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In computer science CDR coding is a compressed data representation for Lisp linked lists. It was developed and patented by the MIT Artificial Intelligence Laboratory, and implemented in computer hardware in a number of Lisp machines derived from the MIT CADR.
CDR coding is in fact a fairly general idea; whenever a data object A ends in a reference to another data structure B, we can instead place the structure B itself there, overlapping and running off the end of A. By doing this we free the space required by the reference, which can add up if done many times, and also improve locality of reference, enhancing performance on modern machines. The transformation is especially effective for the cons-based lists it was created for; we free about half of the space for each node we perform this transformation on.
It is not always possible to perform this substitution, because there might not be a large enough chunk of free space beyond the end of A. Thus, some objects will end in a real reference, and some with the referenced object, and the machine must be able to tell by reading the final cell which one it is. This can be accomplished with some inefficiency in software by the use of tagged pointers, which allow a pointer in a final position to be specifically tagged as such, but is best done in hardware.
In the presence of mutable objects, CDR coding becomes more complex. If a reference is updated to point to another object, but currently has an object stored in that field, the object must be relocated, along with any other pointers to it. Not only are such moves typically expensive or impossible, but over time they cause fragmentation of the store. This problem is typically avoided by using CDR coding only on immutable data structures.
In computer science CDRcoding is a compressed data representation for Lisp linked lists. It was developed and patented by the MIT Artificial Intelligence...
characters. CAR and CDR, in the programming language Lisp CDRcoding, in the programming language Lisp CDR (file format), native to CorelDRAW .cdr, the file extension...
In computer programming, CAR (car) /kɑːr/ and CDR (cdr) (/ˈkʌdər/ or /ˈkʊdər/ ) are primitive operations on cons cells (or "non-atomic S-expressions")...
a humanized antibody can be accomplished by inserting the appropriate CDRcoding segments (so-called 'donor', responsible for the desired binding properties)...
case, operation time still increases linearly with the size of the list. CDRcoding Skip list T-tree XOR linked list Hashed array tree Shao, Z.; Reppy, J...
a tagged architecture, and the remaining bits were used to implement CDRcoding (wherein the usual linked list elements are compressed to occupy roughly...
Lieutenant Commander (also hyphenated lieutenant-commander and abbreviated Lt Cdr, LtCdr., LCDR, or LCdr) is a commissioned officer rank in many navies. The rank...
increasing cache performance while decreasing memory overhead for references. CDRcoding does both these as well, by replacing references with the actual data...
evaluation, class hierarchy (see below), arbitrary-precision arithmetic, CDRcoding, the indirection bit, and other kinds of tagged pointers, are usually...
version X4 (14) on, the CDR file is a ZIP-compressed directory of several files, among them XML files and the RIFF-structured riffdata.cdr with the familiar...
Wing commander (Wg Cdr or W/C) is a senior officer rank used by some air forces, with origins from the Royal Air Force. The rank is used by air forces...
This is a list of all airline codes. The table lists the IATA airline designators, the ICAO airline designators and the airline call signs (telephony...
contents of the address part of register), and a right half, referred to as the cdr (the second element, or contents of the decrement part of register). It is...
specify only the wrapper but not the coding, a number of file formats specify both a storage layer and the coding, as part of modular design and forward...
A regional lockout (or region coding) is a class of digital rights management preventing the use of a certain product or service, such as multimedia or...
contained in a Central Data Repository (CDR). This CDR contains information from AHLTA, CHCS, and AHLTA-Theater. The AHLTA CDR is a comprehensive full scale world-wide...
Each Ivory instruction was 18 bits wide and two instructions plus a 2-bit CDRcode and 2-bit Data Type were in each instruction word fetched from memory....
"Casus Belli", Nathan James is under the command of CDR Kara Green and her executive officer is CDR Carlton Burk. In the series finale, "Commitment", Nathan...
algorithms are based on modified discrete cosine transform (MDCT) coding and linear predictive coding (LPC). In hardware, audio codec refers to a single device...
"Coincidence much? Irrfan Khan's Blackmail to have a connect with the ongoing CDR row, details inside". dna. 28 March 2018. Retrieved 23 September 2018. "Irrfan...
injudiciously in code. The nconc procedure (called append! in Scheme) performs the same function as append, but destructively: it alters the cdr of each argument...
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