公开(公告)号：US07111123B1

公开(公告)日：2006-09-19

申请号：US10202526

申请日：2002-07-24

Applicant: Janet Zou

Inventor： Janet Zou

IPC: G06F12/02

CPC classification number: G11C15/00

Abstract: A content addressable memory includes a priority encoder that is in communication with an array of the content addressable memory cells to receive match signals, and from the match signals generating an output index signal in accordance with a priority sequence of the match signals. The priority encoder has a plurality of input circuits to receive the match signals from the CAM array. A priority setting circuit receives a priority transformation signal indicating a priority index for modification of the priority sequence. An encoding circuit is in communication with the plurality of input circuits and the priority setting circuit for generating the output index signal in accordance with the priority sequence. The priority encoder circuit further includes an enabling circuit for receiving an enabling signal. The enabling circuit communicates the enabling signals to the encoding circuit, such that upon deactivation of the enabling signal, the encoding circuit generates the output signal in accordance with the priority sequence with no modification by the priority setting circuit. The priority index indicates a region of the content addressable memory exempted from effective comparison. This allows the CAM array to be searched for multiple matches of the comparand. The priority index thus is an index address of the content addressable memory determined with a previous search of the content addressable memory. The priority index is provided to the priority setting circuit through a word line decoder of the array of content addressable memory cells.

Abstract translation: 内容可寻址存储器包括与内容可寻址存储器单元的阵列通信以接收匹配信号的优先编码器，以及根据匹配信号的优先顺序产生输出索引信号的匹配信号。 优先编码器具有多个输入电路，以接收来自CAM阵列的匹配信号。 优先级设置电路接收指示优先级序列的优先级索引的优先级变换信号。 编码电路与多个输入电路和优先级设定电路通信，用于根据优先顺序产生输出索引信号。 优先编码器电路还包括用于接收使能信号的使能电路。 使能电路将使能信号传送到编码电路，使得在禁用使能信号时，编码电路根据优先顺序生成输出信号，而不通过优先级设置电路进行修改。 优先级索引表示内容可寻址存储器的区域被免除有效比较。 这样可以搜索CAM阵列的比较数据的多个匹配项。 因此，优先级索引是通过先前搜索内容可寻址存储器确定的内容可寻址存储器的索引地址。 通过内容可寻址存储单元阵列的字线解码器将优先级索引提供给优先级设置电路。