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Rewrote format_impl.h functions to work with both decimal and binary

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This commit is contained in:
Andreas Tsouchlos
2022-02-15 09:37:02 +01:00
parent c3eb1e2909
commit fa0fef37db
5 changed files with 60 additions and 137 deletions
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4
const_fmt/format.h
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@@ -42,12 +42,12 @@ constexpr inline void check_fmt_params() {
template <fmt_data_t fmt_data, std::integral arg_t>
constexpr inline void format_arg(char* dest, arg_t arg) {
const_fmt_detail::format_int<arg_t, fmt_data>(dest, arg);
const_fmt_detail::format_int<fmt_data>(dest, arg);
};
template <fmt_data_t fmt_data, std::floating_point arg_t>
constexpr inline void format_arg(char* dest, arg_t arg){
const_fmt_detail::format_float<arg_t, fmt_data>(dest, arg);
const_fmt_detail::format_float<fmt_data>(dest, arg);
};
// TODO: Error handling

86
const_fmt/format_impl.h
View File

@@ -58,22 +58,40 @@ inline int do_count_digits(uint64_t n) {
return t - (n < zero_or_powers_of_10[t]);
}
constexpr inline auto count_digits(uint64_t n) -> int {
if (!std::is_constant_evaluated()) {
return do_count_digits(n);
template <FormatType t_format_type>
constexpr inline auto count_digits_base(uint64_t n) -> int {
if constexpr (t_format_type == FormatType::b) {
int result = 0;
while (n) {
n = n >> 1;
result += 1;
}
return result;
} else {
if (!std::is_constant_evaluated()) {
return do_count_digits(n);
}
return count_digits_fallback(n);
}
return count_digits_fallback(n);
}
// Converts value in the range [0, 100) to a string.
constexpr inline const char* digits2(size_t value) {
// Converts value in the range [0, base^2) to a string.
template <FormatType t_format_type>
constexpr inline const char* digits2_base(size_t value) {
// GCC generates slightly better code when value is pointer-size.
return &"0001020304050607080910111213141516171819"
"2021222324252627282930313233343536373839"
"4041424344454647484950515253545556575859"
"6061626364656667686970717273747576777879"
"8081828384858687888990919293949596979899"[value * 2];
if constexpr (t_format_type == FormatType::b) {
return &"00011011"[value * 2];
} else {
return &"0001020304050607080910111213141516171819"
"2021222324252627282930313233343536373839"
"4041424344454647484950515253545556575859"
"6061626364656667686970717273747576777879"
"8081828384858687888990919293949596979899"[value * 2];
}
}
@@ -86,9 +104,13 @@ constexpr inline void copy2(char* dst, const char* src) {
*dst = static_cast<char>(*src);
}
template <typename uint_t>
constexpr inline void format_decimal(char* out, uint_t value, int n_digits,
int size) {
template <FormatType t_format_type, typename uint_t>
constexpr inline void format_base(char* out, uint_t value, int n_digits,
int size) {
constexpr unsigned divisor = (t_format_type == FormatType::b) ? 2 : 10;
constexpr unsigned square_divisor = const_pow(divisor, 2);
if (n_digits > size) {
for (int i = 0; i < size; ++i) {
*(out++) = 'f';
@@ -97,19 +119,20 @@ constexpr inline void format_decimal(char* out, uint_t value, int n_digits,
}
out += size;
while (value >= 100) {
while (value >= square_divisor) {
out -= 2;
copy2(out, digits2(static_cast<size_t>(value % 100)));
value /= 100;
copy2(out, digits2_base<t_format_type>(
static_cast<size_t>(value % square_divisor)));
value /= square_divisor;
}
if (value < 10) {
if (value < divisor) {
*--out = static_cast<char>('0' + value);
return;
}
out -= 2;
copy2(out, digits2(static_cast<size_t>(value)));
copy2(out, digits2_base<t_format_type>(static_cast<size_t>(value)));
}
// returns {abs_value, was_negative}
@@ -139,19 +162,22 @@ constexpr std::pair<int_t, bool> get_abs_value(int_t value) {
*/
template <std::unsigned_integral uint_t, fmt_data_t t_fmt_node>
template <fmt_data_t t_fmt_node, std::unsigned_integral uint_t>
constexpr inline void format_int(char* out, uint_t value) {
format_decimal(out, value, count_digits(value), t_fmt_node.length);
// format_decimal(out, value, count_digits(value), t_fmt_node.length);
format_base<t_fmt_node.type>(out, value, count_digits_base<t_fmt_node.type>(value),
t_fmt_node.length);
}
template <std::signed_integral int_t, fmt_data_t t_fmt_node>
template <fmt_data_t t_fmt_node, std::signed_integral int_t>
constexpr inline void format_int(char* out, int_t value) {
const auto [abs_value, negative] = get_abs_value(value);
const std::size_t n_digits = count_digits(abs_value);
const std::size_t n_digits = count_digits_base<t_fmt_node.type>(abs_value);
format_decimal(out + 1 * (negative), abs_value, n_digits,
t_fmt_node.length - 1 * (negative));
format_base<t_fmt_node.type>(out + 1 * (negative), abs_value, n_digits,
t_fmt_node.length - 1 * (negative));
if constexpr (t_fmt_node.has_zero_padding) {
if (negative) *(out) = '-';
@@ -169,21 +195,21 @@ constexpr inline void format_int(char* out, int_t value) {
*/
template <std::floating_point float_t, fmt_data_t t_fmt_node>
template <fmt_data_t t_fmt_node, std::floating_point float_t>
constexpr inline void format_float(char* out, float_t value) {
// clang-format off
constexpr fmt_data_t fmt_node_integral = {
t_fmt_node.has_zero_padding, // has_zero_padding
t_fmt_node.length - t_fmt_node.precision - 1, // length
t_fmt_node.precision, // ignored
t_fmt_node.type, // ignored
FormatType::d, // type
t_fmt_node.position // ignored
};
constexpr fmt_data_t fmt_node_fractional = {
true, // has_zero_padding
t_fmt_node.precision, // length
t_fmt_node.precision, // ignored
t_fmt_node.type, // ignored
FormatType::d, // type
t_fmt_node.position // ignored
};
// clang-format on
@@ -198,8 +224,8 @@ constexpr inline void format_float(char* out, float_t value) {
const auto [fractional_abs, fractional_negative] =
get_abs_value(fractional);
format_int<int, fmt_node_integral>(out, integral);
format_int<uint16_t, fmt_node_fractional>(
format_int<fmt_node_integral, int>(out, integral);
format_int<fmt_node_fractional, uint16_t>(
out + t_fmt_node.length - t_fmt_node.precision, fractional_abs);
}