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#pragma once
#include <util/generic/cast.h>
#include <util/generic/ylimits.h>
#include <util/system/hi_lo.h>
#include <cmath>
#include <cfloat>
#include <limits>
#include <algorithm>
#include <cassert>
namespace NPackedFloat {
/*
Exponent Mantissa zero Mantissa non-zero Equation
0x00 zero denormal (-1)^sign * 2^-126 * 0.mantissa
0x01–0xfe normalized value (-1)^sign * 2^(exponent - 127) * 1.mantissa
0xff infinity NaN
* */
//fast 16 bit floats by melkov
template <ui8 SIGNED>
struct float16 {
private:
typedef float16<SIGNED> self;
public:
ui16 val;
explicit float16(ui16 v = 0)
: val(v)
{
}
self& operator=(float t) {
assert(SIGNED == 1 || SIGNED == 0 && t >= 0.);
val = BitCast<ui32>(t) >> (15 + SIGNED);
return *this;
}
operator float() const {
return BitCast<float>((ui32)val << (15 + SIGNED));
}
static self New(float v) {
self f;
return f = v;
}
static self denorm_min() {
return self(0x0001);
}
static self min() {
return self(SIGNED ? 0x0080 : 0x0100);
}
static self max() {
return self(SIGNED ? 0x7f7f : 0xfeff);
}
};
//fast 8 bit floats
template <ui8 SIGNED, ui8 DENORM = 0>
struct float8 {
private:
typedef float8<SIGNED, DENORM> self;
enum {
FMinExp = SIGNED ? 0x7c : 0x78,
FMaxExp = SIGNED ? 0x83 : 0x87,
MaxExp = SIGNED ? 0x70 : 0xf0,
};
public:
ui8 val;
explicit float8(ui8 v = 0)
: val(v)
{
}
self& operator=(float t) {
assert(SIGNED == 1 || SIGNED == 0 && t >= 0.);
ui16 hi16 = Hi16(t);
ui8 sign = SIGNED ? Hi8(hi16) & 0x80 : 0;
hi16 <<= 1;
ui8 fexp = Hi8(hi16);
ui8 exp;
ui8 frac = (Lo8(hi16) & 0xf0) >> 4;
if (fexp <= FMinExp) {
exp = 0;
frac = DENORM ? ((ui8)(0x10 | frac) >> std::min<int>((FMinExp - fexp + 1), 8)) : 0;
} else if (fexp > FMaxExp) {
exp = MaxExp;
frac = 0x0f;
} else {
exp = (fexp - FMinExp) << 4;
}
val = sign | exp | frac;
return *this;
}
operator float() const {
ui32 v = 0;
v |= SIGNED ? (val & 0x80) << 24 : 0;
ui8 frac = val & 0x0f;
ui8 exp = val & MaxExp;
if (exp) {
v |= ((exp >> 4) + FMinExp) << 23 | frac << 19;
} else if (DENORM && val & 0x0f) {
while (!(frac & 0x10)) {
frac <<= 1;
++exp;
}
v |= (FMinExp - exp + 1) << 23 | (frac & 0x0f) << 19;
} else
v |= 0;
return BitCast<float>(v);
}
static self New(float v) {
self f;
return f = v;
}
static self denorm_min() {
return self(0x01);
}
static self min() {
return self(0x10);
}
static self max() {
return self(SIGNED ? 0x7f : 0xff);
}
};
}
using f64 = double;
using f32 = float;
static_assert(sizeof(f32) == 4, "expect sizeof(f32) == 4");
static_assert(sizeof(f64) == 8, "expect sizeof(f64) == 8");
using f16 = NPackedFloat::float16<1>;
using uf16 = NPackedFloat::float16<0>;
using f8 = NPackedFloat::float8<1>;
using uf8 = NPackedFloat::float8<0>;
using f8d = NPackedFloat::float8<1, 1>;
using uf8d = NPackedFloat::float8<0, 1>;
// [0,1) value in 1/255s.
using frac8 = ui8;
using frac16 = ui16;
template <class T>
inline constexpr T Float2Frac(float fac) {
return T(fac * float(Max<T>()));
}
template <class T>
inline constexpr T Float2FracR(float fac) {
float v = fac * float(Max<T>());
return T(v + 0.5f);
}
template <class T>
inline constexpr float Frac2Float(T pf) {
constexpr float multiplier = float(1.0 / Max<T>());
return pf * multiplier;
}
class TUi82FloatMapping {
private:
float Mapping[Max<ui8>() + 1] = {};
public:
constexpr TUi82FloatMapping() noexcept {
for (ui32 i = 0; i < Y_ARRAY_SIZE(Mapping); ++i) {
Mapping[i] = static_cast<float>(i) / Max<ui8>();
}
}
inline float operator [] (ui8 index) const {
return Mapping[index];
}
};
constexpr TUi82FloatMapping Ui82FloatMapping{};
template <>
inline float Frac2Float(ui8 pf) {
return Ui82FloatMapping[pf];
}
// Probably you don't want to use it, since sizeof(float) == sizeof(ui32)
template <>
inline float Frac2Float(ui32 pf) = delete;
template <class T>
inline float FracOrFloatToFloat(T t) {
return Frac2Float(t);
}
template <>
inline float FracOrFloatToFloat<float>(float t) {
return t;
}
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