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maths: allow digits10 for 64 bit integers

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This commit is contained in:
Danny Robson 2018-01-01 15:46:29 +11:00
parent 4bd693a799
commit 9fbfba580a
2 changed files with 27 additions and 4 deletions
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27
maths.hpp
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@ -341,11 +341,29 @@ namespace util {
}
//-----------------------------------------------------------------------------
constexpr
unsigned
digits10 (uint32_t v) noexcept
//-------------------------------------------------------------------------
template <
typename NumericT,
typename = std::enable_if_t<
std::is_integral_v<NumericT>,
void
>
>
constexpr auto
digits10 (NumericT v) noexcept
{
// cascading conditionals are faster, but it's super annoying to write
// out for arbitrarily sized types so we use this base case unti
// there's actually a performance reason to use another algorithm.
int tally = 0;
do {
v /= 10;
++tally;
} while (v);
return tally;
/*
return (v >= 1000000000) ? 10 :
(v >= 100000000) ? 9 :
(v >= 10000000) ? 8 :
@ -356,6 +374,7 @@ namespace util {
(v >= 100) ? 3 :
(v >= 10) ? 2 :
1;
*/
}

4
test/maths.cpp
View File

@ -159,6 +159,10 @@ main (void)
tap.expect_eq (util::min (-2, 0, 2), -2, "variadic min");
tap.expect_eq (util::max (-2, 0, 2), 2, "variadic max");
tap.expect_eq (util::digits10( 0), 1, "digits10, 0");
tap.expect_eq (util::digits10( 1), 1, "digits10, 1");
tap.expect_eq (util::digits10(10), 2, "digits10, 10");
tap.expect_eq (util::pow2 (4u), 16u, "pow2");
static const float POS_ZERO = 1.f / numeric_limits<float>::infinity ();