120 lines
3.4 KiB
C++
120 lines
3.4 KiB
C++
// SPDX-FileCopyrightText: Copyright 2019 yuzu Emulator Project
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// SPDX-License-Identifier: GPL-2.0-or-later
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#pragma once
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#include <utility>
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#ifdef _MSC_VER
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#include <intrin.h>
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#pragma intrinsic(__umulh)
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#pragma intrinsic(_umul128)
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#pragma intrinsic(_udiv128)
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#else
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#include <cstring>
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#endif
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#include "common/common_types.h"
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namespace Common {
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// This function multiplies 2 u64 values and divides it by a u64 value.
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[[nodiscard]] static inline u64 MultiplyAndDivide64(u64 a, u64 b, u64 d) {
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#ifdef _MSC_VER
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u128 r{};
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r[0] = _umul128(a, b, &r[1]);
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u64 remainder;
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#if _MSC_VER < 1923
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return udiv128(r[1], r[0], d, &remainder);
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#else
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return _udiv128(r[1], r[0], d, &remainder);
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#endif
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#else
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const u64 diva = a / d;
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const u64 moda = a % d;
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const u64 divb = b / d;
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const u64 modb = b % d;
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return diva * b + moda * divb + moda * modb / d;
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#endif
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}
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// This function multiplies 2 u64 values and produces a u128 value;
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[[nodiscard]] static inline u128 Multiply64Into128(u64 a, u64 b) {
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u128 result;
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#ifdef _MSC_VER
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result[0] = _umul128(a, b, &result[1]);
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#else
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unsigned __int128 tmp = a;
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tmp *= b;
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std::memcpy(&result, &tmp, sizeof(u128));
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#endif
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return result;
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}
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[[nodiscard]] static inline u64 GetFixedPoint64Factor(u64 numerator, u64 divisor) {
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#ifdef __SIZEOF_INT128__
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const auto base = static_cast<unsigned __int128>(numerator) << 64ULL;
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return static_cast<u64>(base / divisor);
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#elif defined(_M_X64) || defined(_M_ARM64)
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std::array<u64, 2> r = {0, numerator};
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u64 remainder;
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#if _MSC_VER < 1923
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return udiv128(r[1], r[0], divisor, &remainder);
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#else
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return _udiv128(r[1], r[0], divisor, &remainder);
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#endif
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#else
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// This one is bit more inaccurate.
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return MultiplyAndDivide64(std::numeric_limits<u64>::max(), numerator, divisor);
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#endif
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}
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[[nodiscard]] static inline u64 MultiplyHigh(u64 a, u64 b) {
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#ifdef __SIZEOF_INT128__
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return (static_cast<unsigned __int128>(a) * static_cast<unsigned __int128>(b)) >> 64;
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#elif defined(_M_X64) || defined(_M_ARM64)
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return __umulh(a, b); // MSVC
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#else
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// Generic fallback
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const u64 a_lo = u32(a);
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const u64 a_hi = a >> 32;
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const u64 b_lo = u32(b);
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const u64 b_hi = b >> 32;
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const u64 a_x_b_hi = a_hi * b_hi;
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const u64 a_x_b_mid = a_hi * b_lo;
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const u64 b_x_a_mid = b_hi * a_lo;
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const u64 a_x_b_lo = a_lo * b_lo;
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const u64 carry_bit = (static_cast<u64>(static_cast<u32>(a_x_b_mid)) +
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static_cast<u64>(static_cast<u32>(b_x_a_mid)) + (a_x_b_lo >> 32)) >>
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32;
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const u64 multhi = a_x_b_hi + (a_x_b_mid >> 32) + (b_x_a_mid >> 32) + carry_bit;
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return multhi;
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#endif
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}
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// This function divides a u128 by a u32 value and produces two u64 values:
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// the result of division and the remainder
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[[nodiscard]] static inline std::pair<u64, u64> Divide128On32(u128 dividend, u32 divisor) {
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u64 remainder = dividend[0] % divisor;
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u64 accum = dividend[0] / divisor;
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if (dividend[1] == 0)
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return {accum, remainder};
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// We ignore dividend[1] / divisor as that overflows
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const u64 first_segment = (dividend[1] % divisor) << 32;
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accum += (first_segment / divisor) << 32;
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const u64 second_segment = (first_segment % divisor) << 32;
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accum += (second_segment / divisor);
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remainder += second_segment % divisor;
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if (remainder >= divisor) {
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accum++;
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remainder -= divisor;
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}
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return {accum, remainder};
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}
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} // namespace Common
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