mansr

18 ms·

91.
by mansr 13y ago
I was involved in some NEON work on libjpeg-turbo, and I can confirm that the image buffer management there is hell, as are some other aspects of the design. A from-scratch implementation with performance in mind should easily be quite a bi
92.
by mansr 13y ago
The BeagleBone CPU is much faster than the RPi. The GPU is less sophisticated, but that hardly matters for your application.
93.
by mansr 13y ago
Note that the BeagleBone has a 100Mbps phy.
94.
by mansr 14y ago
This entire thread is specifically about C.
95.
by mansr 14y ago
That is how it has to be. Determining at compile-time whether a given program will invoke undefined behaviour at runtime is equivalent to solving the halting problem, which we know is impossible.
96.
by mansr 14y ago
The code in question comes from the reference implementation of the H.264 video codec. What scraps of code this was cobbled together from is anyone's guess.
97.
by mansr 14y ago
Good thinking. Most modern compilers will recognise abs() and generate efficient code.
98.
by mansr 14y ago
Nothing in the GPL prevents such uses.
99.
by mansr 14y ago
They are celebrating the 400-year anniversary of a historic battle. The opening of this package is but a small part of it.
100.
by mansr 14y ago
Most keyboards will withstand a washing just fine.
101.
by mansr 14y ago
http://gcc.gnu.org/ml/gcc/2000-01/msg00572.html
102.
by mansr 14y ago
If you don't cross-compile, I would say it's not an embedded platform.
103.
by mansr 14y ago
Sounds to me like AMD simply improved the yield in production such that they are confident increasing the clock rate on new chips. An old chip may or may not be good enough to run at the higher rate.
104.
by mansr 14y ago
Probably referring to http://en.wikipedia.org/wiki/Internet_Watch_Foundation_and_W...
105.
by mansr 14y ago
Whenever pronunciation of a letter depends on the surrounding context, you have an exception.
106.
by mansr 14y ago
Nothing can stop someone simply saving the image and sending it as regular email. If it can be read, it can be copied. No point pretending otherwise. [Edit: fix stray question mark.]
107.
by mansr 14y ago
Another exception is 시 being pronounced [shi].
108.
by mansr 14y ago
The kernel shipped with Ubuntu has hundreds of patches. They simply don't bother sending them upstream. Whether this is because they don't care, because they know they are poor quality and would be rejected, or because they want to "differe
109.
by mansr 15y ago
Blamed by the compiler vendor. Most of these bugs were fixed when the vendor updated to a newer EDG version. Different compilers use different EDG versions, so a bug in one might not be present in another.
110.
by mansr 15y ago
The operand constraint should be "r" since bswap works only on registers. You can also simplify it a little using an input/output operand: asm ("bswap %0" : "+r"(x)); That said, since version 4.5, gcc recognises the typical byte-s
111.
by mansr 15y ago
On most x86 and ARM CPUs, byte-reversing a register is a single-cycle operation. PowerPC has byte-reversing load and store instructions but lacks an instruction to reverse a register.
112.
by mansr 15y ago
ARM supports unaligned memory accesses since v6. In most modern implementations, unaligned accesses falling entirely within a 16-byte aligned block have no penalty at all, while crossing 16-byte boundaries does impose a cost. If the locati
113.
by mansr 15y ago
About half the bugs I find in commercial compilers get blamed on the EDG frontend.
114.
by mansr 15y ago
Csmith is a random C program generator, which is useful for finding unknown compiler bugs. Creduce is a test case minimiser for reducing a large C file found to trigger some bug to a minimal test case. The input can be either real-world c
115.
by mansr 15y ago
That's not "missed optimisation," that's "generating ridiculous code."
116.
by mansr 15y ago
One way of actively looking for compiler bugs is using a tool like Csmith[1]. Another is to compile some known-difficult code (e.g. Libav[2]) with various combinations of (optimisation) flags until the test suite fails. Most of the bugs I
117.
by mansr 15y ago
I have been the first to trigger two CPU bugs and came across a third a few days after it was discovered, before it was published. Once errata are published, software workarounds are usually put in place quickly, and tripping over them is
118.
by mansr 15y ago
I also found the gorilla game and had much more fun adding various "improvements" than actually playing it.
119.
by mansr 15y ago
I learned from my father, by looking at code, and by reading books/manuals.
120.
by mansr 15y ago
If the number of possible messages is greater than the number of possible hashes, collisions are trivially guaranteed to occur. Since hashes are typically used with messages longer than 192 bits, SHA-1 collisions are certainly a possibilit

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