Static ring::digest::SHA512_256

pub static SHA512_256: Algorithm = Algorithm{output_len: SHA512_256_OUTPUT_LEN,
          chaining_len: SHA512_OUTPUT_LEN,
          block_len: SHA512_BLOCK_LEN,
          len_len: SHA512_LEN_LEN,
          block_data_order: GFp_sha512_block_data_order,
          format_output: sha512_format_output,
          initial_state:
              [2463787394917988140, 11481187982095705282, 2563595384472711505,
               10824532655140301501, 10819967247969091555,
               13717434660681038226, 3098927326965381290,
               1060366662362279074],
          id: AlgorithmID::SHA512_256,}

SHA-512/256 as specified in FIPS 180-4.

This is not the same as just truncating the output of SHA-512, as SHA-512/256 has its own initial state distinct from SHA-512's initial state.