Subversion Repositories openrisc_2011-10-31

@c Copyright 2005

@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 M32C-Dependent

@chapter M32C Dependent Features

@end ifset

@ifclear GENERIC

@node Machine Dependencies

@chapter M32C Dependent Features

@end ifclear

@cindex M32C support

@code{@value{AS}} can assemble code for several different members of

the Renesas M32C family.  Normally the default is to assemble code for

the M16C microprocessor.  The @code{-m32c} option may be used to

change the default to the M32C microprocessor.

@menu

* M32C-Opts::                   M32C Options

* M32C-Modifiers::              Symbolic Operand Modifiers

@end menu

@node M32C-Opts

@section M32C Options

@cindex options, M32C

@cindex M32C options

The Renesas M32C version of @code{@value{AS}} has two

machine-dependent options:

@table @code

@item -m32c

@cindex @samp{-m32c} option, M32C

@cindex architecture options, M32C

@cindex M32C architecture option

Assemble M32C instructions.

@item -m16c

@cindex @samp{-m16c} option, M16C

@cindex architecture options, M16C

@cindex M16C architecture option

Assemble M16C instructions (default).

@end table

@node M32C-Modifiers

@section Symbolic Operand Modifiers

@cindex M32C modifiers

@cindex syntax, M32C

The assembler supports several modifiers when using symbol addresses

in M32C instruction operands.  The general syntax is the following:

@smallexample

%modifier(symbol)

@end smallexample

@table @code

@cindex symbol modifiers

@item %dsp8

@itemx %dsp16

These modifiers override the assembler's assumptions about how big a

symbol's address is.  Normally, when it sees an operand like

@samp{sym[a0]} it assumes @samp{sym} may require the widest

displacement field (16 bits for @samp{-m16c}, 24 bits for

@samp{-m32c}).  These modifiers tell it to assume the address will fit

in an 8 or 16 bit (respectively) unsigned displacement.  Note that, of

course, if it doesn't actually fit you will get linker errors.  Example:

@smallexample

mov.w %dsp8(sym)[a0],r1

mov.b #0,%dsp8(sym)[a0]

@end smallexample

@item %hi8

This modifier allows you to load bits 16 through 23 of a 24 bit

address into an 8 bit register.  This is useful with, for example, the

M16C @samp{smovf} instruction, which expects a 20 bit address in

@samp{r1h} and @samp{a0}.  Example:

@smallexample

mov.b #%hi8(sym),r1h

mov.w #%lo16(sym),a0

smovf.b

@end smallexample

@item %lo16

Likewise, this modifier allows you to load bits 0 through 15 of a 24

bit address into a 16 bit register.

@item %hi16

This modifier allows you to load bits 16 through 31 of a 32 bit

address into a 16 bit register.  While the M32C family only has 24

bits of address space, it does support addresses in pairs of 16 bit

registers (like @samp{a1a0} for the @samp{lde} instruction).  This

modifier is for loading the upper half in such cases.  Example:

@smallexample

mov.w #%hi16(sym),a1

mov.w #%lo16(sym),a0

@dots{}

lde.w [a1a0],r1

@end smallexample

@end table