Selective encoding of data values for memory cell blocks
View Patent ↗An integrated circuit device can include a plurality of configuration storage locations each comprising at least one encoding field. Each encoding field can selectively enable at least one received data value to be encoded into an encoded data value prior to being applied to a corresponding block of the integrated circuit device. Each block can comprise a plurality of content addressable memory (CAM) cells.
1. An integrated circuit device, comprising:
a plurality of configuration storage locations each comprising at least one encoding field that selectively enables at least one received data value to be encoded into an encoded data value prior to being applied to a corresponding block of the integrated circuit device, and a logical table field that provides a logical table identification value for the corresponding block; and
each block comprising a plurality of content addressable memory (CAM) cells and being enabled in a search operation based upon at least the logical table identification value corresponding to the block.
2. The integrated circuit device of claim 1 , wherein:
the at least one received data value comprises a compare data value that is compared to data values stored in locations of at least one block.
3. The integrated circuit device of claim 2 , wherein:
the compare data value is encoded according to at least a “one hot” encoding in which each possible combination of N compare data bit values is encoded into different 2 N -bit applied compare data values, where each 2 N -bit applied compare data value has only one bit that differs from the other bits of the same value, and where N>1.
4. The integrated circuit device of claim 1 , wherein:
the at least one received data value comprises at least a stored data value that is stored within the block and compared with compare data values in a search operation.
5. The integrated circuit device of claim 4 , wherein:
the stored data value is encoded according to at least a “one hot” encoding in which each possible combination of N compare data bit values is encoded into different 2 N -bit encoded stored data values, where each 2 N -bit encoded stored data value has only one bit that differs from the other bits of the same value, and where N>1.
6. The integrated circuit device of claim 4 , wherein:
the at least one received data value comprises a combination of a stored data value and corresponding mask value.
7. The integrated circuit device of claim 1 , wherein:
the at least one received data value comprises an address value.
8. The integrated circuit of claim 7 , wherein:
the address value is encoded to activate multiple word lines in response to the address value.
9. The integrated circuit of claim 1 , further including:
a data bus; and
each block further comprises an encoding circuit coupled between the data bus and the corresponding plurality of CAM cells, each encoding circuit selectively providing at least one encoding function based on a corresponding encoding field.
10. The integrated circuit of claim 1 , wherein:
each encoding field further selectively enables at least one data value output from the corresponding block to be decoded from a stored encoded data value into an unencoded read data value.
11. The integrated circuit of claim 10 , further including:
a data bus; and
each block further comprises a decoding circuit coupled between the data bus and the corresponding plurality of CAM cells, each decoding circuit providing one of a plurality of decoding functions based on the corresponding encoding type field.
12. The integrated circuit of claim 10 , further including:
a data bus; and
a global decoding circuit coupled between the data bus and a plurality of blocks, the global decoding circuit providing one of a plurality of decoding functions based on a selected encoding field.
13. The integrated circuit of claim 12 , further including:
a block decoder that generates a block identification value according to a received address value, the block identification value accessing the encoding field of the corresponding block.
14. The integrated circuit device of claim 1 , wherein:
a logical table register having a plurality of locations that store search table identification values; and
each block is enabled in a search operation based upon a comparison between a search table identification value accessed from the logical table register and the logical table identification value corresponding to the block.
15. A method of applying data values to blocks of a memory device, each block comprising content addressable memory (CAM) cells, comprising the steps of:
providing a separate configuration value and logical table value for each block;
receiving a data value for application to at least one block of the memory device;
if the configuration value for the block indicates an encoding operation, encoding the data value prior to applying it to the block;
if the configuration value for the block does not indicate an encoding operation, applying the data value to the block without encoding the data value; and
enabling access to each block based on the logical table value of the block.
16. The method of claim 15 , wherein:
the step of receiving a data value includes receiving a compare data value for comparison with stored data values stored in the at least one block; and
encoding the data value prior to applying it to the block includes encoding the compare data value into an applied compare data value that consumes less power when driving compare data lines than a corresponding applied compare data value without encoding.
17. The method of claim 15 , further including:
the step of receiving a data value includes receiving a write data value for storage in the at least one block.
18. The method of claim 15 , further including:
accessing a stored data value stored in the at least one block of the memory device;
if a configuration value for the block indicates an encoding operation, decoding the stored data value prior to outputting it from the memory device;
if the configuration value for the block does not indicate an encoding operation, outputting the stored data value from the device without decoding the stored data value.
19. An integrated circuit device, comprising:
storing means for storing configuration values and logical table values for each of a plurality of content addressable memory (CAM) blocks; and
encoding means for selectively encoding data values prior to applying such data values to a CAM block according to the configuration value for the CAM block; and
access means for selectively accessing each CAM block based on the logical table value for the CAM block.
20. The method of claim 19 , wherein:
the encoding means encodes of N bits of a received compared data value into 2 N -bit applied compare data values, where each 2 N -bit applied compare data value has only one bit that differs from the other bits of the same value, and where N>1.
21. The method of claim 19 , wherein:
the encoding means encodes write data values.