How can i use "Plain C" to program Arduino without using the "Processing programming language"?
I want to improve my C programming skills by using it with Arduino for embedded systems.
I have very limited ability to code in C++, and I would love to write my own Arduino Library using "C", to avoid using classes and OOP.
Processing looks like Java to me, and i want to use "C pointers" to gain more practical knowledge.
The thing is that Arduino doesn't use Processing.
Processing is (was?) a separate programming language which was developed independently for a different purpose. The language resembles C and C++ very closely, so closely that it's almost identical.
Programming the Arduino, however, is accomplished using a (n unfortunate) mixture of C and C++, with a set of custom libraries (which are similar in style to that of Processing). These libraries are written in C and C++ themselves, and they are only good for making one's code more portable across different MCU types. Using them is not strictly necessary for programming the AVR MCU. In fact, the libraries have quite a few drawbacks (the code is big, inherently slow and ugly, amongst others).
If you want to use plain ol' C for programming the Arduino, then just go ahead and do so. Grab the reference PDF from Atmel's site for your particular MCU, learn the special registers (I/O, timers, etc.), install the avr-gcc toolchain on your computer, and use avr-gcc, avr-objcopy and avrdude to compile and install your programs.
There also happens to be a C-only library which follows this kind of convention. It doesn't provide as much abstraction as the stock Arduino library has, because it's lower-level, but you can have a look at it and see how one can accomplish basic algorithms without the default libraries.
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I am exposed to C because of embedded system programming, and I think it's one wonderful language in this field. However, why is it used to write compilers? If the reason why gcc is implemented in C/C++ is that there aren't many good languages at that time, there's no excuse for why clang is taking the same path (using C/C++).
Is it for performance reasons? Mostly interpreted languages are a bit slower compared with compiled languages, but I guess the difference is almost negligible in CoffeeScript (JavaScript), because of Node.js.
From the perspective of developers, I suppose it's much easier to write one compiler using high level languages. Unfortunately, most of compilers out there are written in C/C++. Is it just because of legacy code?
Response to comments:
Bootstrapping is just one way to illustrate that this language is powerful enough to write one compiler. It shouldn't the dominant reason why we choose the language to implement the compiler.
I agree with the guess given below, that "most compiler developers would answer because most of compiler related tools (bison, yacc) emit C code". However, neither GCC nor Clang use generated parser, they implemented one themselves. This front-end process is independent of targeting architecture, and should not be C/C++'s strength.
There's more or less consensus that performance is one key factor. Indeed, even for GCC and Clang, building a reasonable size of C project (Linux kernel) takes a lot of time. Is it because of the front-end or the back-end. I have to admit that I didn't have much experience on backe-end of compilers, as we finished the course on compiler with generated LLVM code.
I am exposed to C because of embedded system programming, and I think
it's one wonderful language in this field.
Yes. It's better than Java.
However, why is it used to write compilers?
This question can't be answered without asking the developers. I suspect that the majority of them will tell you that common compiler-writing software (yacc, flex, bison, etc) produce C code.
If the reason for gcc is that there aren't many good languages,
there's no excuse for clang.
GCC isn't a programming language, and neither is Clang. They're both implementations of the C programming language.
Is it for performance reasons?
Don't confuse implementation with specification. Speed is an attribute introduced by your compiler and your computer, not by the programming language. GCC happens to produce fairly efficient machine code, which might influence developers to use C as their primary programming language... but in ten years time, it could* be that node.js produces more efficient machine code than GCC. Don't forget, StackOverflow is forever.
* could, but most likely won't. See Ira Baxters comment below for more info.
Mostly interpreted languages are a bit slower compared with compiled
languages, but I guess the difference is almost negligible in
CoffeeScript (JavaScript), because of Node.js.
Similarly, interpretation or compilation isn't the choice of the language, but of the implementation of the language. For example, GCC and Clang choose to compile C to machine code. Ch and CINT are two interpreters that translate C code directly to behaviour, rather than machine code. Java was once predominantly translated using interpretation, too, but is now predominantly compiled into JVM bytecode. Javascript seems to be phasing towards predominant compilation, too. Who knows? Maybe you'll see compilers written predominantly in Javascript in ten years time...
From the perspective of developers, I suppose it's much easier to
write one compiler using high level languages.
All of these programming languages are technically high level. They're mostly defined in terms of an abstract machine; They're certainly not low level.
Unfortunately, most of compilers out there are written in C/C++.
I don't consider it unfortunate that C++ is used to write software; It's not a bad programming language.
Is it just because of legacy code?
I suppose legacy code might influence the decision of a programmer. In the end though, as I said, you'd have to ask the developers. They might just decide to use C or C++ because C or C++ is their favourite programming language... Why do you speak English?
Compilers are very complex software in general. The front end part is pretty simple (parsing), but the backend part (scheduling, code generation, optimizations, register allocations) involve NP-complete problems (of course compilers try to approximate solutions to these problems). Thus, implementing in C would help compile times. C is also very good at bitwise operators and other low level stuff, which is useful for writing a compiler.
Note that not all compilers are written in C though. For example, Haskell GHC compiler is written in Haskell using bootstrapping technique.
Javascript is async, which doesn't suit compiler writing.
I see many reasons:
There is no elegant way of handling bit-precise code in Javascript
You can't write binary files easily in Javascript, so the assembler part of the compiler would have to be in a more low-level language
Huge JS codebase are very heavy to load in memory (that's plain text, remember?)
Writing optimizing routines for compilers are heavily CPU-intensive, which is not yet very compatible with Javascript
You wouldn't be able to compile your compiler with it (bootstrap), because you need a Javascript interpreter behing your compiler. The bootstrap phase wouldn't be "pure":
JS Compiler compiles NodeJS -> NodeJS runs your new Compiler -> new JS Compiler
gcc is implemented primarily in C, but that is not true of all compilers, including some that are quite standard. It is a common pattern for a compiler to be implemented in the language that it compiles. ghc is written largely in Haskell. Recent versions of guile feature a compiler implemented mostly in Scheme.
nope, coffeescript et al are still much slower than natively-compiled (and optimised) C code. Even if you take the subset of javscript that is able to be optimised (asm.js) its still twice as slow as native C.
What you hear about when people say node.js is just as fast as C code means that its just as fast as part of an overall system that does other things like read from disk, wait for data off the network, etc. In these systems the CPU is underused (especially with today's superfast CPUs) so the performance problem is not the raw processing capability of the language. Hence, a node.js server is exactly as fast as a C server if they're both stuck waiting for a network call to return data. The type of system written in node.js does a lot of waiting for network which is why people use node.js. The type of system written in C does not suit being written in node.js
I have a project wherein i need to write an application for an USRP device. But the gnuradio software which i use to interact with the device driver and ultimately the hardware provides apis in c++ and python. I am comfortable programming in c and thus would like a way which would let me to call the apis from my c program.Is there a way in which i could do so? It would be a lifesaver.
C++ adds a lot to C, but doesn't take much away. Except for a few corner cases (which can be worked around) most valid C code is also valid C++ code, so you won't encounter many problems when you compile it as C++. Just write your whole project in a C style and only use C++ features where they are necessary to interface with the C++ API of gnuradio.
I'm looking for a higher-level system language, if possible, suitable for formal verification, that compiles to standard C, so that it can be run cross-platform with (relatively) low overhead.
The two most promising such languages I've stumbled during the past few days are:
BitC - While the design goals of this language match my needs (it even supports the functional paradigm), it is in very unstable state, the documentation is out of date, and, generally, it seems like a very long shot for a real-world project.
Lisaac - It supports Design-by-contract, which is very cool and has a relatively low performance overhead. However the website is dead, there hasn't been a new release since '08 and generally it seems the language is dead.
I'd also like to note that it's not meant for a real-time system, so a GC or, generally, non-determinism (in the real-time sense), is not an issue.
The project involves mainly audio processing, though it has to be cross-platform.
I assume someone would point me to the obvious answer - "plain ol' C". While it is truly cross-platform and very effective, the code quantity would probably be greater.
EDIT: I should clarify that I mean cross-platform AND cross-architecture. That is why I consider only languages, compiled to C in the first place, but if you can point me to another example, I'd be grateful :)
I think you may become interested in ATS. It compiles to C (actually it expresses and explains many C idioms and patterns from a formal type-theoretic perspective, it has even been proposed to prepare a book of sorts to show this -- if only we had more time...).
The project involves mainly audio processing, though it has to be cross-platform.
I don't know much about audio processing, I've been mainly doing some computer graphics stuff (mostly the basic things, just to try it out).
Also, I am not sure if ATS works on Windows (never tried that).
(Disclaimer: I've been working with ATS for some time. It is bulky and large language, and sometimes hard to use, but I very much liked the quality of programs I've been able to produce with it, for instance, see TEST subdirectory in GLES2 bindings for some realistic programs)
The following doesn't strictly adhere to the requirements but I'd like to mention it anyway and it is too long for a comment:
Pypy's RPython can be translated to C. Here's a nice talk about it. It's been used to implement Smalltalk, JavaScript, Io, Scheme, Gameboy (with various degree of completeness), but you can write standalone programs in it. It is known mainly for its implementation of Python language that runs on Intel x86 (IA-32) and x86_64 platforms.
The translation process requires a capable C compiler. The toolchain provides means to infer various things about the code (used by the translation process itself) that you might repurpose for formal verification.
If you know both Python and C you could use cython that translates Python-like syntax to C. It is used to write CPython extensions.
There are a lot of excellent answers how can one simulate object oriented concepts with C. To name a few:
C double linked list with abstract data type
C as an object oriented language
Can you write object-oriented code in C?
When is it appropriate to use such simulation and not to use languages that support object-oriented techniques natively?
Highly related:
Why artificially limit your code to C?
https://stackoverflow.com/questions/482574/whats-the-advantage-of-using-c-over-c-or-is-there-one
I'll give you the one reason I know of because it has been the case for me:
When you are developing software for a unique platform, and the only available compiler is a C compiler. This happens quite often in the world of embedded microcontrollers.
To just give you another example: a fair amount of the x86 Linux kernel is using C as if it were C++, when object-orientation seems natural (eg, in the VFS). The kernel is written in assembly and C (if that wasn't changed in the 3.0 kernel). The kernel coders create macros and structures, sometimes even named similar to C++ terms (eg, for_each_xxx), that allow them to code as-if. As others have pointed out, you'd never choose C if you start a heavily object-oriented program; but when you're adjusting C based code to add object-oriented features, you might.
When you want a cross-platform foundation for object-oriented APIs. A case in point is Apple's Core Foundation. Being entirely C, it could be easily ported, yet provides an extremely rich set of opaque objects to use.
A nice example of its flexibility is the way many of its types are 'toll-free' bridged with those from Foundation (a set of true OO Objective-C libraries). Many types from Core Foundation can be used, fairly naturally, in Foundation APIs, and vice-versa. It's hard to see this working so well without some OO concepts being present in the Core Foundation libraries.
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Why is C used for writing drivers and OS codes?
Is there a size problem?
Are there any drivers written in other languages?
Which language were XP, Vista, and Solaris written in?
C compiles down to machine code and doesn't require any runtime support for the language itself. This means that it's possible to write code that can run before things like filesystems, virtual memory, processes, and anything else but registers and RAM exist.
In safety-critical environments (think avionics, spacecraft, medical devices, transportation, control software for process control), systems (as well as drivers) are often written using Ada or even SPARK/Ada.
To clarify: C is usually understood to be fairly low level, and pretty much like a "macro language" for assembly itself, that's also where its power is coming from (speed, size, portability).
Ada, on the other, hand has been specifically designed for safety-critical applications with verifiability in mind, to quote Ada 2005 for Mission-Critical Systems:
Ada [9] is the language of choice for many critical systems due to its careful design and the existence of clear guidelines for building high integrity systems [10]
That's also where Ada's support for strong typing comes in, as well as a number of other important features (quoting design for safety):
Programming languages differ wildly in
their appropriateness for use in
safetyrelated systems. Carré et al.
identified six factors that influence
the suitability of a language for
high-integrity applications [Carré
1990]. These are:
Logical soundness
Complexity of definition
Expressive power
Security
Verifiability
Bounded time and space constraints
No standard programming language performs
well in all these areas although some
(such as Pascal and Ada) perform much
better than languages such as C or
C++. In highly critical applications
‘verifiability’ is of great
importance. Certain languages allow
powerful software verification tools
to be used to perform a wide range of
static tests on the code to detect a
range of programming errors.
[...] An
important issue in the selection of a
programming language is the quality of
the available compilers and other
tools. For certain languages validated
compilers are available. While not
guaranteeing perfection, validation
greatly increasing our confidence in a
tool. Unfortunately, validated
compilers are only available for a
limited number of languages, such as
Ada and Pascal. In addition to
compilers, developers of critical
systems will make use of a range of
other tools such as static code
analysis packages. The static tests
that can be performed on a piece of
code vary greatly depending on the
language used. To aid this process it
is common to restrict the features
that are used within certain languages
to a ‘safe subset’ of the language.
Well structured and defined languages
such as subsets of Ada, Pascal and
Modula-2 allow a great many tests to
be performed such as data flow
analysis, data use analysis,
information flow analysis and range
checking. Unfortunately many of these
tests cannot be performed on languages
such as C and C++ .
It would be really beyond the scope of this question to go into even more detail, but you may want to check out some of the following pointers:
Ada compared to C and C++
Ada vs. C
Quantifying the Debate: Ada vs. C++
Why choosing Ada as a teaching language? (Ada vs. C in University)
Comparing Development Costs of C and Ada (summary)
C / C++ / Java Pitfalls
& Ada Benefits
Is Ada a better C?
Ada, C, C++, and Java vs. The Steelman
Ada: Dispelling the Myths
Real-time programming safety in Java and Ada
If anyone wants to look into Ada some more, check out this: Ada Programming (wikibooks)
There are even programming languages that are specifically developed for highly critical applications, such as JOVIAL or HAL/S, the latter of which is used by the space shuttle program.
Is there any drivers written in any other languages?
I have seen some Linux drivers for special hardware being written in Ada, don't know about other operating systems though. However, such drivers usually end up wrapping the the C API.
Because C has the best combination of speed, low memory use, low-level access to the hardware, and popularity.
Most operating systems have a kernel written in C, and applications on top of that written in either C, C++, C# or Obj-C
C is by far the easiest language(other than assembly) to "get going" on bare bones hardware. With C, (assuming you have a 32bit bootloader such as GRUB to do the hard mode switching) all you must do is make a little crt0.asm file that sets up the stack and that's it(you get the language, not including libc). With C++ you must worry about dynamic casts, exceptions, global constructors, overriding new, etc etc.. With C# you must port the .Net runtime(which on it's own basically requires a kernel) and I'm not sure about Obj-C, but Im sure it has some requirements also...
C is simply the easiest language to use for drivers. Not only is it easy to get started with, but also it's easy to know exactly what happens at the machine level. Their is no operator overloading to confuse you and such. Sure it's handy in a "good" environment, but in Ring 0 where a bad pointer not only crashes your application, but usually results in a triple fault(reboot), blue screen, or kernel panic. You really like knowing what goes on in your machine..
"why we are using C language for writing drivers and OS codes.?"
So that programmers won't have to learn new syntax of each new assembly language for each new kind of machine.
"Is there any drivers written in any other languages?"
Historically, assembly languages. I don't remember if PL/S or BLISS could be used for drivers. Maybe B. In modern times, a few brave people use C++ but they have to be very careful. C++ can be used a bit more easily in user mode drivers in some situations.
Lisp machines had their operating systems written in Lisp, which shows that you don't have to use C or assembly. The Lisp machine business was destroyed by the availability of cheap PCs, whose operating systems were of course written in C and assembly.
C was one of the very first languages (that wasn't assembly) that was suitable for writing operating systems, so it caught on early. While other languages have appeared since that are also suitable for writing operating systems in, C has remained popular perhaps due to its long history and the familiarity programmers have with its structure and syntax.
C is also a language that teaches a lot about memory management and is low-level enough to show the barrier between hardware and software. This is something that is rare among many methodologies today, that have grown more towards abstraction way above anything at the hardware level. I find C is a great way to learn these things, while being able to write speedy code at the same time.
Remember that C was originally developed for writing operating systems (in this case - Unix) and similar low-level stuff. It is wery close to the system architecture and does not contain any extra features that we want to control, how they exactly work. However, please note that the rest of the operating system, including the programming libraries, does not have to be written in the same language, as the kernel. The kernel functions are provided through a system of interrupts and in fact such programming libraries can be written in any language that supports assembler snippets.
The most popular operating system nowadays are written in C: Windows, Linux and many other Unix clones, however this is not the rule. There are some object-oriented operating systems, where both the kernel and the programming interface are written in an objective language, such as:
NeXTSTEP - Objective-C
BeOS - C++
Syllable - C++
See: Object-oriented operating system on Wikipedia
Note that in Linux, it is possible to write kernel drivers in the languages other than C (however, it is not recommended). Anyway, everything becomes a machine code when it comes to running it.
"C compiles down to machine code and doesn't require any runtime support for the language itself."
This is the best feature of C
It's my belief that languages like Python, Java, and others are popular mainly because they offer extensive standard libraries that allow the programmer to code a solution in less lines. Literally a ruby programmer can open and read a file in one line where in C it takes multiple lines. However beneath this abstraction are multiple lines. Therefore the same abstraction be done in C and it's recommended. Oddly it seems the C philosophy is not to reduce the total lines of code so there is no organized effort to do so. C seems to be viewed as a language for all processor chips and naturally this means that it's hard to create any 'standard' abstracted one line solutions. But C does allow you to use #ifdef preprocessor commands so in theory you can have multiple variations of an implementation for multiple processors and platforms all on one header file. This can't be the case for python, or java. So while C does not have a fancy standard library it's useful for portability. If your company wants to offer programs that run on computers, embedded, and portable devices then C is your choice language. It's hard to replace C's usefulness in the world.
As another note for machines that have drivers in other languages, there is the SunSpot robotics platform. Drivers for devices that are connected (sensors, motors, and everything else that can communicate via the I/O pins) are written in Java by the user.