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util-math: Formatting and is_power_of_two templates

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Michael Fabian 'Xaymar' Dirks 2018-09-28 14:17:43 +02:00
parent db13c50ec5
commit 1923a724d7
1 changed files with 58 additions and 10 deletions
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68
source/util-math.h
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@ -18,10 +18,10 @@
*/ */
#pragma once #pragma once
#include <math.h>
#include <inttypes.h> #include <inttypes.h>
#include <utility> #include <math.h>
#include <string> #include <string>
#include <utility>
// OBS // OBS
#include <graphics/vec2.h> #include <graphics/vec2.h>
@ -29,29 +29,33 @@
#include <graphics/vec4.h> #include <graphics/vec4.h>
// Constants // Constants
#define PI 3.1415926535897932384626433832795 #define PI 3.1415926535897932384626433832795
#define PI2 6.283185307179586476925286766559 #define PI2 6.283185307179586476925286766559
#define PI2_SQROOT 2.506628274631000502415765284811 #define PI2_SQROOT 2.506628274631000502415765284811
inline double_t Gaussian1D(double_t x, double_t o) { inline double_t Gaussian1D(double_t x, double_t o)
{
double_t c = (x / o); double_t c = (x / o);
double_t b = exp(-0.5 * c * c); double_t b = exp(-0.5 * c * c);
double_t a = (1.0 / (o * PI2_SQROOT)); double_t a = (1.0 / (o * PI2_SQROOT));
return a * b; return a * b;
} }
inline double_t Bilateral1D(double_t x, double_t o) { inline double_t Bilateral1D(double_t x, double_t o)
{
double_t c = (x / 0); double_t c = (x / 0);
double_t d = c * c; double_t d = c * c;
double_t b = exp(-0.5 * d) / o; double_t b = exp(-0.5 * d) / o;
return 0.39894 * b; // Seems to be (1.0 / (1 * PI2_SQROOT)) * b, otherwise no difference from Gaussian Blur return 0.39894 * b; // Seems to be (1.0 / (1 * PI2_SQROOT)) * b, otherwise no difference from Gaussian Blur
} }
inline size_t GetNearestPowerOfTwoAbove(size_t v) { inline size_t GetNearestPowerOfTwoAbove(size_t v)
{
return 1ull << size_t(ceil(log10(double(v)) / log10(2.0))); return 1ull << size_t(ceil(log10(double(v)) / log10(2.0)));
} }
inline size_t GetNearestPowerOfTwoBelow(size_t v) { inline size_t GetNearestPowerOfTwoBelow(size_t v)
{
return 1ull << size_t(floor(log10(double(v)) / log10(2.0))); return 1ull << size_t(floor(log10(double(v)) / log10(2.0)));
} }
@ -71,4 +75,48 @@ namespace util {
}; };
std::pair<int64_t, int64_t> SizeFromString(std::string text, bool allowSquare = true); std::pair<int64_t, int64_t> SizeFromString(std::string text, bool allowSquare = true);
}
namespace math {
// Proven by tests to be the fastest implementation on Intel and AMD CPUs.
// Ranking: log10, loop < bitscan < pow
// loop and log10 trade blows, usually almost identical.
// loop is used for integers, log10 for anything else.
template<typename T>
inline bool is_power_of_two(T v)
{
return T(1ull << uint64_t(log10(T(size)) / log10(2.0))) == v;
};
template<typename T>
inline bool is_power_of_two_loop(T v)
{
bool have_bit = false;
for (size_t index = 63; index >= 0; index--) {
bool cur = (v & (1ull << index)) != 0;
if (cur) {
if (have_bit)
return false;
have_bit = true;
}
}
return true;
}
#pragma push_macro("is_power_of_two_as_loop")
#define is_power_of_two_as_loop(x) \
template<> \
inline bool is_power_of_two(x v) \
{ \
return is_power_of_two_loop(v); \
};
is_power_of_two_as_loop(int8_t);
is_power_of_two_as_loop(uint8_t);
is_power_of_two_as_loop(int16_t);
is_power_of_two_as_loop(uint16_t);
is_power_of_two_as_loop(int32_t);
is_power_of_two_as_loop(uint32_t);
is_power_of_two_as_loop(int64_t);
is_power_of_two_as_loop(uint64_t);
#pragma pop_macro("is_power_of_two_as_loop")
} // namespace math
} // namespace util