// Copyright 2018 Ulf Adams
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//
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// The contents of this file may be used under the terms of the Apache License,
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// Version 2.0.
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//
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// (See accompanying file LICENSE-Apache or copy at
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// http://www.apache.org/licenses/LICENSE-2.0)
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//
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// Alternatively, the contents of this file may be used under the terms of
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// the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE-Boost or copy at
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// https://www.boost.org/LICENSE_1_0.txt)
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//
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// Unless required by applicable law or agreed to in writing, this software
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// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied.
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/*
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This is a derivative work
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*/
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#ifndef BOOST_JSON_DETAIL_RYU_DETAIL_COMMON_HPP
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#define BOOST_JSON_DETAIL_RYU_DETAIL_COMMON_HPP
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#include <boost/json/detail/config.hpp>
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#include <string.h>
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BOOST_JSON_NS_BEGIN
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namespace detail {
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namespace ryu {
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namespace detail {
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constexpr int DOUBLE_MANTISSA_BITS = 52;
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constexpr int DOUBLE_EXPONENT_BITS = 11;
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constexpr int DOUBLE_BIAS = 1023;
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#if defined(_M_IX86) || defined(_M_ARM)
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#define BOOST_JSON_RYU_32_BIT_PLATFORM
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#endif
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inline uint32_t decimalLength9(const uint32_t v) {
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// Function precondition: v is not a 10-digit number.
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// (f2s: 9 digits are sufficient for round-tripping.)
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// (d2fixed: We print 9-digit blocks.)
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BOOST_ASSERT(v < 1000000000);
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if (v >= 100000000) { return 9; }
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if (v >= 10000000) { return 8; }
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if (v >= 1000000) { return 7; }
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if (v >= 100000) { return 6; }
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if (v >= 10000) { return 5; }
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if (v >= 1000) { return 4; }
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if (v >= 100) { return 3; }
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if (v >= 10) { return 2; }
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return 1;
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}
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// Returns e == 0 ? 1 : ceil(log_2(5^e)).
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inline int32_t pow5bits(const int32_t e) {
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// This approximation works up to the point that the multiplication overflows at e = 3529.
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// If the multiplication were done in 64 bits, it would fail at 5^4004 which is just greater
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// than 2^9297.
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BOOST_ASSERT(e >= 0);
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BOOST_ASSERT(e <= 3528);
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return (int32_t) (((((uint32_t) e) * 1217359) >> 19) + 1);
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}
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// Returns floor(log_10(2^e)).
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inline uint32_t log10Pow2(const int32_t e) {
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// The first value this approximation fails for is 2^1651 which is just greater than 10^297.
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BOOST_ASSERT(e >= 0);
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BOOST_ASSERT(e <= 1650);
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return (((uint32_t) e) * 78913) >> 18;
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}
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// Returns floor(log_10(5^e)).
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inline uint32_t log10Pow5(const int32_t e) {
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// The first value this approximation fails for is 5^2621 which is just greater than 10^1832.
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BOOST_ASSERT(e >= 0);
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BOOST_ASSERT(e <= 2620);
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return (((uint32_t) e) * 732923) >> 20;
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}
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inline int copy_special_str(char * const result, const bool sign, const bool exponent, const bool mantissa) {
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if (mantissa) {
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memcpy(result, "NaN", 3);
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return 3;
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}
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if (sign) {
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result[0] = '-';
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}
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if (exponent) {
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memcpy(result + sign, "Infinity", 8);
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return sign + 8;
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}
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memcpy(result + sign, "0E0", 3);
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return sign + 3;
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}
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inline uint32_t float_to_bits(const float f) {
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uint32_t bits = 0;
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memcpy(&bits, &f, sizeof(float));
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return bits;
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}
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inline uint64_t double_to_bits(const double d) {
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uint64_t bits = 0;
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memcpy(&bits, &d, sizeof(double));
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return bits;
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}
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} // detail
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} // ryu
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} // detail
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BOOST_JSON_NS_END
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#endif
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