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@c Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000, 2003, 2006

@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 M68HC11-Dependent

@chapter M68HC11 and M68HC12 Dependent Features

@end ifset

@ifclear GENERIC

@node Machine Dependencies

@chapter M68HC11 and M68HC12 Dependent Features

@end ifclear

@cindex M68HC11 and M68HC12 support

@menu

* M68HC11-Opts::                   M68HC11 and M68HC12 Options

* M68HC11-Syntax::                 Syntax

* M68HC11-Modifiers::              Symbolic Operand Modifiers

* M68HC11-Directives::             Assembler Directives

* M68HC11-Float::                  Floating Point

* M68HC11-opcodes::                Opcodes

@end menu

@node M68HC11-Opts

@section M68HC11 and M68HC12 Options

@cindex options, M68HC11

@cindex M68HC11 options

The Motorola 68HC11 and 68HC12 version of @code{@value{AS}} have a few machine

dependent options.

@table @code

@cindex @samp{-m68hc11}

@item -m68hc11

This option switches the assembler in the M68HC11 mode. In this mode,

the assembler only accepts 68HC11 operands and mnemonics. It produces

code for the 68HC11.

@cindex @samp{-m68hc12}

@item -m68hc12

This option switches the assembler in the M68HC12 mode. In this mode,

the assembler also accepts 68HC12 operands and mnemonics. It produces

code for the 68HC12. A few 68HC11 instructions are replaced by

some 68HC12 instructions as recommended by Motorola specifications.

@cindex @samp{-m68hcs12}

@item -m68hcs12

This option switches the assembler in the M68HCS12 mode.  This mode is

similar to @samp{-m68hc12} but specifies to assemble for the 68HCS12

series.  The only difference is on the assembling of the @samp{movb}

and @samp{movw} instruction when a PC-relative operand is used.

@cindex @samp{-mshort}

@item -mshort

This option controls the ABI and indicates to use a 16-bit integer ABI.

It has no effect on the assembled instructions.

This is the default.

@cindex @samp{-mlong}

@item -mlong

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

@cindex @samp{-mshort-double}

@item -mshort-double

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

This is the default.

@cindex @samp{-mlong-double}

@item -mlong-double

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

@cindex @samp{--strict-direct-mode}

@item --strict-direct-mode

You can use the @samp{--strict-direct-mode} option to disable

the automatic translation of direct page mode addressing into

extended mode when the instruction does not support direct mode.

For example, the @samp{clr} instruction does not support direct page

mode addressing. When it is used with the direct page mode,

@code{@value{AS}} will ignore it and generate an absolute addressing.

This option prevents @code{@value{AS}} from doing this, and the wrong

usage of the direct page mode will raise an error.

@cindex @samp{--short-branches}

@item --short-branches

The @samp{--short-branches} option turns off the translation of

relative branches into absolute branches when the branch offset is

out of range. By default @code{@value{AS}} transforms the relative

branch (@samp{bsr}, @samp{bgt}, @samp{bge}, @samp{beq}, @samp{bne},

@samp{ble}, @samp{blt}, @samp{bhi}, @samp{bcc}, @samp{bls},

@samp{bcs}, @samp{bmi}, @samp{bvs}, @samp{bvs}, @samp{bra}) into

an absolute branch when the offset is out of the -128 .. 127 range.

In that case, the @samp{bsr} instruction is translated into a

@samp{jsr}, the @samp{bra} instruction is translated into a

@samp{jmp} and the conditional branches instructions are inverted and

followed by a @samp{jmp}. This option disables these translations

and @code{@value{AS}} will generate an error if a relative branch

is out of range. This option does not affect the optimization

associated to the @samp{jbra}, @samp{jbsr} and @samp{jbXX} pseudo opcodes.

@cindex @samp{--force-long-branches}

@item --force-long-branches

The @samp{--force-long-branches} option forces the translation of

relative branches into absolute branches. This option does not affect

the optimization associated to the @samp{jbra}, @samp{jbsr} and

@samp{jbXX} pseudo opcodes.

@cindex @samp{--print-insn-syntax}

@item --print-insn-syntax

You can use the @samp{--print-insn-syntax} option to obtain the

syntax description of the instruction when an error is detected.

@cindex @samp{--print-opcodes}

@item --print-opcodes

The @samp{--print-opcodes} option prints the list of all the

instructions with their syntax. The first item of each line

represents the instruction name and the rest of the line indicates

the possible operands for that instruction. The list is printed

in alphabetical order. Once the list is printed @code{@value{AS}}

exits.

@cindex @samp{--generate-example}

@item --generate-example

The @samp{--generate-example} option is similar to @samp{--print-opcodes}

but it generates an example for each instruction instead.

@end table

@node M68HC11-Syntax

@section Syntax

@cindex M68HC11 syntax

@cindex syntax, M68HC11

In the M68HC11 syntax, the instruction name comes first and it may

be followed by one or several operands (up to three). Operands are

separated by comma (@samp{,}). In the normal mode,

@code{@value{AS}} will complain if too many operands are specified for

a given instruction. In the MRI mode (turned on with @samp{-M} option),

it will treat them as comments. Example:

@smallexample

inx

lda  #23

bset 2,x #4

brclr *bot #8 foo

@end smallexample

@cindex M68HC11 addressing modes

@cindex addressing modes, M68HC11

The following addressing modes are understood for 68HC11 and 68HC12:

@table @dfn

@item Immediate

@samp{#@var{number}}

@item Address Register

@samp{@var{number},X}, @samp{@var{number},Y}

The @var{number} may be omitted in which case 0 is assumed.

@item Direct Addressing mode

@samp{*@var{symbol}}, or @samp{*@var{digits}}

@item Absolute

@samp{@var{symbol}}, or @samp{@var{digits}}

@end table

The M68HC12 has other more complex addressing modes. All of them

are supported and they are represented below:

@table @dfn

@item Constant Offset Indexed Addressing Mode

@samp{@var{number},@var{reg}}

The @var{number} may be omitted in which case 0 is assumed.

The register can be either @samp{X}, @samp{Y}, @samp{SP} or

@samp{PC}.  The assembler will use the smaller post-byte definition

according to the constant value (5-bit constant offset, 9-bit constant

offset or 16-bit constant offset).  If the constant is not known by

the assembler it will use the 16-bit constant offset post-byte and the value

will be resolved at link time.

@item Offset Indexed Indirect

@samp{[@var{number},@var{reg}]}

The register can be either @samp{X}, @samp{Y}, @samp{SP} or @samp{PC}.

@item Auto Pre-Increment/Pre-Decrement/Post-Increment/Post-Decrement

@samp{@var{number},-@var{reg}}

@samp{@var{number},+@var{reg}}

@samp{@var{number},@var{reg}-}

@samp{@var{number},@var{reg}+}

The number must be in the range @samp{-8}..@samp{+8} and must not be 0.

The register can be either @samp{X}, @samp{Y}, @samp{SP} or @samp{PC}.

@item Accumulator Offset

@samp{@var{acc},@var{reg}}

The accumulator register can be either @samp{A}, @samp{B} or @samp{D}.

The register can be either @samp{X}, @samp{Y}, @samp{SP} or @samp{PC}.

@item Accumulator D offset indexed-indirect

@samp{[D,@var{reg}]}

The register can be either @samp{X}, @samp{Y}, @samp{SP} or @samp{PC}.

@end table

For example:

@smallexample

ldab 1024,sp

ldd [10,x]

orab 3,+x

stab -2,y-

ldx a,pc

sty [d,sp]

@end smallexample

@node M68HC11-Modifiers

@section Symbolic Operand Modifiers

@cindex M68HC11 modifiers

@cindex syntax, M68HC11

The assembler supports several modifiers when using symbol addresses

in 68HC11 and 68HC12 instruction operands.  The general syntax is

the following:

@smallexample

%modifier(symbol)

@end smallexample

@table @code

@cindex symbol modifiers

@item %addr

This modifier indicates to the assembler and linker to use

the 16-bit physical address corresponding to the symbol.  This is intended

to be used on memory window systems to map a symbol in the memory bank window.

If the symbol is in a memory expansion part, the physical address

corresponds to the symbol address within the memory bank window.

If the symbol is not in a memory expansion part, this is the symbol address

(using or not using the %addr modifier has no effect in that case).

@item %page

This modifier indicates to use the memory page number corresponding

to the symbol.  If the symbol is in a memory expansion part, its page

number is computed by the linker as a number used to map the page containing

the symbol in the memory bank window.  If the symbol is not in a memory

expansion part, the page number is 0.

@item %hi

This modifier indicates to use the 8-bit high part of the physical

address of the symbol.

@item %lo

This modifier indicates to use the 8-bit low part of the physical

address of the symbol.

@end table

For example a 68HC12 call to a function @samp{foo_example} stored in memory

expansion part could be written as follows:

@smallexample

call %addr(foo_example),%page(foo_example)

@end smallexample

and this is equivalent to

@smallexample

call foo_example

@end smallexample

And for 68HC11 it could be written as follows:

@smallexample

ldab #%page(foo_example)

stab _page_switch

jsr  %addr(foo_example)

@end smallexample

@node M68HC11-Directives

@section Assembler Directives

@cindex assembler directives, M68HC11

@cindex assembler directives, M68HC12

@cindex M68HC11 assembler directives

@cindex M68HC12 assembler directives

The 68HC11 and 68HC12 version of @code{@value{AS}} have the following

specific assembler directives:

@table @code

@item .relax

@cindex assembler directive .relax, M68HC11

@cindex M68HC11 assembler directive .relax

The relax directive is used by the @samp{GNU Compiler} to emit a specific

relocation to mark a group of instructions for linker relaxation.

The sequence of instructions within the group must be known to the linker

so that relaxation can be performed.

@item .mode [mshort|mlong|mshort-double|mlong-double]

@cindex assembler directive .mode, M68HC11

@cindex M68HC11 assembler directive .mode

This directive specifies the ABI.  It overrides the @samp{-mshort},

@samp{-mlong}, @samp{-mshort-double} and @samp{-mlong-double} options.

@item .far @var{symbol}

@cindex assembler directive .far, M68HC11

@cindex M68HC11 assembler directive .far

This directive marks the symbol as a @samp{far} symbol meaning that it

uses a @samp{call/rtc} calling convention as opposed to @samp{jsr/rts}.

During a final link, the linker will identify references to the @samp{far}

symbol and will verify the proper calling convention.

@item .interrupt @var{symbol}

@cindex assembler directive .interrupt, M68HC11

@cindex M68HC11 assembler directive .interrupt

This directive marks the symbol as an interrupt entry point.

This information is then used by the debugger to correctly unwind the

frame across interrupts.

@item .xrefb @var{symbol}

@cindex assembler directive .xrefb, M68HC11

@cindex M68HC11 assembler directive .xrefb

This directive is defined for compatibility with the

@samp{Specification for Motorola 8 and 16-Bit Assembly Language Input

Standard} and is ignored.

@end table

@node M68HC11-Float

@section Floating Point

@cindex floating point, M68HC11

@cindex M68HC11 floating point

Packed decimal (P) format floating literals are not supported.

Feel free to add the code!

The floating point formats generated by directives are these.

@table @code

@cindex @code{float} directive, M68HC11

@item .float

@code{Single} precision floating point constants.

@cindex @code{double} directive, M68HC11

@item .double

@code{Double} precision floating point constants.

@cindex @code{extend} directive M68HC11

@cindex @code{ldouble} directive M68HC11

@item .extend

@itemx .ldouble

@code{Extended} precision (@code{long double}) floating point constants.

@end table

@need 2000

@node M68HC11-opcodes

@section Opcodes

@cindex M68HC11 opcodes

@cindex opcodes, M68HC11

@cindex instruction set, M68HC11

@menu

* M68HC11-Branch::                 Branch Improvement

@end menu

@node M68HC11-Branch

@subsection Branch Improvement

@cindex pseudo-opcodes, M68HC11

@cindex M68HC11 pseudo-opcodes

@cindex branch improvement, M68HC11

@cindex M68HC11 branch improvement

Certain pseudo opcodes are permitted for branch instructions.

They expand to the shortest branch instruction that reach the

target. Generally these mnemonics are made by prepending @samp{j} to

the start of Motorola mnemonic. These pseudo opcodes are not affected

by the @samp{--short-branches} or @samp{--force-long-branches} options.

The following table summarizes the pseudo-operations.

@smallexample

                        Displacement Width

     +-------------------------------------------------------------+

     |                     Options                                 |

     |    --short-branches           --force-long-branches         |

     +--------------------------+----------------------------------+

  Op |BYTE             WORD     | BYTE          WORD               |

     +--------------------------+----------------------------------+

 bsr | bsr <pc-rel>    <error>  |               jsr <abs>          |

 bra | bra <pc-rel>    <error>  |               jmp <abs>          |

jbsr | bsr <pc-rel>   jsr <abs> | bsr <pc-rel>  jsr <abs>          |

jbra | bra <pc-rel>   jmp <abs> | bra <pc-rel>  jmp <abs>          |

 bXX | bXX <pc-rel>    <error>  |               bNX +3; jmp <abs>  |

jbXX | bXX <pc-rel>   bNX +3;   | bXX <pc-rel>  bNX +3; jmp <abs>  |

     |                jmp <abs> |                                  |

     +--------------------------+----------------------------------+

XX: condition

NX: negative of condition XX

@end smallexample

@table @code

@item jbsr

@itemx jbra

These are the simplest jump pseudo-operations; they always map to one

particular machine instruction, depending on the displacement to the

branch target.

@item jb@var{XX}

Here, @samp{jb@var{XX}} stands for an entire family of pseudo-operations,

where @var{XX} is a conditional branch or condition-code test.  The full

list of pseudo-ops in this family is:

@smallexample

 jbcc   jbeq   jbge   jbgt   jbhi   jbvs   jbpl  jblo

 jbcs   jbne   jblt   jble   jbls   jbvc   jbmi

@end smallexample

For the cases of non-PC relative displacements and long displacements,

@code{@value{AS}} issues a longer code fragment in terms of

@var{NX}, the opposite condition to @var{XX}.  For example, for the

non-PC relative case:

@smallexample

    jb@var{XX} foo

@end smallexample

gives

@smallexample

     b@var{NX}s oof

     jmp foo

 oof:

@end smallexample

@end table