05. Assembler

MPASM Assembler

with MPLINK and MPLIBLinker and LibrarianLinker and Librarian

MPASM Assembler :: Slide 1 of 69David Rye :: MTRX 3700

What is ?What is

A bl L

?

Assembly Language Instructions for a P written in the form of mnemonics Confusingly also referred to as assembler as in assembler Confusingly also referred to as assembler , as in assembler

code, or to program in assembler Assembler

A program that translates from an assembly language to machine instructionsA C A bl i th t t f A Cross Assembler is a program that runs on one type of processor (e.g. x86) and produces machine instructions for another type (PIC)

AssembleAssemble Translate to machine instructions (an assembly language is

assembled, a HLL is compiled or interpreted) Assembly

The process of translation


What is an Assembler?What is an Assembler At least: a translator from mnemonics to binary instructions

? At least: a translator from mnemonics to binary instructions

ADLW hAA 00001111 10101010I i bl bl Invariably, an assembler: Has a set of directives that control assembler processing Calculates relative addresses from instruction labels

Most assemblers are macro assemblers Perform macro substitution, expansion and calculation at assembly time

M l ll bl l i t hi h l l f Macro language allows assembly language programming at a higher level of abstractionlocal i = 0 ; establish local index variable and initializewhile i < 8 ; do 8 times

i += 1 ; increment loop counter

endw ; break after eight loops

Structured assembler see Peatman for example and source code Very simple form of compiler Allows control structures (e.g. if-then-else) that are active at run time


Simple Workflow AssemblerSimple Workflow - Assembler

With a single assembly language file that references only absolute addresses, workflow is straightforward

Assemble to absolute object file using MPASMj g Load to device we will use the MPLAB IDE


MPASM Assembler FilesMPASM Assembler Files

.ASM Assembly language source .HEX Absolute machine code, Intel Hex format

.LST Assembler listing file ERR Assembler error messages .ERR Assembler error messages .XRF Cross-reference listing file .MAP Load map file .COFF Debug symbol .O Relocatable object file


Assembler Listing File ( LST) FormatAssembler Listing File (.LST) FormatMPASM 03 20 07 Released MANUAL ASM 3-23-2003 18:33:38 PAGE 1MPASM 03.20.07 Released MANUAL.ASM 3-23-2003 18:33:38 PAGE 1

LOC OBJECT CODE LINE SOURCE TEXTVALUE

00001 ; Sample MPASM Source Code.00002 ;00002 ;00003 list p=18F452

0000000B 00004 Dest equ 0x0B000000 00005 org 0x0000

00006 000000 00007 Start:000000 0E0A 00008 movlw 0x0A000002 6E0B 00009 movwf Dest00000 6 0 00009 o est000004 EF00 F000 00010 goto Start

00011 0001FE 00012 org 0x01FE0001FE EF00 F000 00013 t St t0001FE EF00 F000 00013 goto Start

00014 00015 end


Assembler Listing File ( LST) FormatAssembler Listing File (.LST) FormatMPASM 03 20 07 Released MANUAL ASM 3-23-2003 18:33:38 PAGE 2MPASM 03.20.07 Released MANUAL.ASM 3-23-2003 18:33:38 PAGE 2SYMBOL TABLELABEL VALUE

Dest 0000000BStart 0000000018F452 00000001__18F452 00000001

MEMORY USAGE MAP ('X' = Used, '-' = Unused)0000 : XXXXXXXX-------- ---------------- ---------------- ----------------01C0 : ---------------- ---------------- ---------------- --------------XX0200 : XX-------------- ---------------- ---------------- ----------------All other memory blocks unused.ot e e o y b oc s u used.Program Memory Bytes Used: 12Program Memory Bytes Free: 32756Errors : 0Warnings : 0 reported, 0 suppressedMessages : 0 reported, 0 suppressed


g p pp

What is ?What is ?

Linker Program that translates one or more relocatable object

modules into executable instructions with absolute addressesaddresses

Lib Library Collection of relocatable object modules

Librarian Program that creates and manages a library Add, remove, replace, list object modules


Workflow Assembler and LinkerWorkflow Assembler and Linker

A bl bl l S Fil Assemble one or more assembly language Source Files xxxx.asm to Relocatable Object Files using MPASM

Link relocatable object files with linker MPLINK to Link relocatable object files with linker MPLINK to form absolute executable file

Even one file must be linked!e o e e ust be ed(to calculate absolute addresses)


Workflow LibrarianWorkflow Librarian

Librarian MPLIB can be used to form libraries of

l bl bj drelocatable object code. For example:

clib.lib p18f452.lib myLib.lib


The Assembler: MPASMThe Assembler: MPASM

Universal macro assembler for all PIC devices Device capabilities and mnemonics (of course)

h f d i t thchange from one device to another

Choice of three interfaces Command-line (DOS shell) interface Stand-alone MS-Windows application Integrated with Microchips MPLAB IDE

Free (part of MPLAB IDE) (p )


MPLAB Help FilesMPLAB Help Files

MPLAB is Microchips (free) IDE Available from UoS website

The on-line help files in MPLAB are very good Go to Help Topics MPASM Assembler Go to Help Topics MPASM Assembler


Assembler SyntaxAssembler Syntax

Rules for assembly language source codeRules for assembly language source code


Syntax: Assembly Language FileSyntax: Assembly Language File

Each line of code may contain zero or more Labels Mnemonics Operands Comments

Maximum line length is 255 characters Whitespace is not significantp g

Wait:btfss PIR1, ADIF ; wait for A/D conversion done



L b l Labels Must start in column 1 Are case-sensitive by defaulty Must begin with alphabetic character or underscore (_) Can be 32 characters long

C b f ll d b l ( ) hit Can be followed by a colon (:) or whitespace Mnemonics

Must not start in column 1Must not start in column 1 Must be separated from label(s) by colon (:) or whitespace

Operands Must be separated from mnemonics by whitespace Multiple operands must be separated by a comma (,)

Comments Comments Can start anywhere Everything from a semicolon (;) to the end-of-line is a comment



Radixes (Bases) Hexadecimal: HA3 or 0xA3 Decimal D163 Note all the same number, Octal: O243 but different radixes!

Bi 10100011 Binary: B10100011

D f lt di i H d i l Default radix is Hexadecimal There is no floating point type

ASCII Character: C or AC ASCII String: A String ASCII String: A String

Note! A string is not Null-terminated unless you add the terminator!


Assembler Control RadixAssembler Control Radix

RADIX: Specify Default Radix (Base)di d f lt diRadix

options are hex, dec, octif t ifi d di d f lt t if not specified, radix defaults to hex


Assembler DirectivesAssembler Directives

Directives =Directives Instructions in the source code that tell the

assembler how to assemble a source fileassembler how to assemble a source file


Assembler DirectivesAssembler Directives

Assembler directives are placed in the assembly language source file, and tell the assembler how to assemble the source.

They are not active at run time

There are five types of assembler directives, for: Assembler ControlAssembler Control Conditional Assembly Data DefinitionData Definition Macro Definition Object File Control


j

Assembler Control SymbolsAssembler Control Symbols

EQU: Defines a Symbolic Label for a ConstantHEIGHT equ D17 equ DEPTH equ HEIGHT * 2

q p

expr is a numberSee examples in P18452 INCSee examples in P18452.INC

Length set 2Area set HEIGHT * LengthLength set Length + 1

SET: Defines a Symbolic Label for a Variable set

g g Same as EQU except that value of can be redefined with another SET


Assembler Control SymbolsAssembler Control Symbols

CONSTANT: Declare Symbol Constantconstant BuffLen = D512constant = p

[, = ] A constant must be initialised when defined,

and cannot be changedand cannot be changed

variable RecLen = D64variable Memory = RecLen * BuffLen

VARIABLE: Declare Symbol Variablevariable [= ]

[, [= ]] y[, [ p ]] A variable does not need to be initialised when defined (as in SET), and value can be changed

b tlsubsequently Variable value must be formed before being usedas an operand


Assembler Control Placing CodeAssembler Control Placing Code

ORG: Set Absolute Program Originorg 0x000008 org ggoto HighISR

; HighISR replaced by address

g p Sets the value of the assemblers location counter The location counter value at assembly time

corresponds to the PC value at run time

HighISR:

corresponds to the PC value at run time

Cannot be used when generating a HighISR:; High priority ISR goes here

RETFIE

relocatable object file Use CODE, UDATA, IDATA directives instead

RETFIE


Assembler Control DefinesAssembler Control Defines

#DEFINE: Define a Text Substitution Symbol#UNDEFINE: Delete a Text Substitution Symbol

#define MAX_INT D65535

#define DEBUG#define []#undefine

S S C#ifdef DEBUG

constant BuffLen = 8

Same mechanism as in ANSI C will be substituted for from

the point where #definedvariable RecLen = 4

#elseconstant BuffLen = D512#IFDEF: Execute if Symbol is Defined

#IFNDEF: Execute if Symbol is Not Defined variable RecLen = D64#endif

#IFNDEF: Execute if Symbol is Not Defined#ENDIF: Terminates Conditional Block

ifdef #undefine DEBUG

endif


Assembler Control IncludeAssembler Control Include

INCLUDE: Literally include a file at this point#include

; get register symbols, etc#include P18F452 INC

p#include path\file#include path\file

S S C #include P18F452.INC

; get config bits#include config inc

Similar to ANSI C No difference in behaviour between the

forms and file and file #include config.inc Search path is current directory; source filedirectory; MPASM executable directory


Assembler Control Listing FileAssembler Control Listing File

TITLE: Specify Program Title for listingSUBTITLE: Specify Program Subtitle for listing

title subtitle

If d fi d d i t h title Code Release 2006-03-16; Stuff here

If defined, title and subtitle print on eachpage of the listing

pagesubtitle Memory Diagnostics; Memory Diagnostic code here

SPACE: Insert Blank LinesPAGE: Insert Page Eject

space ; Memory Diagnostic code here space page space inserts a number of blank lines p

into the listing file page inserts a new page character

into the listing file


g


LIST: Turn on listing, with optionsNOLIST: Turn off listing ; suppress listing of symbols etc; suppress listing of symbols, etc

nolist include P18F452.INClist

list [[, [, ...] ] ]

nolist listnolist list, with no options, turns listing on Options (13 of them) control various p ( )

listing settings see Data Sheet nolist turns off listing

EXPAND: Expand Macros in ListingNOEXPAND: Dont Expand Macros in Listing

expand or noexpand Expand or suppress expansion of all macros

in listing file


in listing file


MESSG: Create User-defined MessageERROR: Issue a User-defined Error Message if size > MAX_INT16 bit l d derror 16-bit value exceeded

endifmessg message_texterror error_text

B th i t d fi d Both print user-defined messages


Assembler Control ConfigurationAssembler Control Configuration

RADIX: Specify Default Radix (Base)Radix _ options are hex, dec, oct if not specified, radix defaults to hex

ERRORLEVEL: Set Diagnostic Message Levelerrorlevel 0|1|2|errorlevel 0|1|2| 0 is show all errors and warnings, 2 is show none Important hint!! Use errorlevel 0 - suppresses a single message


The low high and upper OperatorsThe low, high and upper Operators

LOW: Return the low byte (bits )of a multi-byte value

table:data Im ad t b tl HIGH: Return the high byte (bits )

of a multi-byte valueUPPER: Return the upper byte (bits )

data beatlesdata eater

l UPPER t blpp y ( )of a multi-byte value movlw UPPER tablemovwf TBLPTRU movlw HIGH table

fmovwf TBLPTRH movlw LOW table movwf TBLPTRL


The banksel DirectiveThe banksel Directive

BANKSEL: Generate bank selecting code (movlb) that selects the correct

banksel Var1 ;Select correct bank for Var1movwf Var1 ;Write to Var1

bank for a variable in any bank of RAMbanksel label


Assembler Control TerminationAssembler Control Termination

END: End of Assembly Language ProgramendEvery program must finish with an end directiveEverything after end is ignored


Conditional Assembly DirectivesConditional Assembly Directives

Permit sections of code to be conditionally assembled

Similar to C language e.g.g g g#ifdef#endif


Conditional Assembly If ElseConditional Assembly If-Else

Have already seen IFDEF, IFNDEF

IF: Begin Conditionally Assembled BlockELSE: Begin Alternative Block to IFENDIF: End Conditional Assembly BlockENDIF: End Conditional Assembly Block

#if

[#else ]

#endif#endif is evaluated non-zero is interpreted

as logically TRUE


Conditional Assembly WhileConditional Assembly While

WHILE: Loop While is TRUEENDW: End of a WHILE Loop

hil < >while

endw is evaluated non-zero value is

interpreted as logically TRUE cannot exceed 100 lines Can not loop more than 256 timesActive at assembly time


The Five ENDsThe Five ENDs

Dont confuse the various ENDx directives!!END: End of the Assembly Program any program endENDIF: End of a Conditional Block if endifENDW: End of a While Loop while endw

ENDM: End of a Macro Definition macro endmENDC: End an Automatic Constant Block cblock endc

(a cblock is used to define a list of named constants)(a cblock is used to define a list of named constants)


Data Definition DirectivesData Definition Directives

Control memory allocation and symbol definition This is how to define named variables


Data Definition IntegersData Definition - Integers

DB: Declare a Byte of DataDW: Declare a Word of Data ; Absolute code in FLASHorg 0x2000DE: Declare a Byte of EEPROM Data

org 0x2000errorFlags: db B10100011

highLimit: dw D350db [,,...,] dw [,, ,] highLimit: dw D 350

aString: db Hello Room!

dw [,,...,] de [,,...,]

all reserve storage in program or data memory andinitialize the memory location(s)

; Relocatable code in RAMudata 0x300

myVariable: db D99

db packs 8-bit values into 16-bit memory. dw behaves like db for PIC18 devices dw packs words into data memory in low-dw packs words into data memory in low

byte/high-byte orderSee the idata directived places 8 bit values into EEPROM


de places 8-bit values into EEPROM

Data Definition Strings TablesData Definition Strings, Tables

DA: Store Strings in Program Memory aString:da rubricda [,,...,]

aNullTerminatedString:da Null terminated, 0

p [, p , , p ] generates packed 14-bit numbers representing

7-bit ASCII characters

DT: Define Tabledt [,,...,]

squares:dt 0, 1, 4, 9, 16, 25, 36

p [, p , , p ]

dt generates a series of RETLW instructions, one for each which must be an 8-bitone for each , which must be an 8-bitvalue. When each is executed, returns with thevalue in WREG.


Data Definition GeneralData Definition General

DATA: Create Numeric and Text Datadata ,[,,...,]

data C ; one characterdata Sharp ; string

p ,[, p , , p ]data "

[,"",...] General data definition - places numeric or Numbers:

data 1, 2, 3 ; some numbers General data definition - places numeric or

text data into Program Memory Single characters placed in low byte of word

St i k d 2 h t 16 bit d fi t Strings packed 2 characters per 16-bit word, firstcharacter in LSB Can be used to declare values in IDATA

FILL: Fill memory block with valuefill 0x5555 D10fill count fill 0x5555, D10fill (goto 0), NEXT_BLOCK-$

fill , count If bracketed by parentheses, can be a

(16-bit long) assembly language instruction


Data Definition Un initialised MemoryData Definition Un-initialised Memory

RES: Reserve Memory; Absolute coderes org 0x2000

res 0x20 ; 32 bytes_

Reserve a number of bytesof memoryDo not initialize the memory

; Relocatable codeGlobals:

Do not initialize the memory In absolute code, Program Memory will be

reservedudata

temp res 1time res 2 ; 2 bytes

In relocatable code, memory can be either inin Program Memory or Data MemorySee code directive (Program Memory) andudata directive (Data Memory)


Data Definition C ConfigurationData Definition C Configuration

PROCESSOR: Set Processor Typeprocessor p p _ yp

CONFIG: Set Processor Configuration Bitsconfig =__config is deprecatedSets the configuration bits Processor must previously have been declared If done in the code, MPLAB IDE settingsIf done in the code, MPLAB IDE settings

are over-ridden see config.inc on server See usage, definitions in 18F452.INC

__IDLOCS: Set values of processor ID Locations Similar to CONFIG


__

Data Definition RAM ConfigurationData Definition RAM Configuration

_ _ MAXRAM: Specify maximum RAM address processor 18F452__MAXRAM H'FFFmaxram ; Unimplemented banks__BADRAM H'600'-H'F7F

__ p Specifies the highest address of physical RAM

; Unimplemented SFRs__BADRAM H'F85'-H'F88'

8 91

_ _BADRAM: Specify invalid RAM addresses__badram Can have more than one badram directive __BADRAM H'F8E'-H'F91'

__BADRAM H'F97'-H'F9C'__BADRAM H'FA3'-H'FA5'

Can have more than one __badram directive __maxram and __badram together allow strictRAM address checking

__BADRAM H'FAA'__BADRAM H'FB4'-H'FB9


Macro Definition DirectivesMacro Definition Directives

Control execution and data allocation within macros

Description of the macro language follows thisDescription of the macro language follows this section.


Macro DefinitionsMacro Definitions

MACRO: Declare a Macro DefinitionENDM: End a Macro Definition

len equ 10 ; globalsize equ 20

m_buffer:macro sizelocal len label

macro [,...,]

endm local len, labellen set size ; local lenlabel res lenl t l i

endm

LOCAL: Declare Local Macro Variable len set len - sizeendmlocal [,]

Declared inside a macro local scope

EXITM: Exit from a Macroexitm Forces immediate exit from macro

during assembly


Macro LanguageMacro Language

A simple form of preprocessor / compiler thatA simple form of preprocessor / compiler thatallows a limited higher-level abstraction


MacrosMacros

Allow functions with arguments

Macro processor can function like a simple compilerMacro processor can function like a simple compiler

In reality macro processor is just doing In reality, macro processor is just doing substitutions macro expansion


Macro SyntaxMacro Syntax

S t i Syntax is macro [, , ..., ]

endm ; ends macro definition

is the name of the macro Zero or more arguments Values assigned to arguments when macro is invoked are

substituted for the argument names in the macro body

Body may contain Assembly language mnemonicsy g g Assembler directives Macro directives (macro, local, exitm, endm only legal in macro)


Macro Example DefinitionMacro Example Definition

Macro definition is#include 18F452.INC;; Compare register aReg to a constant aConst and; jump to aDest if register value >= constant.; jump to aDest if register value > constant.;mCmpJge: macro aReg, aConst, aDest

movlw aConstsubwf aReg, wb fbtfsc status, carrygoto aDestendmendm


Macro Example InvocationMacro Example Invocation

When invoked (called) by:mCmpJge switchVal, maxSwitch, switchOn

it will produce (expand to):p ( p )movlw maxSwitchsubwf switchVal, wbtfsc status, carrygoto switchOn


Relocatable Object Filesj


Relocatable Object FilesRelocatable Object Files

Assembled (or compiled) object files with no associated absolute load addresses

Required for Building pre-assembled object libraries with MPLIBBuilding pre assembled object libraries with MPLIB Linking assembly language and C language modules

Compiler output will be relocatable

Specify the segment (or section) for placement of p y g ( ) peach part of the linker output, rather than absolute addresses


Relocatable Object Files: Assembler DirectivesRelocatable Object Files: Assembler Directives

So we need directives to work with Projects with multiple assembly language files Placing information into Program or Data MemoryPlacing information into Program or Data Memory Relocatable Object Files

Here they are


Directives for Object File Imports/ExportsDirectives for Object File Imports/Exports

EXTERN: Declare an Externally Defined Labelextern [, . ..][, ] Use when generating relocatable object file Similar to C/C++ extern declare a label (name

of subroutine etc) that is declared outside theof subroutine, etc) that is declared outside thefile being assembled Resolved by the linker

GLOBAL: Export a Label to Linkerglobal [ ]global [,] Use when generating relocatable object file Declare a label (name of subroutine, etc) to

make it visible outside the file being assembled Resolved by the linker


Directives for Object File Memory SegmentsDirectives for Object File Memory Segments

CODE: Begin an Executable Code Segment[] code [][ ] [ _ ] If unspecified, defaults to .code Starting address initialised to ,

or at link time if no address specifiedor at link time if no address specified

UDATA: Begin Un-initialised Data Segmentg g[] udata [] If unspecified, defaults to .udata Declares a segment of Un-initialised data Starting address initialised to ,

or at link time if no address specified



UDATA_ACS: Begin Object File Un-initialised DataSegment in Access RAM

[] udata_acs [] If unspecified, defaults to .udata_acs Declares a segment of Un initialised data in Declares a segment of Un-initialised data in

Access RAM Starting address initialised to ,

t li k ti if dd ifi dor at link time if no address specified

UDATA_OVR: Begin Object File Un-initialised Data_ g jOverlay Segment

[] udata_ovr []If l b l ifi d d f lt t d If unspecified, defaults to .udata_ovr Un-initialised data in this segment is overlayed

with all other data in udata_ovr segments of th


the same name


UDATA_SHR: Begin Object File Un-initialised DataSegment in Unbanked RAM

[] udata_shr [] Use when generating relocatable object file If unspecified defaults to d t h If unspecified, defaults to .udata_shr Declares a segment of Un-initialised data in

unbanked RAM Starting address initialised to ,

or at link time if no address specified


Directives for (Relocatable) Memory SegmentsDirectives for (Relocatable) Memory Segments

IDATA: Begin an Object File Initialised Data Segment initialisedGlobals:idata[] idata []

LimitL: dw 0LimitH: dw D300Gain: dw D5

[ ] [ _ ] Use when generating relocatable object file If unspecified, defaults to .idata

L ti C t i iti li d t Flags db 0String db Y-Axis,0

Location Counter initialised to ,or at link time if no address specified Linker generates look-up table entry in ROM for

each entry. User must add initialisation code tocopy values from ROM to RAM. See IDATA.ASM


Relocatable Program Memory SegmentsRelocatable Program Memory Segments

Location of executable code: Absolute: Use an org directive to locate code at an

absolute addressabsolute address

R l t bl D l d t d ll th Relocatable: Declare a code segment and allow the linker to calculate the address

Valid address ranges specified in a Linker Script File


Relocatable Data Memory SegmentsRelocatable Data Memory Segments

Data (variables) can be assigned to 1 of 5 segments: udata udata_acs

Each Un-initialised udata_ovr udata_shr

Each Un-initialised

idata Initialised (at least potentially)

The linker will place each of these in RAM, at l ti ifi d b li k fillocations specified by a linker file, xxx.lkr


Un initialised Data Memory SegmentsUn-initialised Data Memory Segments

D t t d i f th t i t i iti li d Data stored in any of these segments is not initialised Can only be accessed through:

b l ( i bl ) d l d i h Labels (variable names) declared in the segment Indirect addressing

udata ordinary Un-initialised data udata acs access data placed in Access RAM udata_acs access data - placed in Access RAM udata_ovr overlaid data

Used for variables that can be placed at the same addresses Used for variables that can be placed at the same addresses because they exist at different, non-overlapping times

udata shr shared data placed in RAM that is not udata_s s a ed data p aced t at s otbanked, or can be accessed in all banks Not used in PIC18


idata Initialised Data Memory Segmentidata Initialised Data Memory Segment

Data elements in idata are initialised given initial values Use the DB, DW, or DATA directives

Q ti i RAM t h d th i iti l Question: idata is a RAM segment, so where do the initial values come from?


idata Initialised Data Memory Segmentidata Initialised Data Memory Segment

The linker generates and populates a table (the _cinit table) that contains an entry for each initialised data elementthat contains an entry for each initialised data element

Table begins with a 16-bit number num_init that stores the number of initialised data elementu be o t a sed data e e e t

Each table entry has three 32-bit integers that store The from address in ROM (FLASH) The to address in idata RAM The size in bytes of the data element

User code must copy each from to the corresponding to at run-time but before the main code executestime, but before the main code executes

See the examples in IDATA ASM and c18i cMPASM Assembler :: Slide 62 of 69David Rye :: MTRX 3700

See the examples in IDATA.ASM and c18i.c

Example Data SegmentsExample Data Segments

F th fil t d b MPASM From the .lst file generated by MPASM:00020 IDATA

000000 00 00021 HistoryVector DB 000022 00023 UDATA000 3 U

000000 00024 InputGain RES 1000001 00025 OutputGain RES 1

00026Name of this segment

00026 00027 Overlay1 UDATA_OVR

000000 00028 Templ RES 1000001 00029 Temp2 RES 1000001 00029 Temp2 RES 1000002 00030 Temp3 RES 1

00031 00032 Overlay2 UDATA OVR

Segment type

00032 Overlay2 UDATA_OVR000000 00033 Hempl RES 1000001 00034 Hemp2 RES 1


The Linker (MPLINK) andLibrarian (MPLIB)Librarian (MPLIB)


The Linker MPLINKThe Linker MPLINK

L t d d d t Gi l t bl bj t Locates code and data Given relocatable object code and linker script, places code and data in memorymemory

Resolves addresses calculates absolute addresses of external object modulesof external object modules

Generates an executable a .HEX file of specified f tformat

Configures (software) stack size and location Identifies address conflicts Produces symbolic debug information allows the Produces symbolic debug information allows the

use of symbols for variables, functions, rather than addresses.


MPLINK InputsMPLINK Inputs

.o Relocatable object filesj .lib Collections of relocatable object files

Usually grouped in a modular fashion Usually grouped in a modular fashion Only used modules are linked into the executable

lk Li k i t fil t ll th li k .lkr Linker script files tell the linker What files to link Range of valid memory addresses for a particular target


MPLINK OutputsMPLINK Outputs

.cof Intermediate COFF (Common Object File Format) file Contains symbolic debug information

.hex Binary executable file No debug information Intel HEX format / 8-bit split format / 32-bit HEX format

.lst List file containing original source and final binary listings

.map Load map, showing memory use after linkingp p g y g Identify absolute addresses of globals, functions


Linker Script File (xxx lkr)Linker Script File (xxx.lkr)

// Sample linker command file for the PIC18F452 processor// when used **with***** the MPLAB ICD2

// Search for Libraries in the current directory.LIBPATH .

// CODEPAGE defined memory regions are in Program Memory, and are used for

Searchpath

Names of differentCODE segments

// CODEPAGE defined memory regions are in Program Memory, and are used for // program code, constants (including constant strings), and the initial values// of initialised variables.

CODEPAGE NAME=vectors START=0x000000 END=0x000029 PROTECTED Only usableCODEPAGE NAME=page START=0x00002A END=0x007DBFCODEPAGE NAME=debug START=0x007DC0 END=0x007FFF PROTECTEDCODEPAGE NAME=idlocs START=0x200000 END=0x200007 PROTECTEDCODEPAGE NAME=config START=0x300000 END=0x30000D PROTECTED

by code that requests itCODE

#pragma codeCODEPAGE NAME=devid START=0x3FFFFE END=0x3FFFFF PROTECTEDCODEPAGE NAME=eedata START=0xF00000 END=0xF000FF PROTECTED


Linker Script File (xxx lkr) (continued)Linker Script File (xxx.lkr) (continued)

// ACCESSBANK defined memory regions in Access RAM, used for data (variables).// DATABANK defined memory regions in Banked RAM, used for data (variables).// The names gpr0, grp1, etc here are **arbitrary**.gp , g p , yACCESSBANK NAME=accessram START=0x000 END=0x07FDATABANK NAME=gpr0 START=0x080 END=0x0FFDATABANK NAME=gpr1 START=0x100 END=0x1FFDATABANK NAME=gpr2 START=0x200 END=0x2FFDATABANK NAME=gpr3 START=0x300 END=0x3FFDATABANK NAME=gpr4 START=0x400 END=0x4FFDATABANK NAME=gpr5 START=0x500 END=0x5F3DATABANK NAME=dbgspr START=0x5F4 END=0x5FF PROTECTED

Access RAM

ACCESSBANK NAME=accesssfr START=0xF80 END=0xFFF PROTECTED

// Logical sections specify which of the memory regions defined above should// be used for a portion of relocatable code generated from a named section in // h d h l d i i d fi d// the source code. Each SECTION places a named section into a defined memory// region. Code sections are named using (for example) a // xxxx CODE directive in an assembly language source file OR// #pragma code directive in a C source file.

SECTION NAME=CONFIG ROM=config


Linker UsageLinker Usage

See MPLINK Users Manual for Much more detail Many examples


The Librarian MPLIBThe Librarian MPLIB

Allows construction & maintenance of object libraries Runs from the command line (DOS Window)

Syntax isSyntax is mplib [/q] /{ctdrx} Library [Member...]

wherewhere q: Quiet mode c: Create Library with Member[s]c: Create Library with Member[s] t: List table showing Library members d: Delete Member[s] from Libraryd: Delete Member[s] from Library r: Add/replace Member[s] in Library x: Extract Member[s] from Library


[ ] y

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05. Assembler