SW500005 - Microchip Technology

Three Award-Winning Compilers in One

Inside this Issue

Design Tip:

Give Your Project the

Boot!

Embedded Systems

Conference

Tech Tip:

Beware the Buffer

Overflow

Upgrade Now:

Latest Compiler

Versions

HI-TECH C

Powering On...

Coming Up...

initialization code for on board

peripherals.

A release candidate of HI-TECH C

for Holtek MCU is currently

undergoing verification ahead of the

final release of this new compiler in

early 2005. With support for the full

Holtek MCU family, this compiler

features the latest in code

generation technology that

streamlines programming, yet

delivers outstanding code density.

The compiler driver and debug

output integrates with Holtek's

development tools making

development a breeze.

For more information on these

upcoming compilers, contact one of

our sales offices or email us on

sales@htsoft.com

JANUARY 2005

HI-TECH Software’s PICC Enterprise Edition is the only

compiler package available with comprehensive support for all

10/12/14/16/17/18 series PICs and also the new dsPIC processors.

PICC Enterprise Edition is a low-cost package that unites our successful

PICC, PICC-18 and dsPICC compilers.

With the choice of over 300 different PIC processors, deciding which

one to use is a challenge. Even when you do decide, changing project

requirements during development often call for a larger or more

sophisticated chip. A change in processor can also mean buying a new

compiler… until now!

With HI-TECH Software’s PICC Enterprise Edition, there is finally a

single product that supports ALL of Microchip’s PICmicro processors.

Not only does this simplify which compiler to choose, it also eases

migration between processors by having a familiar tool-set.

PICC Enterprise Edition is particularly advantageous to existing PICC, PICC-18 and dsPICC customers

as the package is a cost-effective way of keeping all of your compilers up-to-date through a single

license option. Best of all, upgrades to the full PICC Enterprise Edition are at a special price!

With the strong relationship between HI-TECH Software and Microchip, you can be assured that the

PICC Enterprise Edition will be the first to support Microchip’s devices as they become available.

For further information or to download a demo, go to www.htsoft.com/products/eepiccompiler.php

News

HI-TIDE

HOLTEK

HI-TECH Software proudly

supports the Microchip brand with

high-quality C compilers. Beta 1 of the HI-TIDE v3.xx

series was released on November

2, 2004. This is available for PICC

compiler owners with extended

support and those who own the

PICC Enterprise Edition. As the first

in a series of releases to provide a

quality HI-TECH IDE (HI-TIDE) for

our compilers based on Eclipse,

Beta 1 is targeted at the PICC

compiler and allows project

management, incremental builds,

colour coded editing and CVS

support.

Beta 2 is set to be released in the

New Year with a number of user

interface improvements and initial

implementation of the C Wiz code

wizard for PICC. C Wiz is a

development tool that provides

NEW!

With flash memory becoming more readily

available in microcontrollers, the possibility of

software updates in applications can now be more

easily realized. This article is a brief outline on

how to develop a bootloader for a Microchip PIC

processor (16F87x). The same procedure,

however, could be applied to many other types of

processors (8051, ARM, MSP430, etc.).

Before any coding starts, you should first think

about how things are going to be positioned in

program memory. Since the bootloader needs

control after reset, it will need to use the reset

vector. Since it would be nice to make it easy to

build bootloader compatible programs, it is best if

the bootloader is positioned entirely at the start of

memory, or, all at the end of memory. On mid-

range PICs, the regular interrupt vector is located

at address 0x4. If the bootloader was going to be

positioned entirely at the start of memory, it would

then have to redirect the interrupt vector to the

downloaded program. Since this would add

complexity to the code and latency to the vector,

the bootloader will be positioned at the end of

memory. The reset vector will still be needed, so

this will mean shifting the downloaded program's

reset vector elsewhere.

In Figure A, typically the reset vector contains

instructions to jump into the main program. As the

bootloader needs the reset vector, you must move

the downloaded program's reset vector

elsewhere. Figure B shows how the reset vector

now points to the bootloader code and the

downloaded program's reset vector will be

positioned to an address just before the

bootloader.

• On reset the bootloader will take control and

prompt the user to send a hex file. It will wait

here (with count down) for a configurable

number of seconds.

• If no hex file is sent, the bootloader will

assume that no update is required and it will

jump to the redirected reset vector which in

turn will run the previously downloaded

program. If no program has ever been

downloaded, the redirected reset vector will

simply contain a jump to the beginning of the

bootloader and the whole process will start

again.

• If a HEX file is sent to the bootloader within the

count down period, it will start interpreting the

data and writing it to program memory. The

bootloader will look for addresses less than

0x4 (reset vector) and will instead write this

elsewhere. It will also ignore addresses

conflicting with those used by the bootloader,

thus protecting itself from being overwritten.

This bootloader is suitable for the following

processors: 16F870, 16F871, 16F873, 16F873A,

16F874, 16F874A, 16F876, 16F876A, 16F877,

16F877A. All source code, documentation and a

sample download program is included with the

latest version of the compiler. There is also further

information on HI-TECH Software’s online forums

at www.htsoft.com/support/forums.php

Design Tip: Give Your Project the Boot!

Page 2

The diagram above shows the memory map of a

program with and without the bootloader installed.

HI-TECH Software Booth Number: 411

350 leading companies showcasing cutting edge hardware,

software, tools, and the full spectrum of systems components.

Stop by HI-TECH’s booth in the exhibits area to learn more about

our industrial-strength software development tools and C compilers.

For more information on this event, go to www.esconline.com/sf

How it Works:

The phrase "buffer overflow" is almost making it into the mainstream press these days, but many

people who write programs which exhibit these mythical beasts are even unaware of what they are or why

they are a problem.

Tech Tip: Beware the Buffer Overflow

Page 3

Here's a buffer overflow. The constant array named greet actually

contains 6 characters, which strcpy() tries to copy into buffer where

there is only room for 5. What will probably happen is that the last

character (the invisible '\0' that terminates the string "hello") will be copied

into the space formerly known as precious, and the assumption that

precious contains the 7 we put into it will be violated.

#include <string.h>

main() {

const char greet[] =

"hello";

char buffer[5];

char precious = 7;

strcpy(buffer,

greet);

/* assume precious==7

}

#include <string.h>

main() {

const char greet[5] = "hello";

char buffer[6];

char precious = 7;

strcpy(buffer, greet);

memcpy(buffer, greet,

sizeof buffer);

}

Now we've fixed the first problem by making buffer big enough

to hold all of greet, the strcpy() is then broken because greet

is smaller. "How?" you ask. By making greet into a char array

that is not a string, i.e. a char array that has no terminating '\0'.

The strcpy() now will not know where to stop, and will keep

copying until it finds a zero byte, if that ever happens.

The memcpy() is better, because it is guaranteed to stop, but it

still does (possibly unquantifiable) Bad Things, as it tries to copy

from one byte past the end of greet.

A word of warning: do not assume strncpy() will save you: it is, unfortunately, not simply a bounded

version of strcpy(), and has its own set of fangs. Most significantly, unlike all the other str...()

functions in the Standard Library, it will not necessarily give you back a NUL-terminated string even if

you give it one to work with. If its source is a long but valid string, and its destination is a shorter buffer, it

will fill the buffer with characters from the string but it will NOT terminate that buffer with a '\0'.

#include <stdio.h>

main() {

char buffer[5];

gets(buffer);

fgets(buffer, sizeof

buffer, stdin);

}

The line with gets() might not be a buffer overflow, if the user (or

wherever gets() is getting its input from) enters at most 4 characters

before a newline; gets() cannot tell that it is not allowed to write past

buffer[4]. The line with fgets() can never overflow its buffer. Note,

though, that fgets() does not eat the '\n' like gets() does.

There are many more possible ways to overflow a buffer, writing data in all sorts of places it was never

meant to go. Sometimes the effect might not be noticeable, but you can never be sure. And while the

humble string or character array is the most common target, buffer overflows are not type-bigots - they

will strike anything they can touch.

When hunting them, the first thing to look for is functions which write into arrays without any way of

knowing the amount of space available.

If you get to define the function, you can pass a length parameter in or ensure that every array you ever

pass to it is at least as big as the hard-coded maximum amount it will write.

If you are using a function someone else (say, the compiler vendor) has provided then avoiding

functions like gets(), which take some amount of data over which you have no control and stuff it into

arrays they can never know the size of, is a good start.

Make sure that functions like the str...() family which expect NUL-terminated strings actually get

them - store a '\0' in the last element of each array involved just before you call the function, if

necessary.

Good hunting

To Slay the Monster

A Spotter’s Guide

Upgrade Now: Latest Compiler Versions

Page 4

HI-TECH Software LLC 6600 Silacci Way Gilroy, CA 95020 USA HI-TECH Software PO Box 103, Alderley, QLD 4051, Australia Web: http://www.htsoft.com

Ph: 800 735 5715 Fax: 866 898 8329 Ph: +61 7 3552 7777 Fax: +61 7 3552 7778 Email: sales@htsoft.com

Compiler Version

68000 C Cross Compiler V7.21

68HC05 C Cross Compiler V7.80

68HC11 C Cross Compiler V7.80

8051 C Cross Compiler V9.01

ARClite C Cross Compiler V7.85PL1

dsPICC Compiler V9.50

H8/300(H) C Cross Compiler V7.80

HI-TECH C for ARM V9.12

Compiler Version

HI-TECH C for msp430 V9.01

HI-TECH C for XA V7.73PL1

PICC Compiler V8.05PL2

PICC Enterprise Edition V2005

PICC-18 Compiler V8.35PL2

Salvo for 8051/msp430/PICs V3.2.3

Z80/Z180 C Cross Compiler V7.80PL2

With a renowned reputation in the control industry, Foxboro

SCADA Australia sees its primary focus as developing world-class

Supervisory Control and Data Acquisitions (SCADA) systems. For over

15 years, Foxboro has been using HI-TECH C to design and develop

software for Remote Terminal Units (RTUs), which are installed into

numerous large power substations - including those of Powerlink

Queensland in Australia and Transpower in New Zealand.

Working under strict validation and verification regimes, HI-TECH C was

selected as the best software to address these requirements. “With high

quality, low-cost software and readily available access to expert technical

support - who else would we have chosen for the job,” states Colin

Weaver, Senior Software Engineer of Foxboro. “All the hardware

designers and embedded software engineers in the company have had

Foxboro’s Remote Terminal

Unit Development Team

This enduring and successful relationship between HI-TECH Software and Foxboro is set to continue for

many more years to come. As Foxboro looks into developing new generations of hardware, they are

adamant with maintaining their HI-TECH C compiler-based designs.

For more on what our customers say, go to www.htsoft.com/news/testimonials.php

For more information, go to www.htsoft.com/updates

HI-TECH C Powering On...

some form of contact with HI-TECH Software’s tools and are extremely pleased and comfortable with

using HI-TECH C compilers. We are particularly impressed with and heavily use the remote debugger

feature.”

Check the Tech!

HI-TECH Software’s online forum is where over 3,000 members from around the world come to

discuss and get support with all issues related to our products. Go to www.htsoft.com/forum