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https://github.com/fastfloat/fast_float.git
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1a15c66fb9
manually checked modified files for errors, but not committing .clang-format due to the following warning: >>> Setting `QualifierAlignment` to something other than `Leave`, COULD lead to incorrect code formatting due to incorrect decisions made due to clang-formats lack of complete semantic information. As such extra care should be taken to review code changes made by the use of this option.
117 lines
3.4 KiB
C++
117 lines
3.4 KiB
C++
#include "fast_float/fast_float.h"
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#include <cassert>
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#include <cmath>
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#include <cstdio>
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#include <ios>
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#include <iostream>
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#include <limits>
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#include <system_error>
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template <typename T> char *to_string(T d, char *buffer) {
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auto written = std::snprintf(buffer, 64, "%.*e",
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std::numeric_limits<T>::max_digits10 - 1, d);
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return buffer + written;
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}
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static fast_float::value128 g_lehmer64_state;
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/**
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* D. H. Lehmer, Mathematical methods in large-scale computing units.
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* Proceedings of a Second Symposium on Large Scale Digital Calculating
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* Machinery;
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* Annals of the Computation Laboratory, Harvard Univ. 26 (1951), pp. 141-146.
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*
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* P L'Ecuyer, Tables of linear congruential generators of different sizes and
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* good lattice structure. Mathematics of Computation of the American
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* Mathematical
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* Society 68.225 (1999): 249-260.
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*/
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static inline void lehmer64_seed(uint64_t seed) {
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g_lehmer64_state.high = 0;
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g_lehmer64_state.low = seed;
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}
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static inline uint64_t lehmer64() {
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fast_float::value128 v = fast_float::full_multiplication(
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g_lehmer64_state.low, UINT64_C(0xda942042e4dd58b5));
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v.high += g_lehmer64_state.high * UINT64_C(0xda942042e4dd58b5);
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g_lehmer64_state = v;
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return v.high;
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}
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size_t errors;
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void random_values(size_t N) {
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char buffer[64];
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lehmer64_seed(N);
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for (size_t t = 0; t < N; t++) {
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if ((t % 1048576) == 0) {
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std::cout << ".";
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std::cout.flush();
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}
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uint64_t word = lehmer64();
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double v;
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memcpy(&v, &word, sizeof(v));
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// if (!std::isnormal(v))
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{
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char const *string_end = to_string(v, buffer);
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double result_value;
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auto result = fast_float::from_chars(buffer, string_end, result_value);
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// Starting with version 4.0 for fast_float, we return result_out_of_range
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// if the value is either too small (too close to zero) or too large
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// (effectively infinity). So std::errc::result_out_of_range is normal for
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// well-formed input strings.
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if (result.ec != std::errc() &&
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result.ec != std::errc::result_out_of_range) {
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std::cerr << "parsing error ? " << buffer << std::endl;
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errors++;
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if (errors > 10) {
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abort();
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}
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continue;
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}
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if (std::isnan(v)) {
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if (!std::isnan(result_value)) {
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std::cerr << "not nan" << buffer << std::endl;
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errors++;
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if (errors > 10) {
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abort();
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}
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}
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} else if (copysign(1, result_value) != copysign(1, v)) {
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std::cerr << buffer << std::endl;
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std::cerr << "I got " << std::hexfloat << result_value
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<< " but I was expecting " << v << std::endl;
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abort();
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} else if (result_value != v) {
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std::cerr << "no match ? " << buffer << std::endl;
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std::cout << "started with " << std::hexfloat << v << std::endl;
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std::cout << "got back " << std::hexfloat << result_value << std::endl;
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std::cout << std::dec;
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errors++;
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if (errors > 10) {
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abort();
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}
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}
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}
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}
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std::cout << std::endl;
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}
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int main() {
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errors = 0;
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size_t N =
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size_t(1) << (sizeof(size_t) * 4); // shift: 32 for 64bit, 16 for 32bit
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random_values(N);
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if (errors == 0) {
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std::cout << std::endl;
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std::cout << "all ok" << std::endl;
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return EXIT_SUCCESS;
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}
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std::cerr << std::endl;
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std::cerr << "errors were encountered" << std::endl;
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return EXIT_FAILURE;
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}
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