text: #ifndef SPX_UTILS_H
  #define SPX_UTILS_H
  
  #include "params.h"
  #include <stddef.h>
  #include <stdint.h>
  
  /**
   * Converts the value of 'in' to 'outlen' bytes in big-endian byte order.
   */
  void PQCLEAN_SPHINCSSHA256128FSIMPLE_CLEAN_ull_to_bytes(
      unsigned char *out, size_t outlen, unsigned long long in);
  
  /**
   * Converts the inlen bytes in 'in' from big-endian byte order to an integer.
   */
  unsigned long long PQCLEAN_SPHINCSSHA256128FSIMPLE_CLEAN_bytes_to_ull(
      const unsigned char *in, size_t inlen);
  
  /**
   * Computes a root node given a leaf and an auth path.
   * Expects address to be complete other than the tree_height and tree_index.
   */
  void PQCLEAN_SPHINCSSHA256128FSIMPLE_CLEAN_compute_root(
      unsigned char *root, const unsigned char *leaf,
      uint32_t leaf_idx, uint32_t idx_offset,
      const unsigned char *auth_path, uint32_t tree_height,
      const unsigned char *pub_seed, uint32_t addr[8]);
  
  /**
   * For a given leaf index, computes the authentication path and the resulting
   * root node using Merkle's TreeHash algorithm.
   * Expects the layer and tree parts of the tree_addr to be set, as well as the
   * tree type (i.e. SPX_ADDR_TYPE_HASHTREE or SPX_ADDR_TYPE_FORSTREE).
   * Applies the offset idx_offset to indices before building addresses, so that
   * it is possible to continue counting indices across trees.
   */
  void PQCLEAN_SPHINCSSHA256128FSIMPLE_CLEAN_treehash_FORS_HEIGHT(
      unsigned char *root, unsigned char *auth_path,
      const unsigned char *sk_seed, const unsigned char *pub_seed,
      uint32_t leaf_idx, uint32_t idx_offset,
      void (*gen_leaf)(
          unsigned char * /* leaf */,
          const unsigned char * /* sk_seed */,
          const unsigned char * /* pub_seed */,
          uint32_t /* addr_idx */, const uint32_t[8] /* tree_addr */),
      uint32_t tree_addr[8]);
  
  void PQCLEAN_SPHINCSSHA256128FSIMPLE_CLEAN_treehash_TREE_HEIGHT(
      unsigned char *root, unsigned char *auth_path,
      const unsigned char *sk_seed, const unsigned char *pub_seed,
      uint32_t leaf_idx, uint32_t idx_offset,
      void (*gen_leaf)(
          unsigned char * /* leaf */,
          const unsigned char * /* sk_seed */,
          const unsigned char * /* pub_seed */,
          uint32_t /* addr_idx */, const uint32_t[8] /* tree_addr */),
      uint32_t tree_addr[8]);
  
  #endif
  