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Add FASTFLOAT_HAS_BYTESWAP check.

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Improve FASTFLOAT_CONSTEVAL20 usage for older standards.
This commit is contained in:
IRainman 2025-03-09 22:55:04 +03:00
parent 354f4c3eac
commit 63eb578d52
2 changed files with 29 additions and 14 deletions
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29
include/fast_float/ascii_number.h
View File

@ -35,12 +35,14 @@ fastfloat_really_inline constexpr bool is_integer(UC c) noexcept {
return !(c > UC('9') || c < UC('0'));
}
#if FASTFLOAT_HAS_BYTESWAP == 0
fastfloat_really_inline constexpr uint64_t byteswap(uint64_t val) {
return (val & 0xFF00000000000000) >> 56 | (val & 0x00FF000000000000) >> 40 |
(val & 0x0000FF0000000000) >> 24 | (val & 0x000000FF00000000) >> 8 |
(val & 0x00000000FF000000) << 8 | (val & 0x0000000000FF0000) << 24 |
(val & 0x000000000000FF00) << 40 | (val & 0x00000000000000FF) << 56;
}
#endif
// Read 8 UC into a u64. Truncates UC if not char.
template <typename UC>
@ -58,7 +60,11 @@ read8_to_u64(UC const *chars) {
::memcpy(&val, chars, sizeof(uint64_t));
#if FASTFLOAT_IS_BIG_ENDIAN == 1
// Need to read as-if the number was in little-endian order.
val = byteswap(val);
val =
#if FASTFLOAT_HAS_BYTESWAP == 1
std::
#endif
byteswap(val);
#endif
return val;
}
@ -382,25 +388,28 @@ parse_number_string(UC const *p, UC const *pend,
if ((uint64_t(options.format & chars_format::scientific) && (p != pend) &&
((UC('e') == *p) || (UC('E') == *p)))
#ifndef FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN
|| (uint64_t(options.format & detail::basic_fortran_fmt) && (p != pend) &&
((UC('+') == *p) || (UC('-') == *p) || (UC('d') == *p) ||
(UC('D') == *p)))
|| (uint64_t(options.format & detail::basic_fortran_fmt) &&
((UC('+') == *p) || (UC('-') == *p) ||
(UC('d') == *p) || (UC('D') == *p)))
#endif
) {
UC const *location_of_e = p;
if ((UC('e') == *p) || (UC('E') == *p) || (UC('d') == *p) ||
(UC('D') == *p)) {
if (((UC('e') == *p) || (UC('E') == *p))
#ifndef FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN
|| (UC('d') == *p) || (UC('D') == *p)
#endif
) {
++p;
}
bool neg_exp = false;
if ((p != pend) && (UC('-') == *p)) {
if (p != pend) {
if ( UC('-') == *p) {
neg_exp = true;
++p;
} else if ((p != pend) &&
(UC('+') ==
*p)) { // '+' on exponent is allowed by C++17 20.19.3.(7.1)
} else if (UC('+') == *p) { // '+' on exponent is allowed by C++17 20.19.3.(7.1)
++p;
}
}
if ((p == pend) || !is_integer(*p)) {
if (!uint64_t(options.format & chars_format::fixed)) {
// The exponential part is invalid for scientific notation, so it must

8
include/fast_float/constexpr_feature_detect.h
View File

@ -27,6 +27,12 @@
#define FASTFLOAT_HAS_IS_CONSTANT_EVALUATED 0
#endif
#if defined(__cpp_lib_byteswap)
#define FASTFLOAT_HAS_BYTESWAP 1
#else
#define FASTFLOAT_HAS_BYTESWAP 0
#endif
// Testing for relevant C++20 constexpr library features
#if FASTFLOAT_HAS_IS_CONSTANT_EVALUATED && FASTFLOAT_HAS_BIT_CAST && \
defined(__cpp_lib_constexpr_algorithms) && \
@ -36,7 +42,7 @@
#define FASTFLOAT_IS_CONSTEXPR 1
#else
#define FASTFLOAT_CONSTEXPR20
#define FASTFLOAT_CONSTEVAL20
#define FASTFLOAT_CONSTEVAL20 FASTFLOAT_CONSTEXPR14
#define FASTFLOAT_IS_CONSTEXPR 0
#endif