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Restructure float_format

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This commit is contained in:
Victor Zverovich 2020-01-07 14:20:21 -10:00
parent 9e3f3e8cff
commit 0201c8db21
1 changed files with 20 additions and 20 deletions
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40
include/fmt/format-inl.h
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@ -457,7 +457,7 @@ inline fp operator*(fp x, fp y) { return {multiply(x.f, y.f), x.e + y.e + 64}; }
// Returns a cached power of 10 `c_k = c_k.f * pow(2, c_k.e)` such that its
// (binary) exponent satisfies `min_exponent <= c_k.e <= min_exponent + 28`.
FMT_FUNC fp get_cached_power(int min_exponent, int& pow10_exponent) {
inline fp get_cached_power(int min_exponent, int& pow10_exponent) {
const uint64_t one_over_log2_10 = 0x4d104d42; // round(pow(2, 32) / log2(10))
int index = static_cast<int>(
static_cast<int64_t>(
@ -1043,25 +1043,7 @@ int format_float(T value, int precision, float_specs specs, buffer<char>& buf) {
int exp = 0;
const int min_exp = -60; // alpha in Grisu.
int cached_exp10 = 0; // K in Grisu.
if (precision != -1) {
if (precision > 17) return snprintf_float(value, precision, specs, buf);
fp normalized = normalize(fp(value));
const auto cached_pow = get_cached_power(
min_exp - (normalized.e + fp::significand_size), cached_exp10);
normalized = normalized * cached_pow;
fixed_handler handler{buf.data(), 0, precision, -cached_exp10, fixed};
if (grisu_gen_digits(normalized, 1, exp, handler) == digits::error)
return snprintf_float(value, precision, specs, buf);
int num_digits = handler.size;
if (!fixed) {
// Remove trailing zeros.
while (num_digits > 0 && buf[num_digits - 1] == '0') {
--num_digits;
++exp;
}
}
buf.resize(to_unsigned(num_digits));
} else {
if (precision < 0) {
fp fp_value;
auto boundaries = specs.binary32
? fp_value.assign_float_with_boundaries(value)
@ -1090,6 +1072,24 @@ int format_float(T value, int precision, float_specs specs, buffer<char>& buf) {
return exp;
}
buf.resize(to_unsigned(handler.size));
} else {
if (precision > 17) return snprintf_float(value, precision, specs, buf);
fp normalized = normalize(fp(value));
const auto cached_pow = get_cached_power(
min_exp - (normalized.e + fp::significand_size), cached_exp10);
normalized = normalized * cached_pow;
fixed_handler handler{buf.data(), 0, precision, -cached_exp10, fixed};
if (grisu_gen_digits(normalized, 1, exp, handler) == digits::error)
return snprintf_float(value, precision, specs, buf);
int num_digits = handler.size;
if (!fixed) {
// Remove trailing zeros.
while (num_digits > 0 && buf[num_digits - 1] == '0') {
--num_digits;
++exp;
}
}
buf.resize(to_unsigned(num_digits));
}
return exp - cached_exp10;
}