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duckstation
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BitUtils: Make Count{Leading,Trailing}Zeros UB for value==0

This commit is contained in:
Connor McLaughlin 2020-04-26 18:32:23 +10:00
parent 38b075c014
commit 5671fde1ae
3 changed files with 19 additions and 21 deletions
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1
README.md
View File

@ -27,6 +27,7 @@ Other features include:
- Direct booting of homebrew executables
- Direct loading of Portable Sound Format (psf) files
- Digital and analog controllers for input (rumble is forwarded to host)
- Namco GunCon lightgun support (simulated with mouse)
- Qt and SDL frontends for desktop
- Automatic content scanning - game titles/regions are provided by redump.org

36
src/common/bitutils.h
View File

@ -5,6 +5,7 @@
#include <intrin.h>
#endif
/// Returns the number of zero bits before the first set bit, going MSB->LSB.
template<typename T>
ALWAYS_INLINE unsigned CountLeadingZeros(T value)
{
@ -12,27 +13,26 @@ ALWAYS_INLINE unsigned CountLeadingZeros(T value)
if constexpr (sizeof(value) >= sizeof(u64))
{
unsigned long index;
return _BitScanReverse64(&index, ZeroExtend64(value)) ? static_cast<unsigned>(index) : 0;
_BitScanReverse64(&index, ZeroExtend64(value));
return static_cast<unsigned>(index) ^ static_cast<unsigned>((sizeof(value) * 8u) - 1u);
}
else
{
unsigned long index;
return _BitScanReverse(&index, ZeroExtend32(value)) ? static_cast<unsigned>(index) : 0;
_BitScanReverse(&index, ZeroExtend32(value));
return static_cast<unsigned>(index) ^ static_cast<unsigned>((sizeof(value) * 8u) - 1u);
}
#else
if constexpr (sizeof(value) >= sizeof(u64))
{
const unsigned bits = static_cast<unsigned>(__builtin_clzl(ZeroExtend64(value)));
return (value != 0) ? static_cast<unsigned>(bits) : 0;
}
return static_cast<unsigned>(__builtin_clzl(ZeroExtend64(value)));
else if constexpr (sizeof(value) == sizeof(u32))
return static_cast<unsigned>(__builtin_clz(ZeroExtend32(value)));
else
{
const unsigned bits = static_cast<unsigned>(__builtin_clz(ZeroExtend32(value)));
return (value != 0) ? static_cast<unsigned>(bits) : 0;
}
return static_cast<unsigned>(__builtin_clz(ZeroExtend32(value))) & static_cast<unsigned>((sizeof(value) * 8u) - 1u);
#endif
}
/// Returns the number of zero bits before the first set bit, going LSB->MSB.
template<typename T>
ALWAYS_INLINE unsigned CountTrailingZeros(T value)
{
@ -40,23 +40,19 @@ ALWAYS_INLINE unsigned CountTrailingZeros(T value)
if constexpr (sizeof(value) >= sizeof(u64))
{
unsigned long index;
return _BitScanForward64(&index, ZeroExtend64(value)) ? static_cast<unsigned>(index) : 0;
_BitScanForward64(&index, ZeroExtend64(value));
return index;
}
else
{
unsigned long index;
return _BitScanForward(&index, ZeroExtend32(value)) ? static_cast<unsigned>(index) : 0;
_BitScanForward(&index, ZeroExtend32(value));
return index;
}
#else
if constexpr (sizeof(value) >= sizeof(u64))
{
const unsigned bits = static_cast<unsigned>(__builtin_ctzl(ZeroExtend64(value)));
return (value != 0) ? static_cast<unsigned>(bits) : 0;
}
return static_cast<unsigned>(__builtin_ctzl(ZeroExtend64(value)));
else
{
const unsigned bits = static_cast<unsigned>(__builtin_ctz(ZeroExtend32(value)));
return (value != 0) ? static_cast<unsigned>(bits) : 0;
}
return static_cast<unsigned>(__builtin_ctz(ZeroExtend32(value)));
#endif
}

3
src/duckstation-qt/inputbindingwidgets.cpp
View File

@ -168,7 +168,8 @@ bool InputButtonBindingWidget::eventFilter(QObject* watched, QEvent* event)
}
else if (event_type == QEvent::MouseButtonRelease)
{
const u32 button_index = CountTrailingZeros(static_cast<u32>(static_cast<const QMouseEvent*>(event)->button()));
const u32 button_mask = static_cast<u32>(static_cast<const QMouseEvent*>(event)->button());
const u32 button_index = (button_mask == 0u) ? 0 : CountTrailingZeros(button_mask);
m_new_binding_value = QStringLiteral("Mouse/Button%1").arg(button_index + 1);
setNewBinding();
stopListeningForInput();