Pre-computation based ternary content addressable memory
AssigneeBroadcom Corporation
InventorVinay Iyengar
Life of this patent
Estimating the term…
Abstract
A pre-computation based TCAM configured to reduce the number of match lines being pre-charged during a search operation to save power is disclosed. The pre-computation based TCAM stores additional information in a secondary TCAM that can be used to determine which match lines in a primary TCAM storing data words to be searched need not be pre-charged because they are associated with data words guaranteed to not match. The additional information stored in secondary TCAM can include a pre-computation word that represents a range inclusive of a lower and upper bound of a number of ones or zeroes possible in a corresponding data word stored in the primary TCAM.
Claims20
A pre-computation based ternary content addressable memory (TCAM), comprising:
- a counter configured to generate a count of a number of ones or zeros in a search word;
- a primary TCAM configured to store a data word;
- and
- a secondary TCAM configured to store a pre-computation word representing a range inclusive of a lower and upper bound of a number of ones or zeros possible in the data word, wherein the secondary TCAM is configured to disable pre-charging of a match line associated with the data word if the count of the number of ones or zeroes in the search word does not fall within the range represented by the pre-computation word.
A pre-computation based ternary content addressable memory (TCAM), comprising:
- a counter configured to generate a count of a number of ones or zeros in a search word;
- a primary TCAM configured to store a data word;
- and
- a secondary TCAM configured to store a pre-computation word representing a range inclusive of a lower and upper bound of a number of ones or zeros possible in a portion of the data word, wherein the secondary TCAM is configured to disable pre-charging of a match line associated with the data word if the count of the number of ones or zeroes in a portion of the search word does not fall within the range represented by the pre-computation word.
A method for performing pre-computation in a ternary content addressable memory (TCAM), the method comprising:
- generating a count of a number of ones or zeros in a search word;
- storing a data word in a primary TCAM;
- storing a pre-computation word representing a range inclusive of a lower and upper bound of a number of ones or zeros possible in the data word in a secondary TCAM;
- and
- disabling pre-charging of a match line associated with the data word if the count of the number of ones or zeroes in the search word does not fall within the range represented by the pre-computation word.
Dependencies are inferred from the claim text.