Line data    Source code

       1             : // Copyright (c) 2021 The Bitcoin Core developers
       2             : // Distributed under the MIT software license, see the accompanying
       3             : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       4             : 
       5             : #include <util/serfloat.h>
       6             : 
       7             : #include <cmath>
       8             : #include <limits>
       9             : 
      10    43534555 : double DecodeDouble(uint64_t v) noexcept {
      11             :     static constexpr double NANVAL = std::numeric_limits<double>::quiet_NaN();
      12             :     static constexpr double INFVAL = std::numeric_limits<double>::infinity();
      13    43534555 :     double sign = 1.0;
      14    43534555 :     if (v & 0x8000000000000000) {
      15      255890 :         sign = -1.0;
      16      255890 :         v ^= 0x8000000000000000;
      17      255890 :     }
      18             :     // Zero
      19    43534555 :     if (v == 0) return copysign(0.0, sign);
      20             :     // Infinity
      21      857406 :     if (v == 0x7ff0000000000000) return copysign(INFVAL, sign);
      22             :     // Other numbers
      23      857404 :     int exp = (v & 0x7FF0000000000000) >> 52;
      24      857404 :     uint64_t man = v & 0xFFFFFFFFFFFFF;
      25      857404 :     if (exp == 2047) {
      26             :         // NaN
      27         268 :         return NANVAL;
      28      857136 :     } else if (exp == 0) {
      29             :         // Subnormal
      30         268 :         return copysign(ldexp((double)man, -1074), sign);
      31             :     } else {
      32             :         // Normal
      33      856868 :         return copysign(ldexp((double)(man + 0x10000000000000), -1075 + exp), sign);
      34             :     }
      35    43534555 : }
      36             : 
      37    91558927 : uint64_t EncodeDouble(double f) noexcept {
      38    91558927 :     int cls = std::fpclassify(f);
      39    91558927 :     uint64_t sign = 0;
      40    91558927 :     if (copysign(1.0, f) == -1.0) {
      41      511915 :         f = -f;
      42      511915 :         sign = 0x8000000000000000;
      43      511915 :     }
      44             :     // Zero
      45    91558927 :     if (cls == FP_ZERO) return sign;
      46             :     // Infinity
      47     1792175 :     if (cls == FP_INFINITE) return sign | 0x7ff0000000000000;
      48             :     // NaN
      49     1792171 :     if (cls == FP_NAN) return 0x7ff8000000000000;
      50             :     // Other numbers
      51             :     int exp;
      52     1791903 :     uint64_t man = std::round(std::frexp(f, &exp) * 9007199254740992.0);
      53     1791903 :     if (exp < -1021) {
      54             :         // Too small to represent, encode 0
      55         536 :         if (exp < -1084) return sign;
      56             :         // Subnormal numbers
      57         536 :         return sign | (man >> (-1021 - exp));
      58             :     } else {
      59             :         // Too big to represent, encode infinity
      60     1791367 :         if (exp > 1024) return sign | 0x7ff0000000000000;
      61             :         // Normal numbers
      62     1791367 :         return sign | (((uint64_t)(1022 + exp)) << 52) | (man & 0xFFFFFFFFFFFFF);
      63             :     }
      64    91558927 : }