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公开(公告)号：US5978822A
公开(公告)日：1999-11-02
申请号：US581047
申请日：1995-12-29
摘要： A circuit having a single branch, which is controllable to implement either a left or right shift of bits of a data word. Preferably, the circuit is controllable to implement any selected one of the following operations: a left or right shift of bits of the word; and rotation (to the left or right) of bits of the word. In a preferred implementation, the circuit includes a set of multiplexer stages and circuitry for selectively inverting the order of the bits of the word input to, and the word output from, the set of multiplexer stages. Each of the multiplexer stages shifts the bits of the word it receives either by zero bits (in response to a first control signal), or by a positive number of bits (in response to a second control signal). By selectively controlling various subsets of the multiplexer stages, the bits of the input word can be shifted by any of a number of places (from zero to N, where N is some positive number). In another aspect, the invention is a circuit for rotating bits of an input word (by two or more bits to the left or right) during a single cycle, by duplicating the input word to form an extended word, shifting bits of the extended word, and selecting a subset of the shifted bits of the extended word. Other aspects of the invention are methods performed by, and a digital signal processor including, either embodiment of the inventive circuit.
摘要翻译： 具有单个分支的电路，其可控制以实现数据字的位的左移或右移。 优选地，电路是可控制的，以实现以下操作中的任何选择的一个：字的位的左移或右移; 以及字的位的旋转（向左或向右）。 在优选的实施方案中，电路包括一组多路复用器级和电路，用于选择性地反转字输入的位的顺序和多路复用器级的集合输出的字。 多路复用器级中的每一个通过零位（响应于第一控制信号）或通过正数位（响应于第二控制信号）来移位其接收的字的位。 通过选择性地控制多路复用器级的各个子集，可以通过多个位置（从零到N，其中N是一些正数）中的任意一个来移位输入字的位。 另一方面，本发明是一种电路，用于在单个周期期间通过复制输入字以形成扩展字来转换输入字的位（向左或向右两位或更多位），从而使扩展字的位移位 ，并且选择扩展字的移位位的子集。 本发明的其他方面是由本发明的电路的任一实施例执行的方法和数字信号处理器。
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