compat32.hpp

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// SPDX-FileCopyrightText: 2026 Jarosław Pelczar <jarek@jpelczar.com>
//
// SPDX-License-Identifier: BSD-2-Clause
 
#pragma once
 
#include "address_space.hpp"
#include <cstdint>
#include <type_traits>
 
namespace microfmt {
 
// ============================================================================
// 32-bit Compatibility Pointer Primitive
// ============================================================================
 
template <typename T> class alignas(uint32_t) compat32_ptr {
public:
  using element_type = T;
 
  constexpr compat32_ptr() noexcept : raw_addr_(0) {}
  explicit constexpr compat32_ptr(std::nullptr_t) noexcept : raw_addr_(0) {}
  constexpr explicit compat32_ptr(uint32_t addr) noexcept : raw_addr_(addr) {}
 
  [[nodiscard]] constexpr uint32_t raw_value() const noexcept { return raw_addr_; }
  [[nodiscard]] constexpr uintptr_t to_uintptr() const noexcept { return static_cast<uintptr_t>(raw_addr_); }
  [[nodiscard]] constexpr bool is_null() const noexcept { return raw_addr_ == 0; }
  [[nodiscard]] constexpr explicit operator bool() const noexcept { return raw_addr_ != 0; }
 
  constexpr bool operator==(const compat32_ptr &other) const noexcept { return raw_addr_ == other.raw_addr_; }
  constexpr bool operator!=(const compat32_ptr &other) const noexcept { return raw_addr_ != other.raw_addr_; }
  constexpr bool operator==(std::nullptr_t) const noexcept { return raw_addr_ == 0; }
  constexpr bool operator!=(std::nullptr_t) const noexcept { return raw_addr_ != 0; }
 
private:
  uint32_t raw_addr_{0};
};
 
static_assert(sizeof(compat32_ptr<void>) == 4, "compat32_ptr must be exactly 4 bytes");
static_assert(alignof(compat32_ptr<void>) == 4, "compat32_ptr must be 4-byte aligned");
 
// ============================================================================
// Formatter for compat32_ptr<T>
// ============================================================================
 
template <typename T> struct formatter<compat32_ptr<T>> {
  constexpr void parse(format_parse_context &) noexcept {}
 
  void format(const compat32_ptr<T> &ptr, const sink &out) const noexcept {
    if (ptr.is_null()) {
      out.write("(null)");
    } else {
      microfmt::format_to(out, "{:#010x}", ptr.raw_value());
    }
  }
};
 
// ============================================================================
// Helpers for remote views
// ============================================================================
 
template <size_t N>
[[nodiscard]] constexpr auto make_remote_string32(compat32_ptr<const char> ptr, address_space_ref space,
                                                  char (&scratch)[N], size_t max_limit = 4096) noexcept {
  return remote_string_view(ptr.to_uintptr(), space, scratch, max_limit);
}
 
template <typename T, size_t N>
[[nodiscard]] constexpr auto make_remote_ref32(compat32_ptr<T> ptr, address_space_ref space,
                                               std::byte (&scratch)[N]) noexcept {
  return remote_ref<T>(ptr.to_uintptr(), space, scratch);
}
 
} // namespace microfmt