:fence: n. 1. A sequence of one or more distinguished
({out-of-band}) characters (or other data items), used to
delimit a piece of data intended to be treated as a unit (the
computer-science literature calls this a `sentinel'). The NUL
(ASCII 0000000) character that terminates strings in C is a fence.
Hex FF is also (though slightly less frequently) used this way.
See {zigamorph}. 2. An extra data value inserted in an array or
other data structure in order to allow some normal test on the
array's contents also to function as a termination test. For
example, a highly optimized routine for finding a value in an array
might artificially place a copy of the value to be searched for
after the last slot of the array, thus allowing the main search
loop to search for the value without having to check at each pass
whether the end of the array had been reached. 3. [among users of
optimizing compilers] Any technique, usually exploiting knowledge
about the compiler, that blocks certain optimizations. Used when
explicit mechanisms are not available or are overkill. Typically a
hack: "I call a dummy procedure there to force a flush of the
optimizer's register-coloring info" can be expressed by the
shorter "That's a fence procedure".
-- The AI Hackers Dictionary
({out-of-band}) characters (or other data items), used to
delimit a piece of data intended to be treated as a unit (the
computer-science literature calls this a `sentinel'). The NUL
(ASCII 0000000) character that terminates strings in C is a fence.
Hex FF is also (though slightly less frequently) used this way.
See {zigamorph}. 2. An extra data value inserted in an array or
other data structure in order to allow some normal test on the
array's contents also to function as a termination test. For
example, a highly optimized routine for finding a value in an array
might artificially place a copy of the value to be searched for
after the last slot of the array, thus allowing the main search
loop to search for the value without having to check at each pass
whether the end of the array had been reached. 3. [among users of
optimizing compilers] Any technique, usually exploiting knowledge
about the compiler, that blocks certain optimizations. Used when
explicit mechanisms are not available or are overkill. Typically a
hack: "I call a dummy procedure there to force a flush of the
optimizer's register-coloring info" can be expressed by the
shorter "That's a fence procedure".
-- The AI Hackers Dictionary
Related:
- fence n. 1.
A sequence of one or more distinguished
(out-of-band) characters (or other data items)
used to delimit a piece of data intended to be treated as a unit (the computer-science literature calls this a `sentinel').... - vaxocentrism /vak`soh-sen'trizm/ n.
[analogy with
`ethnocentrism'] A notional disease said to afflict C programmers
who persist in coding according to certain assumptions that are
valid (esp.
under Unix) on VAXen but false elsewhere. Among these are... - EOF: /E-O-F/ [abbreviation, `End Of File'] n. 1. [techspeak] The
{out-of-band} value returned by C's sequential character-input
functions (and their equivalents in other environments) when end of
file has been reached.
This value is -1 under C libraries postdating V6 UNIX, but was originally 0.... - EOF /E-O-F/ n.
[abbreviation, `End Of File']
1.
[techspeak] The out-of-band value returned by C's sequential character-input functions (and their equivalents in other environments) when end of file has been reached.... - mash the stack: [C programming] n. To corrupt the execution stack
by writing past the end of a local array or other data structure.
Code that smashes the stack can cause a return from the routine to jump to a random address, resulting in some of the most insidious data-dependent bugs known to mankind.... - buzz: vi. 1. Of a program, to run with no indication of progress
and perhaps without guarantee of ever finishing
esp. said of programs thought to be executing tight loops of code.... - out-of-band: [from telecommunications and network theory] adj.
1. In software, describes values of a function which are not in its `natural' range of return values, but are rather signals that some kind of exception has occurred.... - live data: n. 1. Data that is written to be interpreted and takes
over program flow when triggered by some un-obvious operation, such
as viewing it.
One use of such hacks is to break security. For example, some smart terminals have commands that allow one to download strings to program key... - mash the stack n.
[C programming] To corrupt the execution
stack by writing past the end of a local array or other data
structure.
Code that smashes the stack can cause a return from the routine to jump to a random address, resulting in some of the most insidious data-dependent bugs known to mankind....
