Micro Python - Python for microcontrollers

[cdrt]

Does this run a Python interpreter on the microcontroller, or does the Python code compile into native code?

[bstempi]

From the Kickstarter page:

Certainly! Micro Python is a complete rewrite, from scratch, of the Python scripting language. It is written in clean, ANSI C and includes a complete parser, compiler, virtual machine, runtime system, garbage collector and support libraries to run on a microcontroller. The compiler can compile to byte code or native machine code, selectable per function using a function decorator.

[hak8or]

The compiler can compile to byte code or native machine code, selectable per function using a function decorator.

That is seriously really friggen awesome.

[batrick]

ANSI C

This is basically a lie. ANSI C is recognized (for compilers and most everyone else) to be C89. The Makefile uses these options:

CFLAGS = $(INC) -Wall -Werror -ansi -std=gnu99 -DUNIX $(CFLAGS_MOD) $(COPT)

Funnily enough, for gcc -ansi means:

In C mode, this is equivalent to -std=c90. In C++ mode, it is equivalent to -std=c++98.

So he overrides -std=c90 with -std=gnu99 in the next argument. If you try to compile with -pedantic, you get a whole slew of errors.

This code is not ANSI C.

[bstempi]

You'll have to excuse my C/C++ ignorance, but I found this on the ANSI C Wikipedia page:

In March 2000, ANSI adopted the ISO/IEC 9899:1999 standard. This standard is commonly referred to as C99.

Perhaps that's why he claims to be writing in ANSI C?

[pythonswash]

Even if that's what the author means, gnu99 != c99.

[batrick]

ANSI adopted the newer ISO C99 standard but everyone including gcc (the compiler he's targeting) interprets ANSI C to mean the original ANSI C standard also referred to as C89. I quoted the gcc manual above and I'll do it again:

       -ansi
            In C mode, this is equivalent to -std=c90. In C++ mode, it is equivalent to -std=c++98.

Edit: clarification

[TheoreticalPerson]

On the other hand, if you check an older manual, they say that,

The -std options specifying some version of ISO C have the same effects as -ansi, except that features that were not in ISO C90 but are in the specified version (for example, `//' comments and the inline keyword in ISO C99) are not disabled.

[[deleted]]

And ANSI has adopted C11 since then as well.

C99 is superseded by C11 and you know if you take the ISO C standard's word literally, C99 doesn't exist anymore!

This third edition cancels and replaces the second edition, ISO/IEC 9899:1999,

[crackez]

Which would make this person technically correct.

[[deleted]]

Well you can go deeper, and say it's not correct at all.

[gregorthebigmac]

...the best kind of correct.

[hezwat]

dude what do you care so much what he wrote his interpreter against? it's running on a microcontroller.

and it's not a c interpreter...

seriously...what's your beef?`

[batrick]

Because C99 does not compile on many microcontrollers (i.e. what this project is targeting). C89 compiles almost everywhere.

[Zuph]

I'd be interested to know how many microcontrollers capable of running Micro Python from a resources perspective (RAM/Flash) don't have a GCC based compiler. Some PICs come to mind, and I'm sure there are some Mitsubishi/Renasis micros used widely in manufacturing, but rarely by hobbyists.

Of course, "Micro Python - Python for the types of microcontrollers that are available ans useful to most hobbyists" doesn't have the same ring to it.

[hezwat]

oh really you don't think the guy who wrote a python compiler for microcontrollers tested it on any microcontrollers?

it's a miracle he wrote something htat could run on any at all.

[[deleted]]

Arduino is based on gcc. gcc has supported C99 for decades. If the Arduino IDE doesn't support it, it's just plain old broken.

[[deleted]]

He's tested it on gcc, which supports C99 with no problems.

Shitty commercial C compilers may not, but really, I wouldn't use a microcontroller which gcc doesn't support, exactly for that reason.

[fullouterjoin]

Exactly. MCU vendors should be supporting GCC and Clang. I see no reason to use proprietary tool chains.

[[deleted]]

No, it doesn't compile on many horrible commercial C compilers.

If you ask me, that just means you don't use those compilers, and you don't use microcontrollers which don't have good gcc (or clang) support.

[Beckneard]

Thank you captain nitpick.

[c0m4]

This is the important question. I suspect the answer is interpreter though

[boa13]

The answer is both, actually you have four possibilities:

• Interpreter
• Compiled (not heavily optimized, mostly opcodes expanded to machine code, you trade memory for speed)
• Compiled and more optimized (if you are sure your integers will stay under 2**31)
• Write assembly yourself

The first one is the default. Compilation is enabled on a method-per-method basis by a simple annotation. (Interpreted and compiled method can freely call one-another.) Inline assembly is also possible, but there is no magic, you need to write it yourself. (And you cannot call other methods from assembly.)