fmtlib/fmt
1
0
Fork 1
mirror of https://github.com/fmtlib/fmt.git synced 2025-12-02 07:09:44 +01:00
Code Issues Packages Projects Releases Wiki Activity

Use digit pairs as in unrolledlut

Browse Source
This commit is contained in:
Victor Zverovich
2020-06-27 12:05:38 -07:00
parent a6f8e7d860
commit ba363b3a24
2 changed files with 28 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
include/fmt/format.h
View File

@@ -752,7 +752,9 @@ template <typename T = void> struct FMT_EXTERN_TEMPLATE_API basic_data {
static const uint64_t zero_or_powers_of_10_64[];
static const uint64_t pow10_significands[];
static const int16_t pow10_exponents[];
static const char digits[];
// GCC generates slightly better code for pairs than chars.
using digit_pair = char[2];
static const digit_pair digits[];
static const char hex_digits[];
static const char foreground_color[];
static const char background_color[];
@@ -903,7 +905,7 @@ inline format_decimal_result<Char*> format_decimal(Char* out, UInt value,
// of for every digit. The idea comes from the talk by Alexandrescu
// "Three Optimization Tips for C++". See speed-test for a comparison.
out -= 2;
copy2(out, data::digits + static_cast<unsigned>((value % 100) * 2));
copy2(out, data::digits[value % 100]);
value /= 100;
}
if (value < 10) {
@@ -911,7 +913,7 @@ inline format_decimal_result<Char*> format_decimal(Char* out, UInt value,
return {out, end};
}
out -= 2;
copy2(out, data::digits + static_cast<unsigned>(value * 2));
copy2(out, data::digits[value]);
return {out, end};
}
@@ -1085,12 +1087,12 @@ template <typename Char, typename It> It write_exponent(int exp, It it) {
*it++ = static_cast<Char>('+');
}
if (exp >= 100) {
const char* top = data::digits + (exp / 100) * 2;
const char* top = data::digits[exp / 100];
if (exp >= 1000) *it++ = static_cast<Char>(top[0]);
*it++ = static_cast<Char>(top[1]);
exp %= 100;
}
const char* d = data::digits + exp * 2;
const char* d = data::digits[exp];
*it++ = static_cast<Char>(d[0]);
*it++ = static_cast<Char>(d[1]);
return it;