Bitcoin Core  27.99.0
P2P Digital Currency
assumptions.h
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1 // Copyright (c) 2009-2010 Satoshi Nakamoto
2 // Copyright (c) 2009-2021 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