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# cleanup and speedup digit_comp.

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This commit is contained in:
IRainman 2025-10-21 21:49:21 +03:00
parent 0e123c5e82
commit 487799ede2
1 changed files with 13 additions and 13 deletions
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26
include/fast_float/digit_comparison.h
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@ -345,18 +345,18 @@ parse_mantissa(bigint &result, const parsed_number_string_t<UC> &num) noexcept {
} }
template <typename T> template <typename T>
inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa positive_digit_comp( fastfloat_really_inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa
bigint &bigmant, am_pow_t const exponent) noexcept { positive_digit_comp(
bigint &bigmant, adjusted_mantissa& am, am_pow_t const exponent) noexcept {
FASTFLOAT_ASSERT(bigmant.pow10(exponent)); FASTFLOAT_ASSERT(bigmant.pow10(exponent));
adjusted_mantissa answer;
bool truncated; bool truncated;
answer.mantissa = bigmant.hi64(truncated); am.mantissa = bigmant.hi64(truncated);
constexpr am_pow_t bias = binary_format<T>::mantissa_explicit_bits() - constexpr am_pow_t bias = binary_format<T>::mantissa_explicit_bits() -
binary_format<T>::minimum_exponent(); binary_format<T>::minimum_exponent();
answer.power2 = am.power2 =
static_cast<fast_float::am_pow_t>(bigmant.bit_length() - 64 + bias); static_cast<fast_float::am_pow_t>(bigmant.bit_length() - 64 + bias);
round<T>(answer, [truncated](adjusted_mantissa &a, am_pow_t shift) { round<T>(am, [truncated](adjusted_mantissa &a, am_pow_t shift) {
round_nearest_tie_even( round_nearest_tie_even(
a, shift, a, shift,
[truncated](bool is_odd, bool is_halfway, bool is_above) -> bool { [truncated](bool is_odd, bool is_halfway, bool is_above) -> bool {
@ -365,7 +365,7 @@ inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa positive_digit_comp(
}); });
}); });
return answer; return am;
} }
// the scaling here is quite simple: we have, for the real digits `m * 10^e`, // the scaling here is quite simple: we have, for the real digits `m * 10^e`,
@ -374,8 +374,9 @@ inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa positive_digit_comp(
// we then need to scale by `2^(f- e)`, and then the two significant digits // we then need to scale by `2^(f- e)`, and then the two significant digits
// are of the same magnitude. // are of the same magnitude.
template <typename T> template <typename T>
inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa negative_digit_comp( fastfloat_really_inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa
bigint &bigmant, adjusted_mantissa am, am_pow_t const exponent) noexcept { negative_digit_comp(
bigint &bigmant, adjusted_mantissa& am, am_pow_t const exponent) noexcept {
bigint &real_digits = bigmant; bigint &real_digits = bigmant;
am_pow_t const &real_exp = exponent; am_pow_t const &real_exp = exponent;
@ -411,7 +412,6 @@ inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa negative_digit_comp(
// compare digits, and use it to direct rounding // compare digits, and use it to direct rounding
int ord = real_digits.compare(theor_digits); int ord = real_digits.compare(theor_digits);
adjusted_mantissa answer = am;
round<T>(am, [ord](adjusted_mantissa &a, am_pow_t shift) { round<T>(am, [ord](adjusted_mantissa &a, am_pow_t shift) {
round_nearest_tie_even( round_nearest_tie_even(
a, shift, [ord](bool is_odd, bool _, bool __) -> bool { a, shift, [ord](bool is_odd, bool _, bool __) -> bool {
@ -427,7 +427,7 @@ inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa negative_digit_comp(
}); });
}); });
return answer; return am;
} }
// parse the significant digits as a big integer to unambiguously round // parse the significant digits as a big integer to unambiguously round
@ -445,7 +445,7 @@ inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa negative_digit_comp(
// of both, and use that to direct rounding. // of both, and use that to direct rounding.
template <typename T, typename UC> template <typename T, typename UC>
inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa digit_comp( inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa digit_comp(
parsed_number_string_t<UC> const &num, adjusted_mantissa am) noexcept { parsed_number_string_t<UC> const &num, adjusted_mantissa& am) noexcept {
// remove the invalid exponent bias // remove the invalid exponent bias
am.power2 -= invalid_am_bias; am.power2 -= invalid_am_bias;
@ -456,7 +456,7 @@ inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa digit_comp(
am_pow_t const exponent = am_pow_t const exponent =
static_cast<am_pow_t>(sci_exp + 1 - static_cast<am_pow_t>(digits)); static_cast<am_pow_t>(sci_exp + 1 - static_cast<am_pow_t>(digits));
if (exponent >= 0) { if (exponent >= 0) {
return positive_digit_comp<T>(bigmant, exponent); return positive_digit_comp<T>(bigmant, am, exponent);
} else { } else {
return negative_digit_comp<T>(bigmant, am, exponent); return negative_digit_comp<T>(bigmant, am, exponent);
} }