text: /* Based on the public domain implementation in
   * crypto_hash/sha512/ref/ from http://bench.cr.yp.to/supercop.html
   * by D. J. Bernstein */
  
  #include <stddef.h>
  #include <stdint.h>
  #include <string.h>
  
  #include "sha2.h"
  #include "sha256.h"
  #include "utils.h"
  
  /*
   * Compresses an address to a 22-byte sequence.
   * This reduces the number of required SHA256 compression calls, as the last
   * block of input is padded with at least 65 bits.
   */
  void PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_compress_address(unsigned char *out, const uint32_t addr[8]) {
      PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_ull_to_bytes(out,      1, addr[0]); /* drop 3 bytes of the layer field */
      PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_ull_to_bytes(out + 1,  4, addr[2]); /* drop the highest tree address word */
      PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_ull_to_bytes(out + 5,  4, addr[3]);
      PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_ull_to_bytes(out + 9,  1, addr[4]); /* drop 3 bytes of the type field */
      PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_ull_to_bytes(out + 10, 4, addr[5]);
      PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_ull_to_bytes(out + 14, 4, addr[6]);
      PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_ull_to_bytes(out + 18, 4, addr[7]);
  }
  
  /**
   * Requires 'input_plus_four_bytes' to have 'inlen' + 4 bytes, so that the last
   * four bytes can be used for the counter. Typically 'input' is merely a seed.
   * Outputs outlen number of bytes
   */
  void PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_mgf1(
      unsigned char *out, unsigned long outlen,
      unsigned char *input_plus_four_bytes, unsigned long inlen) {
      unsigned char outbuf[PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_SHA256_OUTPUT_BYTES];
      unsigned long i;
  
      /* While we can fit in at least another full block of SHA256 output.. */
      for (i = 0; (i + 1)*PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_SHA256_OUTPUT_BYTES <= outlen; i++) {
          PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_ull_to_bytes(input_plus_four_bytes + inlen, 4, i);
          sha256(out, input_plus_four_bytes, inlen + 4);
          out += PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_SHA256_OUTPUT_BYTES;
      }
      /* Until we cannot anymore, and we fill the remainder. */
      if (outlen > i * PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_SHA256_OUTPUT_BYTES) {
          PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_ull_to_bytes(input_plus_four_bytes + inlen, 4, i);
          sha256(outbuf, input_plus_four_bytes, inlen + 4);
          memcpy(out, outbuf, outlen - i * PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_SHA256_OUTPUT_BYTES);
      }
  }
  
  
  /**
   * Absorb the constant pub_seed using one round of the compression function
   * This initializes hash_state_seeded, which can then be reused in thash
   **/
  void PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_seed_state(sha256ctx *hash_state_seeded, const unsigned char *pub_seed) {
      uint8_t block[PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_SHA256_BLOCK_BYTES];
      size_t i;
  
      for (i = 0; i < PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_N; ++i) {
          block[i] = pub_seed[i];
      }
      for (i = PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_N; i < PQCLEAN_SPHINCSSHA256128FROBUST_CLEAN_SHA256_BLOCK_BYTES; ++i) {
          block[i] = 0;
      }
  
      sha256_inc_init(hash_state_seeded);
      sha256_inc_blocks(hash_state_seeded, block, 1);
  }
  