1amzave

16 ms·

91.
by 1amzave 15y ago
I'm kind of surprised GCC doesn't have a __builtin_* extension for overflow detection. It seems like a pretty natural fit among a lot of the other ones. ...and after a quick bit of googling, it appears this has been discussed by the GCC de
92.
by 1amzave 15y ago
Well, if you really want to go apples-to-oranges and specialize as much as possible for the sequentially increasing case we're dealing with here, you could just do your arithmetic directly on the ASCII string itself, complete with a littl
93.
by 1amzave 15y ago
You probably can: $ gdb /Applications/Safari.app/Contents/MacOS/Safari $PID iTunes, annoyingly, uses Apple's stupid little "please don't ptrace me" flag, which is a minor inconvenience, but fairly readily circumventable.
94.
by 1amzave 15y ago
OK, I just tested with gcc 4.6.0, and unless I've screwed something up, it looks like (at -O4) it actually optimizes these into the exact same code. As in the generated ELFs are byte-for-byte identical. Impressive.
95.
by 1amzave 15y ago
That runs in ~0.4s on my system (Xeon E5520, 2.27GHz), but replacing the 'digits' lookup table with simple arithmetic on the ASCII values ('0' + j%10) speeds it up to ~0.23s. Yes, L1 caches are pretty fast, but ALUs are still faster (for i
96.
by 1amzave 15y ago
In practical terms, does this differ significantly from killing the process and leaving a coredump?
97.
by 1amzave 15y ago
Well, the problem here is (assuming I'm understanding everything correctly) pretty specifically the combination of the comma operator and a bitfield. Of those two, I'd say the latter, even if superficially more intuitive, is probably the
98.
by 1amzave 15y ago
You must be a C++ user -- I (a C guy) immediately thought "what? No, that's in -Wextra, not -Wall", checked the man page to confirm, and sure enough, it differs (-Wall includes sign-compare when compiling C++, but not C).
99.
by 1amzave 15y ago
s/SIMD/SSE/, methinks. SIMD is a more general concept; SSE is a set of SIMD-style instructions (the second 'S' actually stands for SIMD).
100.
by 1amzave 15y ago
I found it to be quite buggy, however, so I built 4.00.03 from source and use that instead. (Lack of vertical split doesn't bother me very much.)
101.
by 1amzave 15y ago
> Well, the entire debate is about generating architecture-independent code, so that's a good example. It should be possible to generate optimized code for AMD and Intel using the same compiler. In practice, it doesn't really happen.
102.
by 1amzave 15y ago
I'm curious what you mean by your comments about the state of compilers. In what ways do current compilers suck? I assume you're not speaking in terms of utilizing virtualization instructions, since I'm having a hard time imagining a situa
103.
by 1amzave 15y ago
> Calling it from the empty string concatenates the pieces with no separator, which is a Python quirk and rather surprising at first. This is stated twice, but I can't make any sense of it. How is this even remotely surprising? What
104.
by 1amzave 15y ago
Well, as you say OSX has the keychain (which is encrypted, and has command-line access tools). I think most Linux systems have something similar ('keyctl' on my system). I know nothing of Windows, but I would hope something analagous exis
105.
by 1amzave 15y ago
A word of warning on Prey -- I looked into it myself and last I checked, it stores your email password unencrypted in a plain text file in your filesystem. Better still, a comment in the file describes it as "base64 encrypted". Sure, your
106.
by 1amzave 15y ago
I've heard "nasal demons" in some C circles (as in, "the compiler may cause demons to fly out your nose").
107.
by 1amzave 16y ago
> ...reference counting was pointed out to me and I realized it would be pointless -- the act of merely looking at an object changes the object, so copy-on-write means copy-everything. Hmm...might it be worthwhile to work around this
108.
by 1amzave 16y ago
Care to elaborate? Unlike signed ones, unsigned integral types at least have well-defined behavior on shifting and overflow. (I'm speaking in terms C specifically here, of course.)
109.
by 1amzave 16y ago
Circuit-level (layout) problems I'd guess make up a decent portion. I heard (from a guy who worked on it) about a bug in a prototype version of a processor from a major company that didn't cause any correctness problems but was a major per
110.
by 1amzave 16y ago
Modern compilers may actually do this as well, though for slightly different reasons -- GCC (at the right optimization level) likes to put branch targets and functions at aligned addresses, so you often end up with little pads of NOP instru
111.
by 1amzave 16y ago
I have a similar section in my .bashrc via a somewhat hackish loop (or two): ESC=$'\x1b' # Terminal color escapes colornames=(BLACK RED GREEN YELLOW BLUE MAGENTA CYAN) for i in ${!colornames[@]}; do eval "${colornames[$i]}=\"$
112.
by 1amzave 16y ago
From man bash, the variable PROMPT_COMMAND: If set, the value is executed as a command prior to issuing each primary prompt. e.g.: PROMPT_COMMAND='[[ "$PWD" =~ ^/sensitive/area ]] && PS1="be careful: " || PS1="normalpromp
113.
by 1amzave 16y ago
The tilde-escape offers significantly more than just termination, actually. Hit '~?' for the available escape sequences: Supported escape sequences: ~. - terminate connection (and any multiplexed sessions) ~B - send a BREAK t
114.
by 1amzave 16y ago
Related/competing: Xilinx's "Extensible Processing Platform", a SoC with dual Cortex-A9 cores + various hard-IP peripherals + FPGA fabric ( http://www.xilinx.com/technology/roadmap/processing-platform... ). I'm interested to see where these
115.
by 1amzave 16y ago
If high school memories serve, Latin has regular number-names for 11 through 17, but then semi-irregular ones for 18 ( duodeviginti , or "two from twenty") and 19 ( undeviginti , "one from twenty"). (I say semi-irregular because they're inc
116.
by 1amzave 16y ago
A few days ago I was wondering if the link between two remote hosts was 100Mbps or 1Gbps, and didn't have root access to run ethtool (sidenote: is there an easier way for an unprivileged user to determine this?), so out came netcat and dd:
117.
by 1amzave 16y ago
Nice article, though I'm not sure I quite agree with this (or perhaps the way it's phrased): > While it obviously can't stand up to the sort of abuse you could give a hard drive... I'd have said one of the main advantages of flash sto
118.
by 1amzave 16y ago
True, though until semi-recently SiCortex offered MIPS-based HPC/supercomputer systems -- sicortex.com has been offline for a while, but see: http://en.wikipedia.org/wiki/SiCortex
119.
by 1amzave 16y ago
I don't recall hearing any announced, though I wouldn't be surprised at all if it were currently in the works. The A15 mentioned in the article, however, I believe has something in the spirit of x86's PAE that offers an expanded (36 bits o
120.
by 1amzave 16y ago
So what languages did everyone use? I decided to try a different one on each level, so I used Python, bash (letting GNU coreutils 'factor' do the hard work), and Haskell, respectively.

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