Search results
Results from the WOW.Com Content Network
In the C programming language, Duff's device is a way of manually implementing loop unrolling by interleaving two syntactic constructs of C: the do-while loop and a switch statement. Its discovery is credited to Tom Duff in November 1983, when Duff was working for Lucasfilm and used it to speed up a real-time animation program.
On modern processors, loop unrolling is often counterproductive, as the increased code size can cause more cache misses; cf. Duff's device. [1] The goal of loop unwinding is to increase a program's speed by reducing or eliminating instructions that control the loop, such as pointer arithmetic and "end of loop" tests on each iteration; [2 ...
A loop-switch sequence [1] (also known as the for-case paradigm [2] or Anti-Duff's Device) is a programming antipattern where a clear set of steps is implemented as a switch-within-a-loop. The loop-switch sequence is a specific derivative of spaghetti code .
Simon Tatham's contribution, [38] based on Duff's device, is a notable example of the genre, and is the basis for Protothreads and similar implementations. [39] In addition to Duff's objections, [ 24 ] Tatham's own comments provide a frank evaluation of the limitations of this approach: "As far as I know, this is the worst piece of C hackery ...
A protothread is a low-overhead mechanism for concurrent programming.. Protothreads function as stackless, lightweight threads, or coroutines, providing a blocking context cheaply using minimal memory per protothread (on the order of single bytes).
An event can be user interaction, network traffic, system processing, timer activity, inter-process communication, among others. For non-interactive, I/O only events, Windows has I/O completion ports. I/O completion port loops run separately from the Message loop, and do not interact with the Message loop out of the box.
Unidirectional Link Detection (UDLD) is one of two major features (UDLD and loop guard) in Cisco Switches to prevent Layer 2 loops. Spanning-Tree Protocol (STP) resolves redundant physical topology into a loop-free, tree-like forwarding topology via blocking one or more ports.
Iterative deepening prevents this loop and will reach the following nodes on the following depths, assuming it proceeds left-to-right as above: 0: A; 1: A, B, C, E (Iterative deepening has now seen C, when a conventional depth-first search did not.) 2: A, B, D, F, C, G, E, F (It still sees C, but that it came later.