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[Enhancement] Refactor functions in int_exp by templates (#9939)

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This commit is contained in:
Twice
2022-06-04 11:53:31 +08:00
committed by GitHub
parent da33a48f39
commit f49284036e
1 changed files with 34 additions and 88 deletions
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122
be/src/vec/common/int_exp.h
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@ -22,6 +22,34 @@
#include <cstdint>
#include <limits>
#include <utility>
namespace exp_details {
// compile-time exp(v, n) by linear recursion
template <typename T, T v, std::size_t n>
constexpr inline const T exp = T(v) * exp<T, v, n - 1>;
template <typename T, T v>
constexpr inline const T exp<T, v, 0> = 1;
// compile-time exponentiation table { exp(v, I) ... }
template <typename T, T v, std::size_t... I>
constexpr inline const T exp_table[] = {exp<T, v, I>...};
// get value from compile-time exponentiation table by a (maybe) runtime offset
template <typename T, T v, std::size_t... I>
constexpr T get_exp_helper(std::size_t x, std::index_sequence<I...>) {
return exp_table<T, v, I...>[x];
}
// get_exp_helper with table { exp(v, 0), exp(v, 1) ... exp(v, N - 1) }
template <typename T, T v, std::size_t N>
constexpr T get_exp(std::size_t x) {
return get_exp_helper<T, v>(x, std::make_index_sequence<N> {});
}
} // namespace exp_details
/// On overlow, the function returns unspecified value.
@ -33,103 +61,21 @@ inline uint64_t int_exp10(int x) {
if (x < 0) return 0;
if (x > 19) return std::numeric_limits<uint64_t>::max();
static const uint64_t table[20] = {1ULL,
10ULL,
100ULL,
1000ULL,
10000ULL,
100000ULL,
1000000ULL,
10000000ULL,
100000000ULL,
1000000000ULL,
10000000000ULL,
100000000000ULL,
1000000000000ULL,
10000000000000ULL,
100000000000000ULL,
1000000000000000ULL,
10000000000000000ULL,
100000000000000000ULL,
1000000000000000000ULL,
10000000000000000000ULL};
return table[x];
return exp_details::get_exp<uint64_t, 10, 20>(x);
}
namespace common {
inline int exp10_i32(int x) {
static const int values[] = {1, 10, 100, 1000, 10000,
100000, 1000000, 10000000, 100000000, 1000000000};
return values[x];
inline std::int32_t exp10_i32(int x) {
return exp_details::get_exp<std::int32_t, 10, 10>(x);
}
inline int64_t exp10_i64(int x) {
static const int64_t values[] = {1ll,
10ll,
100ll,
1000ll,
10000ll,
100000ll,
1000000ll,
10000000ll,
100000000ll,
1000000000ll,
10000000000ll,
100000000000ll,
1000000000000ll,
10000000000000ll,
100000000000000ll,
1000000000000000ll,
10000000000000000ll,
100000000000000000ll,
1000000000000000000ll};
return values[x];
inline std::int64_t exp10_i64(int x) {
return exp_details::get_exp<std::int64_t, 10, 19>(x);
}
inline __int128 exp10_i128(int x) {
static const __int128 values[] = {
static_cast<__int128>(1ll),
static_cast<__int128>(10ll),
static_cast<__int128>(100ll),
static_cast<__int128>(1000ll),
static_cast<__int128>(10000ll),
static_cast<__int128>(100000ll),
static_cast<__int128>(1000000ll),
static_cast<__int128>(10000000ll),
static_cast<__int128>(100000000ll),
static_cast<__int128>(1000000000ll),
static_cast<__int128>(10000000000ll),
static_cast<__int128>(100000000000ll),
static_cast<__int128>(1000000000000ll),
static_cast<__int128>(10000000000000ll),
static_cast<__int128>(100000000000000ll),
static_cast<__int128>(1000000000000000ll),
static_cast<__int128>(10000000000000000ll),
static_cast<__int128>(100000000000000000ll),
static_cast<__int128>(1000000000000000000ll),
static_cast<__int128>(1000000000000000000ll) * 10ll,
static_cast<__int128>(1000000000000000000ll) * 100ll,
static_cast<__int128>(1000000000000000000ll) * 1000ll,
static_cast<__int128>(1000000000000000000ll) * 10000ll,
static_cast<__int128>(1000000000000000000ll) * 100000ll,
static_cast<__int128>(1000000000000000000ll) * 1000000ll,
static_cast<__int128>(1000000000000000000ll) * 10000000ll,
static_cast<__int128>(1000000000000000000ll) * 100000000ll,
static_cast<__int128>(1000000000000000000ll) * 1000000000ll,
static_cast<__int128>(1000000000000000000ll) * 10000000000ll,
static_cast<__int128>(1000000000000000000ll) * 100000000000ll,
static_cast<__int128>(1000000000000000000ll) * 1000000000000ll,
static_cast<__int128>(1000000000000000000ll) * 10000000000000ll,
static_cast<__int128>(1000000000000000000ll) * 100000000000000ll,
static_cast<__int128>(1000000000000000000ll) * 1000000000000000ll,
static_cast<__int128>(1000000000000000000ll) * 10000000000000000ll,
static_cast<__int128>(1000000000000000000ll) * 100000000000000000ll,
static_cast<__int128>(1000000000000000000ll) * 100000000000000000ll * 10ll,
static_cast<__int128>(1000000000000000000ll) * 100000000000000000ll * 100ll,
static_cast<__int128>(1000000000000000000ll) * 100000000000000000ll * 1000ll};
return values[x];
return exp_details::get_exp<__int128, 10, 39>(x);
}
} // namespace common