decompression of secp256r1 public keys

[StefanHri]

Hi,

I want to use uECC_shared_secret() to derive a shared secret. I have only the x coordinate of the public key. I assume the function uECC_shared_secret() requires the uncompressed key holding both coordinates {x,y}. How to decompress the public key? I found the following function in uECC link, however, this function appears to not be part of tinycrypt.