debug_float.hpp

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// SPDX-FileCopyrightText: 2026 Jarosław Pelczar <jarek@jpelczar.com>
//
// SPDX-License-Identifier: BSD-2-Clause
 
#pragma once
 
#include <cstddef>
#include <cstdio>
#include <microfmt/microfmt.hpp>
#include <type_traits>
 
namespace reloco {
 
namespace detail {
 
// low-level formatting: raw character pointers and integer width conversions bounded by the buffer sizes checked here.
RELOCO_BEGIN_UNSAFE_CODE
template <typename T> inline void format_debug_float(T val, const sink &out) noexcept {
  char buf[64] = {};
  int written = {};
  if constexpr (std::is_same_v<T, long double>) {
    written = std::snprintf(buf, sizeof(buf), "%Lg", val);
  } else {
    written = std::snprintf(buf, sizeof(buf), "%g", static_cast<double>(val));
  }
  if (written <= 0) {
    return;
  }
 
  const std::size_t len =
      static_cast<std::size_t>(written) < sizeof(buf) ? static_cast<std::size_t>(written) : sizeof(buf) - 1;
  const microfmt::string_view text(buf, len);
  out.write(text);
 
  const bool has_dot_or_exp = text.find('.') != microfmt::string_view::npos ||
                              text.find('e') != microfmt::string_view::npos ||
                              text.find('E') != microfmt::string_view::npos;
  const bool is_special =
      text.find("inf") != microfmt::string_view::npos || text.find("nan") != microfmt::string_view::npos;
  if (!has_dot_or_exp && !is_special) {
    out.write(".0");
  }
}
RELOCO_END_UNSAFE_CODE
 
} // namespace detail
 
template <> struct Debug<float> {
  static void format(float val, const sink &out) noexcept { detail::format_debug_float(val, out); }
};
 
template <> struct Debug<double> {
  static void format(double val, const sink &out) noexcept { detail::format_debug_float(val, out); }
};
 
template <> struct Debug<long double> {
  static void format(long double val, const sink &out) noexcept { detail::format_debug_float(val, out); }
};
 
} // namespace reloco