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Nicer constants.

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This commit is contained in:
Daniel Lemire 2022-11-03 19:40:05 -04:00
parent e958ff4269
commit 3e29bf78c7
1 changed files with 28 additions and 33 deletions
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61
include/fast_float/float_common.h
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@ -220,7 +220,8 @@ constexpr static double powers_of_ten_double[] = {
1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18, 1e19, 1e20, 1e21, 1e22};
constexpr static float powers_of_ten_float[] = {1e0, 1e1, 1e2, 1e3, 1e4, 1e5,
1e6, 1e7, 1e8, 1e9, 1e10};
// used for max_mantissa_double and max_mantissa_float
constexpr uint64_t constant_55555 = 5 * 5 * 5 * 5 * 5;
// Largest integer value v so that (5**index * v) <= 1<<53.
// 0x10000000000000 == 1 << 53
constexpr static uint64_t max_mantissa_double[] = {
@ -229,31 +230,25 @@ constexpr static uint64_t max_mantissa_double[] = {
0x10000000000000 / (5 * 5),
0x10000000000000 / (5 * 5 * 5),
0x10000000000000 / (5 * 5 * 5 * 5),
0x10000000000000 / (5 * 5 * 5 * 5 * 5),
0x10000000000000 / (5 * 5 * 5 * 5 * 5 * 5),
0x10000000000000 / (5 * 5 * 5 * 5 * 5 * 5 * 5),
0x10000000000000 / (5 * 5 * 5 * 5 * 5 * 5 * 5 * 5),
0x10000000000000 / (5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5),
0x10000000000000 / (5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5),
0x10000000000000 / (5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5),
0x10000000000000 / (5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5),
0x10000000000000 / (5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5),
0x10000000000000 / (uint64_t(5) * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5),
0x10000000000000 / (uint64_t(5) * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5),
0x10000000000000 / (uint64_t(5) * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5),
0x10000000000000 / (uint64_t(5) * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5),
0x10000000000000 / (uint64_t(5) * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 *
5),
0x10000000000000 / (uint64_t(5) * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 *
5 * 5),
0x10000000000000 / (uint64_t(5) * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 *
5 * 5 * 5),
0x10000000000000 / (uint64_t(5) * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 *
5 * 5 * 5 * 5),
0x10000000000000 / (uint64_t(5) * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 *
5 * 5 * 5 * 5 * 5),
0x10000000000000 / (uint64_t(5) * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 *
5 * 5 * 5 * 5 * 5 * 5)};
0x10000000000000 / (constant_55555),
0x10000000000000 / (constant_55555 * 5),
0x10000000000000 / (constant_55555 * 5 * 5),
0x10000000000000 / (constant_55555 * 5 * 5 * 5),
0x10000000000000 / (constant_55555 * 5 * 5 * 5 * 5),
0x10000000000000 / (constant_55555 * constant_55555),
0x10000000000000 / (constant_55555 * constant_55555 * 5),
0x10000000000000 / (constant_55555 * constant_55555 * 5 * 5),
0x10000000000000 / (constant_55555 * constant_55555 * 5 * 5 * 5),
0x10000000000000 / (constant_5555constant_55555 * constant_55555),
0x10000000000000 / (constant_5555constant_55555 * constant_55555 * 5),
0x10000000000000 / (constant_5555constant_55555 * constant_55555 * 5 * 5),
0x10000000000000 / (constant_5555constant_55555 * constant_55555 * 5 * 5 * 5),
0x10000000000000 / (constant_5555constant_55555 * constant_55555 * 5 * 5 * 5 * 5),
0x10000000000000 / (constant_5555constant_55555 * constant_55555 * constant_55555),
0x10000000000000 / (constant_5555constant_55555 * constant_55555 * constant_55555 * 5),
0x10000000000000 / (constant_5555constant_55555 * constant_55555 * constant_55555 * 5 * 5),
0x10000000000000 / (constant_5555constant_55555 * constant_55555 * constant_55555 * 5 * 5 * 5),
0x10000000000000 / (constant_5555constant_55555 * constant_55555 * constant_55555 * 5 * 5 * 5 * 5)};
// Largest integer value v so that (5**index * v) <= 1<<24.
// 0x1000000 == 1<<24
constexpr static uint64_t max_mantissa_float[] = {
@ -262,13 +257,13 @@ constexpr static uint64_t max_mantissa_double[] = {
0x1000000 / (5 * 5),
0x1000000 / (5 * 5 * 5),
0x1000000 / (5 * 5 * 5 * 5),
0x1000000 / (5 * 5 * 5 * 5 * 5),
0x1000000 / (5 * 5 * 5 * 5 * 5 * 5),
0x1000000 / (5 * 5 * 5 * 5 * 5 * 5 * 5),
0x1000000 / (5 * 5 * 5 * 5 * 5 * 5 * 5 * 5),
0x1000000 / (5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5),
0x1000000 / (5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5),
0x1000000 / (5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5)};
0x1000000 / (constant_55555),
0x1000000 / (constant_55555 * 5),
0x1000000 / (constant_55555 * 5 * 5),
0x1000000 / (constant_55555 * 5 * 5 * 5),
0x1000000 / (constant_55555 * 5 * 5 * 5 * 5),
0x1000000 / (constant_55555 * constant_55555),
0x1000000 / (constant_55555 * constant_55555 * 5)};
template <typename T> struct binary_format {
using equiv_uint = typename std::conditional<sizeof(T) == 4, uint32_t, uint64_t>::type;