mirror of
https://github.com/RetroDECK/Duckstation.git
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459 lines
15 KiB
C++
459 lines
15 KiB
C++
#ifndef FASTFLOAT_FLOAT_COMMON_H
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#define FASTFLOAT_FLOAT_COMMON_H
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#include <cfloat>
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#include <cstdint>
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#include <cassert>
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#include <cstring>
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#include <type_traits>
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#if (defined(__x86_64) || defined(__x86_64__) || defined(_M_X64) \
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|| defined(__amd64) || defined(__aarch64__) || defined(_M_ARM64) \
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|| defined(__MINGW64__) \
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|| defined(__s390x__) \
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|| (defined(__ppc64__) || defined(__PPC64__) || defined(__ppc64le__) || defined(__PPC64LE__)) )
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#define FASTFLOAT_64BIT 1
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#elif (defined(__i386) || defined(__i386__) || defined(_M_IX86) \
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|| defined(__arm__) || defined(_M_ARM) \
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|| defined(__MINGW32__) || defined(__EMSCRIPTEN__))
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#define FASTFLOAT_32BIT 1
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#else
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// Need to check incrementally, since SIZE_MAX is a size_t, avoid overflow.
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// We can never tell the register width, but the SIZE_MAX is a good approximation.
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// UINTPTR_MAX and INTPTR_MAX are optional, so avoid them for max portability.
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#if SIZE_MAX == 0xffff
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#error Unknown platform (16-bit, unsupported)
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#elif SIZE_MAX == 0xffffffff
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#define FASTFLOAT_32BIT 1
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#elif SIZE_MAX == 0xffffffffffffffff
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#define FASTFLOAT_64BIT 1
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#else
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#error Unknown platform (not 32-bit, not 64-bit?)
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#endif
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#endif
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#if ((defined(_WIN32) || defined(_WIN64)) && !defined(__clang__))
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#include <intrin.h>
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#endif
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#if defined(_MSC_VER) && !defined(__clang__)
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#define FASTFLOAT_VISUAL_STUDIO 1
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#endif
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#if defined __BYTE_ORDER__ && defined __ORDER_BIG_ENDIAN__
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#define FASTFLOAT_IS_BIG_ENDIAN (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
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#elif defined _WIN32
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#define FASTFLOAT_IS_BIG_ENDIAN 0
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#else
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#if defined(__APPLE__) || defined(__FreeBSD__)
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#include <machine/endian.h>
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#elif defined(sun) || defined(__sun)
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#include <sys/byteorder.h>
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#else
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#ifdef __has_include
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#if __has_include(<endian.h>)
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#include <endian.h>
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#endif //__has_include(<endian.h>)
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#endif //__has_include
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#endif
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#
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#ifndef __BYTE_ORDER__
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// safe choice
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#define FASTFLOAT_IS_BIG_ENDIAN 0
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#endif
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#
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#ifndef __ORDER_LITTLE_ENDIAN__
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// safe choice
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#define FASTFLOAT_IS_BIG_ENDIAN 0
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#endif
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#
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#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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#define FASTFLOAT_IS_BIG_ENDIAN 0
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#else
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#define FASTFLOAT_IS_BIG_ENDIAN 1
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#endif
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#endif
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#ifdef FASTFLOAT_VISUAL_STUDIO
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#define fastfloat_really_inline __forceinline
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#else
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#define fastfloat_really_inline inline __attribute__((always_inline))
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#endif
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#ifndef FASTFLOAT_ASSERT
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#define FASTFLOAT_ASSERT(x) { if (!(x)) abort(); }
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#endif
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#ifndef FASTFLOAT_DEBUG_ASSERT
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#include <cassert>
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#define FASTFLOAT_DEBUG_ASSERT(x) assert(x)
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#endif
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// rust style `try!()` macro, or `?` operator
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#define FASTFLOAT_TRY(x) { if (!(x)) return false; }
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namespace fast_float {
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// Compares two ASCII strings in a case insensitive manner.
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inline bool fastfloat_strncasecmp(const char *input1, const char *input2,
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size_t length) {
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char running_diff{0};
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for (size_t i = 0; i < length; i++) {
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running_diff |= (input1[i] ^ input2[i]);
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}
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return (running_diff == 0) || (running_diff == 32);
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}
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#ifndef FLT_EVAL_METHOD
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#error "FLT_EVAL_METHOD should be defined, please include cfloat."
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#endif
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// a pointer and a length to a contiguous block of memory
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template <typename T>
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struct span {
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const T* ptr;
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size_t length;
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span(const T* _ptr, size_t _length) : ptr(_ptr), length(_length) {}
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span() : ptr(nullptr), length(0) {}
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constexpr size_t len() const noexcept {
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return length;
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}
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const T& operator[](size_t index) const noexcept {
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FASTFLOAT_DEBUG_ASSERT(index < length);
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return ptr[index];
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}
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};
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struct value128 {
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uint64_t low;
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uint64_t high;
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value128(uint64_t _low, uint64_t _high) : low(_low), high(_high) {}
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value128() : low(0), high(0) {}
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};
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/* result might be undefined when input_num is zero */
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fastfloat_really_inline int leading_zeroes(uint64_t input_num) {
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assert(input_num > 0);
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#ifdef FASTFLOAT_VISUAL_STUDIO
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#if defined(_M_X64) || defined(_M_ARM64)
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unsigned long leading_zero = 0;
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// Search the mask data from most significant bit (MSB)
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// to least significant bit (LSB) for a set bit (1).
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_BitScanReverse64(&leading_zero, input_num);
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return (int)(63 - leading_zero);
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#else
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int last_bit = 0;
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if(input_num & uint64_t(0xffffffff00000000)) input_num >>= 32, last_bit |= 32;
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if(input_num & uint64_t( 0xffff0000)) input_num >>= 16, last_bit |= 16;
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if(input_num & uint64_t( 0xff00)) input_num >>= 8, last_bit |= 8;
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if(input_num & uint64_t( 0xf0)) input_num >>= 4, last_bit |= 4;
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if(input_num & uint64_t( 0xc)) input_num >>= 2, last_bit |= 2;
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if(input_num & uint64_t( 0x2)) input_num >>= 1, last_bit |= 1;
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return 63 - last_bit;
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#endif
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#else
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return __builtin_clzll(input_num);
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#endif
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}
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#ifdef FASTFLOAT_32BIT
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// slow emulation routine for 32-bit
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fastfloat_really_inline uint64_t emulu(uint32_t x, uint32_t y) {
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return x * (uint64_t)y;
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}
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// slow emulation routine for 32-bit
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#if !defined(__MINGW64__)
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fastfloat_really_inline uint64_t _umul128(uint64_t ab, uint64_t cd,
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uint64_t *hi) {
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uint64_t ad = emulu((uint32_t)(ab >> 32), (uint32_t)cd);
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uint64_t bd = emulu((uint32_t)ab, (uint32_t)cd);
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uint64_t adbc = ad + emulu((uint32_t)ab, (uint32_t)(cd >> 32));
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uint64_t adbc_carry = !!(adbc < ad);
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uint64_t lo = bd + (adbc << 32);
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*hi = emulu((uint32_t)(ab >> 32), (uint32_t)(cd >> 32)) + (adbc >> 32) +
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(adbc_carry << 32) + !!(lo < bd);
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return lo;
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}
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#endif // !__MINGW64__
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#endif // FASTFLOAT_32BIT
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// compute 64-bit a*b
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fastfloat_really_inline value128 full_multiplication(uint64_t a,
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uint64_t b) {
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value128 answer;
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#if defined(_M_ARM64) && !defined(__MINGW32__)
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// ARM64 has native support for 64-bit multiplications, no need to emulate
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// But MinGW on ARM64 doesn't have native support for 64-bit multiplications
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answer.high = __umulh(a, b);
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answer.low = a * b;
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#elif defined(FASTFLOAT_32BIT) || (defined(_WIN64) && !defined(__clang__))
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answer.low = _umul128(a, b, &answer.high); // _umul128 not available on ARM64
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#elif defined(FASTFLOAT_64BIT)
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__uint128_t r = ((__uint128_t)a) * b;
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answer.low = uint64_t(r);
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answer.high = uint64_t(r >> 64);
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#else
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#error Not implemented
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#endif
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return answer;
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}
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struct adjusted_mantissa {
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uint64_t mantissa{0};
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int32_t power2{0}; // a negative value indicates an invalid result
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adjusted_mantissa() = default;
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bool operator==(const adjusted_mantissa &o) const {
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return mantissa == o.mantissa && power2 == o.power2;
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}
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bool operator!=(const adjusted_mantissa &o) const {
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return mantissa != o.mantissa || power2 != o.power2;
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}
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};
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// Bias so we can get the real exponent with an invalid adjusted_mantissa.
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constexpr static int32_t invalid_am_bias = -0x8000;
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constexpr static double powers_of_ten_double[] = {
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1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9, 1e10, 1e11,
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1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18, 1e19, 1e20, 1e21, 1e22};
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constexpr static float powers_of_ten_float[] = {1e0f, 1e1f, 1e2f, 1e3f, 1e4f, 1e5f,
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1e6f, 1e7f, 1e8f, 1e9f, 1e10f};
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// used for max_mantissa_double and max_mantissa_float
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constexpr uint64_t constant_55555 = 5 * 5 * 5 * 5 * 5;
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// Largest integer value v so that (5**index * v) <= 1<<53.
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// 0x10000000000000 == 1 << 53
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constexpr static uint64_t max_mantissa_double[] = {
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0x10000000000000,
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0x10000000000000 / 5,
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0x10000000000000 / (5 * 5),
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0x10000000000000 / (5 * 5 * 5),
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0x10000000000000 / (5 * 5 * 5 * 5),
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0x10000000000000 / (constant_55555),
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0x10000000000000 / (constant_55555 * 5),
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0x10000000000000 / (constant_55555 * 5 * 5),
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0x10000000000000 / (constant_55555 * 5 * 5 * 5),
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0x10000000000000 / (constant_55555 * 5 * 5 * 5 * 5),
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0x10000000000000 / (constant_55555 * constant_55555),
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0x10000000000000 / (constant_55555 * constant_55555 * 5),
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0x10000000000000 / (constant_55555 * constant_55555 * 5 * 5),
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0x10000000000000 / (constant_55555 * constant_55555 * 5 * 5 * 5),
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0x10000000000000 / (constant_55555 * constant_55555 * constant_55555),
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0x10000000000000 / (constant_55555 * constant_55555 * constant_55555 * 5),
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0x10000000000000 / (constant_55555 * constant_55555 * constant_55555 * 5 * 5),
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0x10000000000000 / (constant_55555 * constant_55555 * constant_55555 * 5 * 5 * 5),
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0x10000000000000 / (constant_55555 * constant_55555 * constant_55555 * 5 * 5 * 5 * 5),
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0x10000000000000 / (constant_55555 * constant_55555 * constant_55555 * constant_55555),
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0x10000000000000 / (constant_55555 * constant_55555 * constant_55555 * constant_55555 * 5),
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0x10000000000000 / (constant_55555 * constant_55555 * constant_55555 * constant_55555 * 5 * 5),
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0x10000000000000 / (constant_55555 * constant_55555 * constant_55555 * constant_55555 * 5 * 5 * 5),
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0x10000000000000 / (constant_55555 * constant_55555 * constant_55555 * constant_55555 * 5 * 5 * 5 * 5)};
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// Largest integer value v so that (5**index * v) <= 1<<24.
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// 0x1000000 == 1<<24
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constexpr static uint64_t max_mantissa_float[] = {
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0x1000000,
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0x1000000 / 5,
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0x1000000 / (5 * 5),
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0x1000000 / (5 * 5 * 5),
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0x1000000 / (5 * 5 * 5 * 5),
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0x1000000 / (constant_55555),
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0x1000000 / (constant_55555 * 5),
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0x1000000 / (constant_55555 * 5 * 5),
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0x1000000 / (constant_55555 * 5 * 5 * 5),
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0x1000000 / (constant_55555 * 5 * 5 * 5 * 5),
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0x1000000 / (constant_55555 * constant_55555),
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0x1000000 / (constant_55555 * constant_55555 * 5)};
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template <typename T> struct binary_format {
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using equiv_uint = typename std::conditional<sizeof(T) == 4, uint32_t, uint64_t>::type;
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static inline constexpr int mantissa_explicit_bits();
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static inline constexpr int minimum_exponent();
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static inline constexpr int infinite_power();
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static inline constexpr int sign_index();
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static inline constexpr int min_exponent_fast_path(); // used when fegetround() == FE_TONEAREST
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static inline constexpr int max_exponent_fast_path();
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static inline constexpr int max_exponent_round_to_even();
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static inline constexpr int min_exponent_round_to_even();
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static inline constexpr uint64_t max_mantissa_fast_path(int64_t power);
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static inline constexpr uint64_t max_mantissa_fast_path(); // used when fegetround() == FE_TONEAREST
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static inline constexpr int largest_power_of_ten();
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static inline constexpr int smallest_power_of_ten();
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static inline constexpr T exact_power_of_ten(int64_t power);
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static inline constexpr size_t max_digits();
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static inline constexpr equiv_uint exponent_mask();
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static inline constexpr equiv_uint mantissa_mask();
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static inline constexpr equiv_uint hidden_bit_mask();
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};
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template <> inline constexpr int binary_format<double>::min_exponent_fast_path() {
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#if (FLT_EVAL_METHOD != 1) && (FLT_EVAL_METHOD != 0)
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return 0;
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#else
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return -22;
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#endif
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}
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template <> inline constexpr int binary_format<float>::min_exponent_fast_path() {
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#if (FLT_EVAL_METHOD != 1) && (FLT_EVAL_METHOD != 0)
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return 0;
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#else
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return -10;
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#endif
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}
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template <> inline constexpr int binary_format<double>::mantissa_explicit_bits() {
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return 52;
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}
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template <> inline constexpr int binary_format<float>::mantissa_explicit_bits() {
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return 23;
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}
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template <> inline constexpr int binary_format<double>::max_exponent_round_to_even() {
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return 23;
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}
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template <> inline constexpr int binary_format<float>::max_exponent_round_to_even() {
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return 10;
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}
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template <> inline constexpr int binary_format<double>::min_exponent_round_to_even() {
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return -4;
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}
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template <> inline constexpr int binary_format<float>::min_exponent_round_to_even() {
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return -17;
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}
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template <> inline constexpr int binary_format<double>::minimum_exponent() {
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return -1023;
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}
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template <> inline constexpr int binary_format<float>::minimum_exponent() {
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return -127;
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}
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template <> inline constexpr int binary_format<double>::infinite_power() {
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return 0x7FF;
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}
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template <> inline constexpr int binary_format<float>::infinite_power() {
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return 0xFF;
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}
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template <> inline constexpr int binary_format<double>::sign_index() { return 63; }
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template <> inline constexpr int binary_format<float>::sign_index() { return 31; }
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template <> inline constexpr int binary_format<double>::max_exponent_fast_path() {
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return 22;
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}
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template <> inline constexpr int binary_format<float>::max_exponent_fast_path() {
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return 10;
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}
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template <> inline constexpr uint64_t binary_format<double>::max_mantissa_fast_path() {
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return uint64_t(2) << mantissa_explicit_bits();
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}
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template <> inline constexpr uint64_t binary_format<double>::max_mantissa_fast_path(int64_t power) {
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// caller is responsible to ensure that
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// power >= 0 && power <= 22
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//
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return max_mantissa_double[power];
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}
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template <> inline constexpr uint64_t binary_format<float>::max_mantissa_fast_path() {
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return uint64_t(2) << mantissa_explicit_bits();
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}
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template <> inline constexpr uint64_t binary_format<float>::max_mantissa_fast_path(int64_t power) {
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// caller is responsible to ensure that
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// power >= 0 && power <= 10
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//
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return max_mantissa_float[power];
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}
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template <>
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inline constexpr double binary_format<double>::exact_power_of_ten(int64_t power) {
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return powers_of_ten_double[power];
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}
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template <>
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inline constexpr float binary_format<float>::exact_power_of_ten(int64_t power) {
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return powers_of_ten_float[power];
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}
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template <>
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inline constexpr int binary_format<double>::largest_power_of_ten() {
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return 308;
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}
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template <>
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inline constexpr int binary_format<float>::largest_power_of_ten() {
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return 38;
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}
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template <>
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inline constexpr int binary_format<double>::smallest_power_of_ten() {
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return -342;
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}
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template <>
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inline constexpr int binary_format<float>::smallest_power_of_ten() {
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return -65;
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}
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template <> inline constexpr size_t binary_format<double>::max_digits() {
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return 769;
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}
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template <> inline constexpr size_t binary_format<float>::max_digits() {
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return 114;
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}
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template <> inline constexpr binary_format<float>::equiv_uint
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binary_format<float>::exponent_mask() {
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return 0x7F800000;
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}
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template <> inline constexpr binary_format<double>::equiv_uint
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binary_format<double>::exponent_mask() {
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return 0x7FF0000000000000;
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}
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template <> inline constexpr binary_format<float>::equiv_uint
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binary_format<float>::mantissa_mask() {
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return 0x007FFFFF;
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}
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template <> inline constexpr binary_format<double>::equiv_uint
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binary_format<double>::mantissa_mask() {
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return 0x000FFFFFFFFFFFFF;
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}
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template <> inline constexpr binary_format<float>::equiv_uint
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binary_format<float>::hidden_bit_mask() {
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return 0x00800000;
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}
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template <> inline constexpr binary_format<double>::equiv_uint
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binary_format<double>::hidden_bit_mask() {
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return 0x0010000000000000;
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}
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template<typename T>
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fastfloat_really_inline void to_float(bool negative, adjusted_mantissa am, T &value) {
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uint64_t word = am.mantissa;
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word |= uint64_t(am.power2) << binary_format<T>::mantissa_explicit_bits();
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word = negative
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? word | (uint64_t(1) << binary_format<T>::sign_index()) : word;
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#if FASTFLOAT_IS_BIG_ENDIAN == 1
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if (std::is_same<T, float>::value) {
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::memcpy(&value, (char *)&word + 4, sizeof(T)); // extract value at offset 4-7 if float on big-endian
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} else {
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::memcpy(&value, &word, sizeof(T));
|
|
}
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#else
|
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// For little-endian systems:
|
|
::memcpy(&value, &word, sizeof(T));
|
|
#endif
|
|
}
|
|
|
|
} // namespace fast_float
|
|
|
|
#endif
|