mirror of
https://github.com/RetroDECK/Duckstation.git
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69 lines
2.2 KiB
C++
69 lines
2.2 KiB
C++
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#include "common/bitutils.h"
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#include "gtest/gtest.h"
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#include <type_traits>
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template<typename T>
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static inline constexpr unsigned ManualCountLeadingZeros(T value)
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{
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constexpr unsigned BITS = sizeof(T) * 8u;
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constexpr T MASK = T(1) << (BITS - 1);
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unsigned count = 0;
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for (unsigned i = 0; i < BITS && (value & MASK) == 0; i++)
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{
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count++;
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value <<= 1;
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}
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return count;
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}
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template<typename T>
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static inline constexpr unsigned ManualCountTrailingZeros(T value)
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{
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constexpr unsigned BITS = sizeof(T) * 8u;
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constexpr auto MASK = static_cast<std::make_unsigned_t<T>>(1);
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auto u_value = static_cast<std::make_unsigned_t<T>>(value);
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unsigned count = 0;
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for (unsigned i = 0; i < BITS && (u_value & MASK) != MASK; i++)
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{
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count++;
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u_value >>= 1;
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}
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return count;
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}
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TEST(BitUtils, Test8Bit)
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{
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ASSERT_EQ(CountLeadingZeros(u8(1)), ManualCountLeadingZeros(u8(1)));
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ASSERT_EQ(CountLeadingZeros(u8(2)), ManualCountLeadingZeros(u8(2)));
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ASSERT_EQ(CountLeadingZeros(u8(4)), ManualCountLeadingZeros(u8(4)));
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ASSERT_EQ(CountLeadingZeros(u8(8)), ManualCountLeadingZeros(u8(8)));
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ASSERT_EQ(CountLeadingZeros(u8(16)), ManualCountLeadingZeros(u8(16)));
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ASSERT_EQ(CountLeadingZeros(u8(32)), ManualCountLeadingZeros(u8(32)));
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ASSERT_EQ(CountLeadingZeros(u8(64)), ManualCountLeadingZeros(u8(64)));
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ASSERT_EQ(CountLeadingZeros(u8(128)), ManualCountLeadingZeros(u8(128)));
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ASSERT_EQ(CountTrailingZeros(u8(1)), ManualCountTrailingZeros(u8(1)));
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ASSERT_EQ(CountTrailingZeros(u8(2)), ManualCountTrailingZeros(u8(2)));
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ASSERT_EQ(CountTrailingZeros(u8(4)), ManualCountTrailingZeros(u8(4)));
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ASSERT_EQ(CountTrailingZeros(u8(8)), ManualCountTrailingZeros(u8(8)));
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ASSERT_EQ(CountTrailingZeros(u8(16)), ManualCountTrailingZeros(u8(16)));
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ASSERT_EQ(CountTrailingZeros(u8(32)), ManualCountTrailingZeros(u8(32)));
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ASSERT_EQ(CountTrailingZeros(u8(64)), ManualCountTrailingZeros(u8(64)));
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ASSERT_EQ(CountTrailingZeros(u8(128)), ManualCountTrailingZeros(u8(128)));
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}
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TEST(BitUtils, Test16Bit)
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{
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for (u32 i = 1; i < 0x10000; i++)
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{
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u16 value = Truncate16(i);
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ASSERT_EQ(CountLeadingZeros(value), ManualCountLeadingZeros(value));
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ASSERT_EQ(CountTrailingZeros(value), ManualCountTrailingZeros(value));
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}
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}
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