ROHD-HCL implements Hamming codes for error correction and detection. The Wikipedia article does a good job explaining the background and functionality of Hamming codes, for those unfamiliar.
An error correcting code is a code that can be included in a transmission with some data that enables the receiver to check whether there was an error (up to some number of bit flips), and possibly correct the error (up to a limit). There is a trade-off where increasing the number of additional bits included in the code improves error checking/correction, but costs more bits (area/power/storage).
ROHD-HCL only has Hamming codes currently, but there are many types of error correcting codes. The HammingEccTransmitter and HammingEccReceiver can support any data width, and support the following configurations:
| Type | Errors detectable | Errors correctable | Extra parity bit |
|---|---|---|---|
| Single Error Correction (SEC) | 1 | 1 | No |
| Double Error Detection (SEDDED) | 2 | 0 | No |
| Single Error Correction, Double Error Detection (SECDED) | 2 | 1 | Yes |
| Triple Error Detection (SEDDEDTED) | 3 | 0 | Yes |