Subversion Repositories openrisc_2011-10-31

@c Copyright 2008

@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 LM32-Dependent

@chapter LM32 Dependent Features

@end ifset

@ifclear GENERIC

@node Machine Dependencies

@chapter LM£" Dependent Features

@end ifclear

@cindex LM32 support

@menu

* LM32 Options::              Options

* LM32 Syntax::               Syntax

* LM32 Opcodes::              Opcodes

@end menu

@node LM32 Options

@section Options

@cindex LM32 options (none)

@cindex options for LM32 (none)

@table @code

@cindex @code{-mmultiply-enabled} command line option, LM32

@item -mmultiply-enabled

Enable multiply instructions.

@cindex @code{-mdivide-enabled} command line option, LM32

@item -mdivide-enabled

Enable divide instructions.

@cindex @code{-mbarrel-shift-enabled} command line option, LM32

@item -mbarrel-shift-enabled

Enable barrel-shift instructions.

@cindex @code{-msign-extend-enabled} command line option, LM32

@item -msign-extend-enabled

Enable sign extend instructions.

@cindex @code{-muser-enabled} command line option, LM32

@item -muser-enabled

Enable user defined instructions.

@cindex @code{-micache-enabled} command line option, LM32

@item -micache-enabled

Enable instruction cache related CSRs.

@cindex @code{-mdcache-enabled} command line option, LM32

@item -mdcache-enabled

Enable data cache related CSRs.

@cindex @code{-mbreak-enabled} command line option, LM32

@item -mbreak-enabled

Enable break instructions.

@cindex @code{-mall-enabled} command line option, LM32

@item -mall-enabled

Enable all instructions and CSRs.

@end table

@node LM32 Syntax

@section Syntax

@menu

* LM32-Regs::                 Register Names

* LM32-Modifiers::            Relocatable Expression Modifiers

@end menu

@node LM32-Regs

@subsection Register Names

@cindex LM32 register names

@cindex register names, LM32

LM32 has 32 x 32-bit general purpose registers @samp{r0},

@samp{r1}, ... @samp{r31}.

The following aliases are defined: @samp{gp} - @samp{r26},

@samp{fp} - @samp{r27}, @samp{sp} - @samp{r28},

@samp{ra} - @samp{r29}, @samp{ea} - @samp{r30},

@samp{ba} - @samp{r31}.

LM32 has the following Control and Status Registers (CSRs).

@table @code

@item IE

Interrupt enable.

@item IM

Interrupt mask.

@item IP

Interrupt pending.

@item ICC

Instruction cache control.

@item DCC

Data cache control.

@item CC

Cycle counter.

@item CFG

Configuration.

@item EBA

Exception base address.

@item DC

Debug control.

@item DEBA

Debug exception base address.

@item JTX

JTAG transmit.

@item JRX

JTAG receive.

@item BP0

Breakpoint 0.

@item BP1

Breakpoint 1.

@item BP2

Breakpoint 2.

@item BP3

Breakpoint 3.

@item WP0

Watchpoint 0.

@item WP1

Watchpoint 1.

@item WP2

Watchpoint 2.

@item WP3

Watchpoint 3.

@end table

@node LM32-Modifiers

@subsection Relocatable Expression Modifiers

@cindex LM32 modifiers

@cindex syntax, LM32

The assembler supports several modifiers when using relocatable addresses

in LM32 instruction operands.  The general syntax is the following:

@smallexample

modifier(relocatable-expression)

@end smallexample

@table @code

@cindex symbol modifiers

@item lo

This modifier allows you to use bits 0 through 15 of

an address expression as 16 bit relocatable expression.

@item hi

This modifier allows you to use bits 16 through 23 of an address expression

as 16 bit relocatable expression.

For example

@smallexample

ori  r4, r4, lo(sym+10)

orhi r4, r4, hi(sym+10)

@end smallexample

@item gp

This modified creates a 16-bit relocatable expression that is

the offset of the symbol from the global pointer.

@smallexample

mva r4, gp(sym)

@end smallexample

@item got

This modifier places a symbol in the GOT and creates a 16-bit

relocatable expression that is the offset into the GOT of this

symbol.

@smallexample

lw r4, (gp+got(sym))

@end smallexample

@item gotofflo16

This modifier allows you to use the bits 0 through 15 of an

address which is an offset from the GOT.

@item gotoffhi16

This modifier allows you to use the bits 16 through 31 of an

address which is an offset from the GOT.

@smallexample

orhi r4, r4, gotoffhi16(lsym)

addi r4, r4, gotofflo16(lsym)

@end smallexample

@end table

@node LM32 Opcodes

@section Opcodes

@cindex LM32 opcode summary

@cindex opcode summary, LM32

@cindex mnemonics, LM32

@cindex instruction summary, LM32

For detailed information on the LM32 machine instruction set, see

@url{http://www.latticesemi.com/products/intellectualproperty/ipcores/mico32/}.

@code{@value{AS}} implements all the standard LM32 opcodes.