/*

* (C) 2016 Jack Lloyd

*

* Botan is released under the Simplified BSD License (see license.txt)

*/

#include <botan/rng.h>

#include <botan/entropy_src.h>

#include <botan/internal/loadstor.h>

#include <botan/internal/os_utils.h>

#if defined(BOTAN_HAS_SYSTEM_RNG)

   #include <botan/system_rng.h>

#endif

#include <array>

namespace Botan {

void RandomNumberGenerator::randomize_with_ts_input(std::span<uint8_t> output) {

   if(this->accepts_input()) {

      constexpr auto s_hd_clk = sizeof(decltype(OS::get_high_resolution_clock()));

      constexpr auto s_sys_ts = sizeof(decltype(OS::get_system_timestamp_ns()));

      constexpr auto s_pid = sizeof(decltype(OS::get_process_id()));

      std::array<uint8_t, s_hd_clk + s_sys_ts + s_pid> additional_input = {0};

      auto s_additional_input = std::span(additional_input.begin(), additional_input.end());

      store_le(OS::get_high_resolution_clock(), s_additional_input.data());

      s_additional_input = s_additional_input.subspan(s_hd_clk);

#if defined(BOTAN_HAS_SYSTEM_RNG)

      System_RNG system_rng;

      system_rng.randomize(s_additional_input);

#else

      store_le(OS::get_system_timestamp_ns(), s_additional_input.data());

      s_additional_input = s_additional_input.subspan(s_sys_ts);

      store_le(OS::get_process_id(), s_additional_input.data());

#endif

      this->fill_bytes_with_input(output, additional_input);

   } else {

      this->fill_bytes_with_input(output, {});

   }

}

size_t RandomNumberGenerator::reseed(Entropy_Sources& srcs, size_t poll_bits, std::chrono::milliseconds poll_timeout) {

   if(this->accepts_input()) {

      return srcs.poll(*this, poll_bits, poll_timeout);

   } else {

      return 0;

   }

}

void RandomNumberGenerator::reseed_from_rng(RandomNumberGenerator& rng, size_t poll_bits) {

   if(this->accepts_input()) {

      this->add_entropy(rng.random_vec(poll_bits / 8));

   }

}

}  // namespace Botan