Entry location in a content addressable memory
View Patent ↗A method for performing a search in a content addressable memory (“CAM”) device comprising comparing a search key with compound entries in a CAM array, wherein at least one of the compound entries includes (i) a ternary CAM word having a data word and a mask word, and (ii) a mask specifier that indicates the state of the mask word, and wherein the search key includes (i) a search word component, and (ii) a search mask component, and wherein the ternary CAM word is compared with the search word and the mask specifier is compared with the search word component; and generating a match signal associated with an compound entry that matches the search key.
1. A method for performing a search in a content addressable memory (“CAM”) device, the method comprising:
comparing a search key with compound entries in a CAM array, wherein at least one of the compound entries includes (i) a ternary CAM word having a data word and a mask word, and (ii) a mask specifier that indicates the state of the mask word, and wherein the search key includes (i) a search word component, and (ii) a search mask component, and wherein the ternary CAM word is compared with the search word component and the mask specifier is compared with the search word component; and
generating a match signal associated with a compound entry that matches the search key.
2. The method of claim 1 , further comprising generating an address in the CAM array for the compound entry that matches the search key.
3. The method of claim 1 , further comprising deleting the compound entry that matches the search key.
4. The method of claim 1 , further comprising relocating the compound entry that matches the search key to another location in the CAM array.
5. A method for locating an entry in an array of ternary content addressable memory (“CAM”) cells, the method comprising:
determining that a first group of bits of a search key match a first group of bits of the entry of the CAM array, the first group of bits of the entry having an associated group of local mask bits; and
concurrently determining that a second group of bits of the search key match a second group of bits in the entry of the CAM array, wherein the second group of bits of the entry comprises a representation of the local mask bits.
6. The method of claim 5 , wherein the second group of bits of the entry comprise the local mask bits.
7. The method of claim 5 , wherein the second group of bits of the entry comprise an encoding of the local mask bits.
8. The method of claim 5 , further comprising generating a match signal associated with the entry.
9. The method of claim 5 , further comprising generating an address for the entry.
10. The method of claim 5 , further comprising deleting the entry.
11. The method of claim 5 , further comprising relocating the entry in the ternary CAM array.
12. A method for locating an entry in an array of ternary content addressable memory (“CAM”) cells, the method comprising:
performing a ternary compare operation between a first field of a search key and a ternary CAM word portion of the entry in the ternary CAM array, wherein the ternary CAM word portion of the entry includes a data word and a local mask word; and
performing an unmasked compare operation between a second field of the search key and a mask specifier of the entry in the ternary CAM array, wherein the mask specifier comprises a representation of the local mask word.
13. The method of claim 12 , wherein the mask specifier comprises the local mask word.
14. The method of claim 12 , wherein the mask specifier comprises an encoding of the local mask word.
15. The method of claim 12 , further comprising generating a match signal associated with the entry.
16. The method of claim 12 , further comprising generating an address for the entry.
17. The method of claim 12 , further comprising deleting the entry.
18. The method of claim 12 , further comprising relocating the entry in the ternary CAM array.