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//===------------------------- charconv.cpp -------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "charconv"
#include <string.h>
_LIBCPP_BEGIN_NAMESPACE_STD
namespace __itoa
{
static constexpr char cDigitsLut[200] = {
'0', '0', '0', '1', '0', '2', '0', '3', '0', '4', '0', '5', '0', '6', '0',
'7', '0', '8', '0', '9', '1', '0', '1', '1', '1', '2', '1', '3', '1', '4',
'1', '5', '1', '6', '1', '7', '1', '8', '1', '9', '2', '0', '2', '1', '2',
'2', '2', '3', '2', '4', '2', '5', '2', '6', '2', '7', '2', '8', '2', '9',
'3', '0', '3', '1', '3', '2', '3', '3', '3', '4', '3', '5', '3', '6', '3',
'7', '3', '8', '3', '9', '4', '0', '4', '1', '4', '2', '4', '3', '4', '4',
'4', '5', '4', '6', '4', '7', '4', '8', '4', '9', '5', '0', '5', '1', '5',
'2', '5', '3', '5', '4', '5', '5', '5', '6', '5', '7', '5', '8', '5', '9',
'6', '0', '6', '1', '6', '2', '6', '3', '6', '4', '6', '5', '6', '6', '6',
'7', '6', '8', '6', '9', '7', '0', '7', '1', '7', '2', '7', '3', '7', '4',
'7', '5', '7', '6', '7', '7', '7', '8', '7', '9', '8', '0', '8', '1', '8',
'2', '8', '3', '8', '4', '8', '5', '8', '6', '8', '7', '8', '8', '8', '9',
'9', '0', '9', '1', '9', '2', '9', '3', '9', '4', '9', '5', '9', '6', '9',
'7', '9', '8', '9', '9'};
template <typename T>
inline _LIBCPP_INLINE_VISIBILITY char*
append1(char* buffer, T i) noexcept
{
*buffer = '0' + static_cast<char>(i);
return buffer + 1;
}
template <typename T>
inline _LIBCPP_INLINE_VISIBILITY char*
append2(char* buffer, T i) noexcept
{
memcpy(buffer, &cDigitsLut[(i)*2], 2);
return buffer + 2;
}
template <typename T>
inline _LIBCPP_INLINE_VISIBILITY char*
append3(char* buffer, T i) noexcept
{
return append2(append1(buffer, (i) / 100), (i) % 100);
}
template <typename T>
inline _LIBCPP_INLINE_VISIBILITY char*
append4(char* buffer, T i) noexcept
{
return append2(append2(buffer, (i) / 100), (i) % 100);
}
template <typename T>
inline _LIBCPP_INLINE_VISIBILITY char*
append2_no_zeros(char* buffer, T v) noexcept
{
if (v < 10)
return append1(buffer, v);
else
return append2(buffer, v);
}
template <typename T>
inline _LIBCPP_INLINE_VISIBILITY char*
append4_no_zeros(char* buffer, T v) noexcept
{
if (v < 100)
return append2_no_zeros(buffer, v);
else if (v < 1000)
return append3(buffer, v);
else
return append4(buffer, v);
}
template <typename T>
inline _LIBCPP_INLINE_VISIBILITY char*
append8_no_zeros(char* buffer, T v) noexcept
{
if (v < 10000)
{
buffer = append4_no_zeros(buffer, v);
}
else
{
buffer = append4_no_zeros(buffer, v / 10000);
buffer = append4(buffer, v % 10000);
}
return buffer;
}
char*
__u32toa(uint32_t value, char* buffer) noexcept
{
if (value < 100000000)
{
buffer = append8_no_zeros(buffer, value);
}
else
{
// value = aabbbbcccc in decimal
const uint32_t a = value / 100000000; // 1 to 42
value %= 100000000;
buffer = append2_no_zeros(buffer, a);
buffer = append4(buffer, value / 10000);
buffer = append4(buffer, value % 10000);
}
return buffer;
}
char*
__u64toa(uint64_t value, char* buffer) noexcept
{
if (value < 100000000)
{
uint32_t v = static_cast<uint32_t>(value);
buffer = append8_no_zeros(buffer, v);
}
else if (value < 10000000000000000)
{
const uint32_t v0 = static_cast<uint32_t>(value / 100000000);
const uint32_t v1 = static_cast<uint32_t>(value % 100000000);
buffer = append8_no_zeros(buffer, v0);
buffer = append4(buffer, v1 / 10000);
buffer = append4(buffer, v1 % 10000);
}
else
{
const uint32_t a =
static_cast<uint32_t>(value / 10000000000000000); // 1 to 1844
value %= 10000000000000000;
buffer = append4_no_zeros(buffer, a);
const uint32_t v0 = static_cast<uint32_t>(value / 100000000);
const uint32_t v1 = static_cast<uint32_t>(value % 100000000);
buffer = append4(buffer, v0 / 10000);
buffer = append4(buffer, v0 % 10000);
buffer = append4(buffer, v1 / 10000);
buffer = append4(buffer, v1 % 10000);
}
return buffer;
}
} // namespace __itoa
_LIBCPP_END_NAMESPACE_STD
|
