Retro68/binutils/gas/doc/c-lm32.texi

@c Copyright (C) 2008-2017 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 LM32 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
* LM32-Chars::                Special Characters
@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-Chars
@subsection Special Characters

@cindex line comment character, LM32
@cindex LM32 line comment character
The presence of a @samp{#} on a line indicates the start of a comment
that extends to the end of the current line.  Note that if a line
starts with a @samp{#} character then it can also be a logical line
number directive (@pxref{Comments}) or a preprocessor
control command (@pxref{Preprocessing}).

@cindex line separator, LM32
@cindex statement separator, LM32
@cindex LM32 line separator
A semicolon (@samp{;}) can be used to separate multiple statements on
the same line.

@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.