公开(公告)号：US20030028713A1

公开(公告)日：2003-02-06

申请号：US10142855

申请日：2002-05-09

Applicant: Netlogic Microsystems, Inc.

Inventor： Sandeep Khanna ,  Bindiganavale S. Nataraj ,  Varadarajan Srinivasan

IPC: G06F012/00

CPC classification number: H04L61/00 ,  G11C15/04 ,  H04L29/12009

Abstract: A method and apparatus for determining an exact match in a ternary CAM device. Each ternary CAM cell includes CAM cells for storing CAM data, local mask cells for storing prefix mask data for the corresponding CAM cells, and a mask override circuit. Each local mask cell includes a masking circuit that masks the prefix mask data or CAM data provided to the comparison circuit, or masks the comparison result from the match line of a CAM cell. The mask override circuit effectively overrides the prefix mask data stored in the local mask cell. The mask override circuit performs the override function by negating the operation of the mask circuit such that no masking operation occurs when an exact match compare or invalidate function is performed by the ternary CAM device. For example, during an exact match operation, the CAM cells compare comparand data with unmasked CAM data and provide the compare results to CAM match lines. The local mask cells also compare mask data with the stored prefix mask data and provide the results to mask match lines. If both compares result in a match, then an exact match entry is located in the ternary CAM device. The locations or indexes of the exact match entries may then be output from the CAM device. One or more of the exact match locations may also be invalidated or deleted.

公开(公告)号：US20020129199A1

公开(公告)日：2002-09-12

申请号：US10025661

申请日：2001-12-18

Applicant: Netlogic Microsystems, Inc.

Inventor： Varadarajan Srinivasan ,  Bindiganavale S. Nataraj ,  Sandeep Khanna

IPC: G06F012/00

CPC classification number: G11C15/00

Abstract: A content address memory (CAM) device that implements a read next highest priority or nullRNHPMnull instruction. The CAM device initially searches its CAM locations for a match with comparand data. If multiple matches are identified, then the CAM device initially outputs the highest priority matching address. The CAM device may output the highest priority matching address in the same system or clock cycle in which the compare instruction was provided. The CAM device may also output data stored in one or more of the CAM cells located at the highest priority matching location and/or status information including the match flags, a full flag, validity bits (e.g., skip and empty bits), and other status information. An RNHPM instruction may then be provided to the CAM device in the next clock cycle or a later clock cycle and cause the next highest priority matching address to be output by the CAM device. The next highest priority matching address may be output in the same or subsequent cycle as the RNHPM instruction and may also cause the CAM device to output data stored in one or more of the CAM cells located at the next highest priority matching location and/or status information for that location. RNHPM instructions can continue to be supplied to the CAM device until no further matching locations are detected.

Abstract translation: 实现读取下一个最高优先级或“RNHPM”指令的内容地址存储器（CAM）设备。 CAM设备最初搜索其CAM位置以获得与比较数据的匹配。 如果识别出多个匹配，则CAM设备最初输出最高优先级匹配地址。 CAM设备可以在提供比较指令的相同系统或时钟周期中输出最高优先级的匹配地址。 CAM设备还可以输出存储在位于最高优先级匹配位置的一个或多个CAM单元中的数据和/或包括匹配标志的状态信息，完整标志，有效位（例如，跳过和空位）等的数据 状态信息。 然后可以在下一个时钟周期或更晚的时钟周期中向CAM设备提供RNHPM指令，并且使CAM设备输出下一个最高优先级的匹配地址。 可以在与RNHPM指令相同或随后的周期中输出下一个最高优先级的匹配地址，并且还可以使CAM设备输出存储在位于下一个最高优先级匹配位置和/或状态的一个或多个CAM单元中的数据 该位置的信息。 RNHPM指令可以继续提供给CAM设备，直到没有检测到更多的匹配位置为止。