assumptions.h raw

   1  // Copyright (c) 2009-2010 Satoshi Nakamoto
   2  // Copyright (c) 2009-present The Bitcoin Core developers
   3  // Distributed under the MIT software license, see the accompanying
   4  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   5  
   6  // Compile-time verification of assumptions we make.
   7  
   8  #ifndef BITCOIN_COMPAT_ASSUMPTIONS_H
   9  #define BITCOIN_COMPAT_ASSUMPTIONS_H
  10  
  11  #include <cstddef>
  12  #include <limits>
  13  
  14  // Assumption: We assume the floating-point types to fulfill the requirements of
  15  //             IEC 559 (IEEE 754) standard.
  16  // Example(s): Floating-point division by zero in ConnectBlock, CreateTransaction
  17  //             and EstimateMedianVal.
  18  static_assert(std::numeric_limits<float>::is_iec559, "IEEE 754 float assumed");
  19  static_assert(std::numeric_limits<double>::is_iec559, "IEEE 754 double assumed");
  20  
  21  // Assumption: We assume eight bits per byte (obviously, but remember: don't
  22  //             trust -- verify!).
  23  // Example(s): Everywhere :-)
  24  static_assert(std::numeric_limits<unsigned char>::digits == 8, "8-bit byte assumed");
  25  
  26  // Assumption: We assume integer widths.
  27  // Example(s): GetSizeOfCompactSize and WriteCompactSize in the serialization
  28  //             code.
  29  static_assert(sizeof(short) == 2, "16-bit short assumed");
  30  static_assert(sizeof(int) == 4, "32-bit int assumed");
  31  static_assert(sizeof(unsigned) == 4, "32-bit unsigned assumed");
  32  
  33  // Assumption: We assume size_t to be 32-bit or 64-bit.
  34  // Example(s): size_t assumed to be at least 32-bit in ecdsa_signature_parse_der_lax(...).
  35  //             size_t assumed to be 32-bit or 64-bit in MallocUsage(...).
  36  static_assert(sizeof(size_t) == 4 || sizeof(size_t) == 8, "size_t assumed to be 32-bit or 64-bit");
  37  static_assert(sizeof(size_t) == sizeof(void*), "Sizes of size_t and void* assumed to be equal");
  38  
  39  // Some important things we are NOT assuming (non-exhaustive list):
  40  // * We are NOT assuming a specific value for std::endian::native.
  41  // * We are NOT assuming a specific value for std::locale("").name().
  42  // * We are NOT assuming a specific value for std::numeric_limits<char>::is_signed.
  43  
  44  #endif // BITCOIN_COMPAT_ASSUMPTIONS_H
  45