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Simplify FP formatting and follow coding conventions

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This commit is contained in:
Victor Zverovich 2020-09-30 06:27:48 -07:00
parent 6f3536f974
commit 575f401896
1 changed files with 29 additions and 104 deletions
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129
include/fmt/format-inl.h
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@ -1629,48 +1629,6 @@ struct fixed_handler {
}
};
// The shortest representation digit handler.
struct grisu_shortest_handler {
char* buf;
int size;
// Distance between scaled value and upper bound (wp_W in Grisu3).
uint64_t diff;
digits::result on_start(uint64_t, uint64_t, uint64_t, int&) {
return digits::more;
}
// Decrement the generated number approaching value from above.
void round(uint64_t d, uint64_t divisor, uint64_t& remainder,
uint64_t error) {
while (
remainder < d && error - remainder >= divisor &&
(remainder + divisor < d || d - remainder >= remainder + divisor - d)) {
--buf[size - 1];
remainder += divisor;
}
}
// Implements Grisu's round_weed.
digits::result on_digit(char digit, uint64_t divisor, uint64_t remainder,
uint64_t error, int exp, bool integral) {
buf[size++] = digit;
if (remainder >= error) return digits::more;
uint64_t unit = integral ? 1 : data::powers_of_10_64[-exp];
uint64_t up = (diff - 1) * unit; // wp_Wup
round(up, divisor, remainder, error);
uint64_t down = (diff + 1) * unit; // wp_Wdown
if (remainder < down && error - remainder >= divisor &&
(remainder + divisor < down ||
down - remainder > remainder + divisor - down)) {
return digits::error;
}
return 2 * unit <= remainder && remainder <= error - 4 * unit
? digits::done
: digits::error;
}
};
// Implementation of Dragonbox algorithm: https://github.com/jk-jeon/dragonbox.
namespace dragonbox {
// Computes 128-bit result of multiplication of two 64-bit unsigned integers.
@ -1827,27 +1785,17 @@ bool check_divisibility_and_divide_by_pow5(uint32_t& n) FMT_NOEXCEPT {
return result;
}
// Computes floor(n / 10^N) for small n and N
// Precondition: n <= 10^(N+1)
template <int N> struct small_division_by_pow10_info;
template <> struct small_division_by_pow10_info<1> {
static const uint32_t magic_number = 0xcccd;
static const int shift_amount = 19;
static const int divisor_times_10 = 100;
};
template <> struct small_division_by_pow10_info<2> {
static const uint32_t magic_number = 0xa3d8;
static const int shift_amount = 22;
static const int divisor_times_10 = 1000;
};
// Computes floor(n / pow(10, N)) for small n and N.
// Precondition: n <= pow(10, N + 1).
template <int N> uint32_t small_division_by_pow10(uint32_t n) FMT_NOEXCEPT {
FMT_ASSERT(n <= small_division_by_pow10_info<N>::divisor_times_10,
"n is too large");
return (n * small_division_by_pow10_info<N>::magic_number) >>
small_division_by_pow10_info<N>::shift_amount;
static constexpr struct {
uint32_t magic_number;
int shift_amount;
int divisor_times_10;
} infos[] = {{0xcccd, 19, 100}, {0xa3d8, 22, 1000}};
constexpr auto info = infos[N - 1];
FMT_ASSERT(n <= info.divisor_times_10, "n is too large");
return n * info.magic_number >> info.shift_amount;
}
// Computes floor(n / 10^(kappa + 1)) (float)
@ -2026,39 +1974,26 @@ bool is_left_endpoint_integer_shorter_interval(int exponent) FMT_NOEXCEPT {
template <class T>
bool is_endpoint_integer(typename float_info<T>::carrier_uint two_f,
int exponent, int minus_k) FMT_NOEXCEPT {
if (exponent < float_info<T>::case_fc_pm_half_lower_threshold) {
return false;
}
// For k >= 0
else if (exponent <= float_info<T>::case_fc_pm_half_upper_threshold) {
return true;
}
// For k < 0
else if (exponent > float_info<T>::divisibility_check_by_5_threshold) {
return false;
} else {
if (exponent < float_info<T>::case_fc_pm_half_lower_threshold) return false;
// For k >= 0.
if (exponent <= float_info<T>::case_fc_pm_half_upper_threshold) return true;
// For k < 0.
if (exponent > float_info<T>::divisibility_check_by_5_threshold) return false;
return divisible_by_power_of_5(two_f, minus_k);
}
}
template <class T>
bool is_center_integer(typename float_info<T>::carrier_uint two_f, int exponent,
int minus_k) FMT_NOEXCEPT {
// Exponent for 5 is negative
if (exponent > float_info<T>::divisibility_check_by_5_threshold) {
return false;
} else if (exponent > float_info<T>::case_fc_upper_threshold) {
// Exponent for 5 is negative.
if (exponent > float_info<T>::divisibility_check_by_5_threshold) return false;
if (exponent > float_info<T>::case_fc_upper_threshold)
return divisible_by_power_of_5(two_f, minus_k);
}
// Both exponents are nonnegative
else if (exponent >= float_info<T>::case_fc_lower_threshold) {
return true;
}
// Exponent for 2 is negative
else {
// Both exponents are nonnegative.
if (exponent >= float_info<T>::case_fc_lower_threshold) return true;
// Exponent for 2 is negative.
return divisible_by_power_of_2(two_f, minus_k - exponent + 1);
}
}
// Remove trailing zeros from n and return the number of zeros removed (float)
FMT_ALWAYS_INLINE int remove_trailing_zeros(uint32_t& n) FMT_NOEXCEPT {
@ -2067,9 +2002,8 @@ FMT_ALWAYS_INLINE int remove_trailing_zeros(uint32_t& n) FMT_NOEXCEPT {
#else
int t = ctz(n);
#endif
if (t > float_info<float>::max_trailing_zeros) {
if (t > float_info<float>::max_trailing_zeros)
t = float_info<float>::max_trailing_zeros;
}
const uint32_t mod_inv1 = 0xcccccccd;
const uint32_t max_quotient1 = 0x33333333;
@ -2078,9 +2012,7 @@ FMT_ALWAYS_INLINE int remove_trailing_zeros(uint32_t& n) FMT_NOEXCEPT {
int s = 0;
for (; s < t - 1; s += 2) {
if (n * mod_inv2 > max_quotient2) {
break;
}
if (n * mod_inv2 > max_quotient2) break;
n *= mod_inv2;
}
if (s < t && n * mod_inv1 <= max_quotient1) {
@ -2098,9 +2030,8 @@ FMT_ALWAYS_INLINE int remove_trailing_zeros(uint64_t& n) FMT_NOEXCEPT {
#else
int t = ctzll(n);
#endif
if (t > float_info<double>::max_trailing_zeros) {
if (t > float_info<double>::max_trailing_zeros)
t = float_info<double>::max_trailing_zeros;
}
// Divide by 10^8 and reduce to 32-bits
// Since ret_value.significand <= (2^64 - 1) / 1000 < 10^17,
// both of the quotient and the r should fit in 32-bits
@ -2119,9 +2050,7 @@ FMT_ALWAYS_INLINE int remove_trailing_zeros(uint64_t& n) FMT_NOEXCEPT {
int s = 8;
for (; s < t; ++s) {
if (quotient * mod_inv1 > max_quotient1) {
break;
}
if (quotient * mod_inv1 > max_quotient1) break;
quotient *= mod_inv1;
}
quotient >>= (s - 8);
@ -2198,9 +2127,7 @@ FMT_ALWAYS_INLINE FMT_SAFEBUFFERS decimal_fp<T> shorter_interval_case(
cache, beta_minus_1);
// If the left endpoint is not an integer, increase it
if (!is_left_endpoint_integer_shorter_interval<T>(exponent)) {
++xi;
}
if (!is_left_endpoint_integer_shorter_interval<T>(exponent)) ++xi;
// Try bigger divisor
ret_value.significand = zi / 10;
@ -2258,9 +2185,7 @@ FMT_SAFEBUFFERS decimal_fp<T> to_decimal(T x) FMT_NOEXCEPT {
(static_cast<carrier_uint>(1) << float_info<T>::significand_bits);
} else {
// Subnormal case; the interval is always regular.
if (significand == 0) {
return decimal_fp<T>{0, 0};
}
if (significand == 0) return {0, 0};
exponent = float_info<T>::min_exponent - float_info<T>::significand_bits;
}