The Turbo Coprocessor2 Decoder allows us to decode turbo codes 1/2, 1/3, 1/4 and 1/5. Whereas, from the Turbo Coprocessor 3's datasheet, it seems as if only code rate 1/3 can be decoded ( and higher rates possibly by puncturing). However, there seems to be no mechanism in place to handle lower coderates like 1/4 and 1/5.
Am I making the right conclusions? Is there a way to decode coderates lower than 1/3rd using TCP3d?
Also, in both the version of TCP, the constraint lengths and code coefficients seem to be non-configurable. Any technique to encode and decode custom made turbo codes?