dynarmic/src/common/math_util.cpp

31 lines
773 B
C++

/* This file is part of the dynarmic project.
* Copyright (c) 2018 MerryMage
* This software may be used and distributed according to the terms of the GNU
* General Public License version 2 or any later version.
*/
#include <array>
#include "common/math_util.h"
namespace Dynarmic::Common {
u8 RecipEstimate(u64 a) {
using LUT = std::array<u8, 256>;
static constexpr u64 lut_offset = 256;
static const LUT lut = [] {
LUT result{};
for (u64 i = 0; i < result.size(); i++) {
u64 a = i + lut_offset;
a = a * 2 + 1;
u64 b = (1u << 19) / a;
result[i] = static_cast<u8>((b + 1) / 2);
}
return result;
}();
return lut[a - lut_offset];
}
} // namespace Dynarmic::Common