mirror of
https://github.com/fastfloat/fast_float.git
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103 lines
2.8 KiB
C++
103 lines
2.8 KiB
C++
#include "fast_float/fast_float.h"
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#include <cassert>
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#include <cmath>
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template <typename T> char *to_string(T d, char *buffer) {
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auto written = std::snprintf(buffer, 128, "%.*e",
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64, 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(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[128];
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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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{
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const char *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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if (result.ec != std::errc()) {
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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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}
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if(copysign(1,result_value) != copysign(1,v)) {
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std::cerr << "I got " << std::hexfloat << result_value << " but I was expecting " << v
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<< std::endl;
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abort();
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} else 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 (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 = size_t(1) << 32;
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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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