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JitCommon: Signed 32-bit division magic constants

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Add a function to calculate the magic constants required to optimize
signed 32-bit division.

Since this optimization is not exclusive to any particular architecture,
JitCommon seemed like a good place to put this.
This commit is contained in:
Sintendo
2021-03-03 23:48:28 +01:00
parent c9adc60d73
commit 5bb8798df6
6 changed files with 121 additions and 0 deletions
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33
Source/UnitTests/DivUtilsTest.cpp Normal file
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// Copyright 2021 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
#include <gtest/gtest.h>
#include "Core/PowerPC/JitCommon/DivUtils.h"
using namespace JitCommon;
TEST(DivUtils, Signed)
{
Magic m3 = SignedDivisionConstants(3);
Magic m5 = SignedDivisionConstants(5);
Magic m7 = SignedDivisionConstants(7);
Magic minus3 = SignedDivisionConstants(-3);
Magic minus5 = SignedDivisionConstants(-5);
Magic minus7 = SignedDivisionConstants(-7);
EXPECT_EQ(0x55555556, m3.multiplier);
EXPECT_EQ(0, m3.shift);
EXPECT_EQ(0x66666667, m5.multiplier);
EXPECT_EQ(1, m5.shift);
EXPECT_EQ(-0x6DB6DB6D, m7.multiplier);
EXPECT_EQ(2, m7.shift);
EXPECT_EQ(-0x55555556, minus3.multiplier);
EXPECT_EQ(0, minus3.shift);
EXPECT_EQ(-0x66666667, minus5.multiplier);
EXPECT_EQ(1, minus5.shift);
EXPECT_EQ(0x6DB6DB6D, minus7.multiplier);
EXPECT_EQ(2, minus7.shift);
}