Raspberry Pi Forums

Bakul Shah

For that reason "*p++ = *p++ + y" can't be converted to "*p++ += y". In C, at least, it can. You have two assignments to p with no intervening sequence point there, so the behaviour is undefined, and the compiler can emit whatever it likes. Good catch! But there is such a thing ...

Bakul Shah

... I've seen a compiler take "x += y" and calculate the address of x twice, and it was a complex array access so non-trivial. OK, when I switched on optimisation it got it right, but it would have worked just as well with "x = x + y". Yikes! That's a compiler error. What if the...

Bakul Shah

Or are you saying that . is a low level operator? I believe that CAR, CDR, CONS are the lowest level operators, and that . is in fact a function of the input parser and output formatter. Indeed. The low level memory allocator in a pure lisp (i.e. one without additional low level data types like arr...

Bakul Shah

Lisp is stack based, and thus slower and slower as you build it up. Actually most programming languages are "stack based". If anything Lisp is far less stack based than C/C++, Pascal, Fortran, Ada, etc. etc. etc because it supports first class functions (basically a function can be used o...

Bakul Shah

Just curious. How long does it take to compile the RPi linux kernel on an RPi? And to cross compile on a fast Intel/amd 64bit processor? And can you cross-compile a kernel for another platform on the RPi? For comparison, here are some plan9 numbers: rpi; pwd /sys/src/nix/k10 #time to cross compile a...

Bakul Shah

commercial product that employs a re-sold microprocessor board... a big issue is warranty costs and warranty pass-through. No to mention that the RPi may be suboptimal in other ways: power use, form factor, needing to put your electronics on a separate board, limited interface bandwidth in that cas...

Bakul Shah

Alan Perlis once quipped that a Lisp programmer knows the value of everything but the cost of nothing. More or less the same can be true of anyone who only uses high level languages. If you want to find out how much some part of your program costs in terms of space or cpu cycles, it helps to look at...

Bakul Shah

Ok, guys & girls, how about a programming challenge to settle this once and for all ? [Yeah, right!] Program it in the language of your choice to show off your programming chops! The challenge: Write a program that places the *minimum* number of knights on a chessboard such that a given square e...

Bakul Shah

You plug your original Pi power supply (male micro USB) into the switch. Then use a standard USB->micro-USB from the switch to the Pi's power port. The GPIO pins are only used for communication, not powering the Pi. One lead sends a signal to the Pi and the other lead receives a signal from the Pi....

Bakul Shah

In practice you can get away not knowing a lot of the theory but the parsing theory is not exactly simple. Check out the "Dragon book" on compilers! I am very familuar with the 'Dragon Book": Principles of Compiler Design . Two things about your statement: 1) The dragon book presents...

Bakul Shah

Angels and pinheads. I first wrote an interpreter for BASIC more years ago than I care to remember. It was limited to 26 variables, rather imaginitively called A to Z. I programmed it into a 2708 EPROM (I also had to create the hardware to program the EPROM). Less than 2000 bytes for the interperte...

Bakul Shah

Each month, I concatenate the 30 or 31 files into a single file. This is done at a Windows Command Window by navigation to the directory on the mapped drive, and typing the following command, for example, for January 2013: type 201301??.txt >> 201301.txt So here is the "interesting little diff...

Bakul Shah

Parsing is presented as hard , in fact parsing is extremely simple. In practice you can get away not knowing a lot of the theory but the parsing theory is not exactly simple. Check out the "Dragon book" on compilers! And using a language that will hide everything and teach nothing is nons...

Bakul Shah

aTao, do watch Brett Victor's talk! What he is talking about is several levels above "semicolon expected". And it is heads and shoulders above Eclipse.

Bakul Shah

Start with a simple typed language and a recursive decent parser type compiler I beg to disagree. You want to leave parsing right out of it, and start by working on the syntax tree direct. Something lisp-like, a language that's already expressed in terms of a syntax tree, would be the best place to...

Bakul Shah

It seems to me that you need the ability to edit source code and issue commands. Those are two modes and two windows, unless you go back to line numbers. You can do "windows" in text mode; standard FORTH has the top two thirds of the screen as an editor window and the bottom as a scrollin...

Bakul Shah

Gert van Loo wrote:I recently counted them: I have 6 Pi-related HW projects in parallel which I am responsible for or have to look at on a regular basis.

Tell us more, Gert!

Bakul Shah

But doing a pull, does this update everything (binaries, the kernel, etc.), or just sources, or does it update userspace binaries but just kernel source, or what? Everything that is in /n/sources/plan9/ dir but note that only the 386 bits are built there at present. On the RPi you'll have to rebuil...

Bakul Shah

A plan 9 noob here; will this procedure update all the userspace binaries, etc., just the sources or what? How do I completely update everything? (Incidentally I tried to update the kernel and failed miserably; check the backlogs in #plan9, due to soft/hard FPU mismatches!) Standard plan9 sources n...

Bakul Shah

Florent wrote:I'll be happy to help him out and I'm waiting for my eLinux account request to be approved.

I got my acct. Liz will have her quid in a bit but it won't be very pro.

Bakul Shah

The bootloader obviously isn't intended for persistent programs. It's intended for use during the development phase, so that you won't have to copy your program/kernel to the SD card every time you have an update to evaluate. If you want it persistent, just replace the bootloader with your program ...

Bakul Shah

Your assuming that the current OS paradigm is broken, which isn't proved, in my mind anyway. For example, no-one has yet given me a good alternative, or at least explained the alternatives in the words of one syllable I need in order to understand 'paradigm shifts'. And until that happens, the curr...

Bakul Shah

I don't believe anyone has come up with an alternative. The existing file paradigm is pretty limiting, but I have seen nothing that gives the same unity and utility, much less a step change in expressibility or efficiency. Compared to unix the file paradigm has been taken much further in plan9[1]. ...

Bakul Shah

Kona is an open-source implementation of the K programming language. If you don't know APL, then this is the place to start. K is an ASCII-based APL. To build it on the Raspi: $ git clone https://github.com/kevinlawler/kona.git $ cd kona $ make To use: $ rlwrap ./k # rlwrap for history and command l...

Bakul Shah

There's also a ready made solution: http://www.pololu.com/catalog/product/751 , I'm not sure if it has the "hold for x seconds to do hard off" or not but in most cases you don't want to do a hard-off to avoid SD card corruption. The circuit I referenced earlier does this. You need an outp...

Search found 324 matches

Re: Assembly - any use in teaching it?

Re: Assembly - any use in teaching it?

Re: BASIC - more harmful than useful?

Re: BASIC - more harmful than useful?

Time to compile the kernel

Re: Is PI a good choice for prototyping a commercial product

Re: Assembly - any use in teaching it?

Re: BASIC - more harmful than useful?

Re: Power switch now available for Pi

Re: BASIC - more harmful than useful?

Re: BASIC - more harmful than useful?

Re: An interesting little difference in file handling ...

Re: BASIC - more harmful than useful?

Re: 'Visualizing Code to Fail Faster' - Inventing on Princip

Re: BASIC - more harmful than useful?

Re: BASIC - more harmful than useful?

Re: Gertboard, RISC OS and BASIC

Re: Keeping up to date

Re: Keeping up to date

Re: Quid pro quo

Re: Bootloader Questions

Re: Other ARM hardware?

Re: Other ARM hardware?

Re: APL

Re: RaspberryPi On/Off Switch Idea