Duckstation/src/common-tests/bitutils_tests.cpp

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2020-04-26 08:33:18 +00:00
#include "common/bitutils.h"
#include "gtest/gtest.h"
#include <type_traits>
template<typename T>
static inline constexpr unsigned ManualCountLeadingZeros(T value)
{
constexpr unsigned BITS = sizeof(T) * 8u;
constexpr T MASK = T(1) << (BITS - 1);
unsigned count = 0;
for (unsigned i = 0; i < BITS && (value & MASK) == 0; i++)
{
count++;
value <<= 1;
}
return count;
}
template<typename T>
static inline constexpr unsigned ManualCountTrailingZeros(T value)
{
constexpr unsigned BITS = sizeof(T) * 8u;
constexpr auto MASK = static_cast<std::make_unsigned_t<T>>(1);
auto u_value = static_cast<std::make_unsigned_t<T>>(value);
unsigned count = 0;
for (unsigned i = 0; i < BITS && (u_value & MASK) != MASK; i++)
{
count++;
u_value >>= 1;
}
return count;
}
TEST(BitUtils, Test8Bit)
{
ASSERT_EQ(CountLeadingZeros(u8(1)), ManualCountLeadingZeros(u8(1)));
ASSERT_EQ(CountLeadingZeros(u8(2)), ManualCountLeadingZeros(u8(2)));
ASSERT_EQ(CountLeadingZeros(u8(4)), ManualCountLeadingZeros(u8(4)));
ASSERT_EQ(CountLeadingZeros(u8(8)), ManualCountLeadingZeros(u8(8)));
ASSERT_EQ(CountLeadingZeros(u8(16)), ManualCountLeadingZeros(u8(16)));
ASSERT_EQ(CountLeadingZeros(u8(32)), ManualCountLeadingZeros(u8(32)));
ASSERT_EQ(CountLeadingZeros(u8(64)), ManualCountLeadingZeros(u8(64)));
ASSERT_EQ(CountLeadingZeros(u8(128)), ManualCountLeadingZeros(u8(128)));
ASSERT_EQ(CountTrailingZeros(u8(1)), ManualCountTrailingZeros(u8(1)));
ASSERT_EQ(CountTrailingZeros(u8(2)), ManualCountTrailingZeros(u8(2)));
ASSERT_EQ(CountTrailingZeros(u8(4)), ManualCountTrailingZeros(u8(4)));
ASSERT_EQ(CountTrailingZeros(u8(8)), ManualCountTrailingZeros(u8(8)));
ASSERT_EQ(CountTrailingZeros(u8(16)), ManualCountTrailingZeros(u8(16)));
ASSERT_EQ(CountTrailingZeros(u8(32)), ManualCountTrailingZeros(u8(32)));
ASSERT_EQ(CountTrailingZeros(u8(64)), ManualCountTrailingZeros(u8(64)));
ASSERT_EQ(CountTrailingZeros(u8(128)), ManualCountTrailingZeros(u8(128)));
}
TEST(BitUtils, Test16Bit)
{
for (u32 i = 1; i < 0x10000; i++)
{
u16 value = Truncate16(i);
ASSERT_EQ(CountLeadingZeros(value), ManualCountLeadingZeros(value));
ASSERT_EQ(CountTrailingZeros(value), ManualCountTrailingZeros(value));
}
}