chromium/third_party/fast_float/src/include/fast_float/ascii_number.h

#ifndef FASTFLOAT_ASCII_NUMBER_H
#define FASTFLOAT_ASCII_NUMBER_H

#include <cctype>
#include <cstdint>
#include <cstring>
#include <iterator>
#include <limits>
#include <type_traits>

#include "float_common.h"

#ifdef FASTFLOAT_SSE2
#include <emmintrin.h>
#endif

#ifdef FASTFLOAT_NEON
#include <arm_neon.h>
#endif

namespace fast_float {

template <typename UC> fastfloat_really_inline constexpr bool has_simd_opt() { … }

// Next function can be micro-optimized, but compilers are entirely
// able to optimize it well.
template <typename UC>
fastfloat_really_inline constexpr bool is_integer(UC c) noexcept { … }

fastfloat_really_inline constexpr uint64_t byteswap(uint64_t val) { … }

// Read 8 UC into a u64. Truncates UC if not char.
template <typename UC>
fastfloat_really_inline FASTFLOAT_CONSTEXPR20 uint64_t
read8_to_u64(const UC *chars) { … }

#ifdef FASTFLOAT_SSE2

fastfloat_really_inline uint64_t simd_read8_to_u64(const __m128i data) { … }

fastfloat_really_inline uint64_t simd_read8_to_u64(const char16_t *chars) { … }

#elif defined(FASTFLOAT_NEON)

fastfloat_really_inline uint64_t simd_read8_to_u64(const uint16x8_t data) {
  FASTFLOAT_SIMD_DISABLE_WARNINGS
  uint8x8_t utf8_packed = vmovn_u16(data);
  return vget_lane_u64(vreinterpret_u64_u8(utf8_packed), 0);
  FASTFLOAT_SIMD_RESTORE_WARNINGS
}

fastfloat_really_inline uint64_t simd_read8_to_u64(const char16_t *chars) {
  FASTFLOAT_SIMD_DISABLE_WARNINGS
  return simd_read8_to_u64(
      vld1q_u16(reinterpret_cast<const uint16_t *>(chars)));
  FASTFLOAT_SIMD_RESTORE_WARNINGS
}

#endif // FASTFLOAT_SSE2

// MSVC SFINAE is broken pre-VS2017
#if defined(_MSC_VER) && _MSC_VER <= 1900
template <typename UC>
#else
template <typename UC, FASTFLOAT_ENABLE_IF(!has_simd_opt<UC>()) = 0>
#endif
// dummy for compile
uint64_t simd_read8_to_u64(UC const *) { … }

// credit  @aqrit
fastfloat_really_inline FASTFLOAT_CONSTEXPR14 uint32_t
parse_eight_digits_unrolled(uint64_t val) { … }

// Call this if chars are definitely 8 digits.
template <typename UC>
fastfloat_really_inline FASTFLOAT_CONSTEXPR20 uint32_t
parse_eight_digits_unrolled(UC const *chars) noexcept { … }

// credit @aqrit
fastfloat_really_inline constexpr bool
is_made_of_eight_digits_fast(uint64_t val) noexcept { … }

#ifdef FASTFLOAT_HAS_SIMD

// Call this if chars might not be 8 digits.
// Using this style (instead of is_made_of_eight_digits_fast() then
// parse_eight_digits_unrolled()) ensures we don't load SIMD registers twice.
fastfloat_really_inline FASTFLOAT_CONSTEXPR20 bool
simd_parse_if_eight_digits_unrolled(const char16_t *chars,
                                    uint64_t &i) noexcept { … }

#endif // FASTFLOAT_HAS_SIMD

// MSVC SFINAE is broken pre-VS2017
#if defined(_MSC_VER) && _MSC_VER <= 1900
template <typename UC>
#else
template <typename UC, FASTFLOAT_ENABLE_IF(!has_simd_opt<UC>()) = 0>
#endif
// dummy for compile
bool simd_parse_if_eight_digits_unrolled(UC const *, uint64_t &) { … }

template <typename UC, FASTFLOAT_ENABLE_IF(!std::is_same<UC, char>::value) = 0>
fastfloat_really_inline FASTFLOAT_CONSTEXPR20 void
loop_parse_if_eight_digits(const UC *&p, const UC *const pend, uint64_t &i) { … }

fastfloat_really_inline FASTFLOAT_CONSTEXPR20 void
loop_parse_if_eight_digits(const char *&p, const char *const pend,
                           uint64_t &i) { … }

enum class parse_error { … };

template <typename UC> struct parsed_number_string_t { … };

byte_span;
parsed_number_string;

template <typename UC>
fastfloat_really_inline FASTFLOAT_CONSTEXPR20 parsed_number_string_t<UC>
report_parse_error(UC const *p, parse_error error) { … }

// Assuming that you use no more than 19 digits, this will
// parse an ASCII string.
template <typename UC>
fastfloat_really_inline FASTFLOAT_CONSTEXPR20 parsed_number_string_t<UC>
parse_number_string(UC const *p, UC const *pend,
                    parse_options_t<UC> options) noexcept { … }

template <typename T, typename UC>
fastfloat_really_inline FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
parse_int_string(UC const *p, UC const *pend, T &value, int base) { … }

} // namespace fast_float

#endif