RX-Float

@section Floating Point

@cindex floating point, RX

@cindex RX floating point

The floating point formats generated by directives are these.

@table @code

@cindex @code{float} directive, RX

@item .float

@code{Single} precision (32-bit) floating point constants.

@cindex @code{double} directive, RX

@item .double

If the @option{-m64bit-doubles} command line option has been specified

then then @code{double} directive generates @code{double} precision

(64-bit) floating point constants, otherwise it generates

@code{single} precision (32-bit) floating point constants.  To force

the generation of 64-bit floating point constants used the @code{dc.d}

directive instead.

@end table

@node RX-Syntax

@section Syntax for the RX

@menu

* RX-Chars::                Special Characters

@end menu

@node RX-Chars

@subsection Special Characters

@cindex line comment character, RX

@cindex RX line comment character

The presence of a @samp{;} appearing anywhere on a line indicates the

start of a comment that extends to the end of that line.

If a @samp{#} appears as the first character of a line then the whole

line is treated as a comment, but in this case the line can also be a

logical line number directive (@pxref{Comments}) or a preprocessor

control command (@pxref{Preprocessing}).

@cindex line separator, RX

@cindex statement separator, RX

@cindex RX line separator

The @samp{!} character can be used to separate statements on the same

line.