1 files changed, 189 insertions, 0 deletions
diff --git a/Runtime/Utilities/BitUtility.h b/Runtime/Utilities/BitUtility.h
new file mode 100644
index 0000000..774d6e0
--- /dev/null
+++ b/Runtime/Utilities/BitUtility.h
@@ -0,0 +1,189 @@
+#ifndef BITUTILITY_H
+#define BITUTILITY_H
+
+#include <limits.h>
+
+// index of the most significant bit in the mask
+
+const char gHighestBitLut[] = {-1,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3};
+
+inline int HighestBit(UInt32 mask)
+{
+#ifdef SN_TARGET_PS3
+	return 31 - __cntlzw(mask);
+#else
+	int base = 0;
+
+	if ( mask & 0xffff0000 )
+	{
+		base = 16;
+		mask >>= 16;
+	}
+	if ( mask & 0x0000ff00 )
+	{
+		base += 8;
+		mask >>= 8;
+	}
+	if ( mask & 0x000000f0 )
+	{
+		base += 4;
+		mask >>= 4;
+	}
+
+	return base + gHighestBitLut[ mask ];
+#endif
+}
+
+
+// index of the least significant bit in the mask
+
+const char gLowestBitLut[] = {-1,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0};
+inline int LowestBit(UInt32 mask)
+{
+	AssertIf (mask == 0);
+	
+	int base = 0;
+
+	if ( !(mask & 0xffff) )
+	{
+		base = 16;
+		mask >>= 16;
+	}
+	if ( !(mask & 0x00ff) )
+	{
+		base += 8;
+		mask >>= 8;
+	}
+	if ( !(mask & 0x000f) )
+	{
+		base += 4;
+		mask >>= 4;
+	}
+
+	return base + gLowestBitLut[ mask & 15 ];
+}
+
+// can be optimized later
+inline int AnyBitFromMask (UInt32 mask)
+{
+	return HighestBit (mask);
+}
+
+// index of the first consecutiveBitCount enabled bits
+// -1 if not available
+inline int LowestBitConsecutive (UInt32 bitMask, int consecutiveBitCount)
+{
+    UInt32 tempBitMask = bitMask;
+    int i;
+    for (i=1;i<consecutiveBitCount;i++)
+        tempBitMask &= bitMask >> i;
+    
+    if (!tempBitMask)
+        return -1;
+    else
+        return LowestBit (tempBitMask);
+}
+/*int LowestBitConsecutive ( u_int value, u_int consecutiveBitCount )
+{
+	u_int mask = (1 << consecutiveBitCount) - 1;
+	u_int notValue = value ^ 0xffffffff;
+	u_int workingMask = mask;
+	u_int prevMask = 0;
+	int match = notValue & workingMask;
+	u_int shift = 1;
+	while ( (match != 0) && (prevMask < workingMask) )
+	{
+		shift = 2*u_int(match & -match);
+		prevMask = workingMask;
+		workingMask = mask * shift;
+		match = notValue & workingMask;
+	}
+	if ( prevMask < workingMask )
+	{
+		return LowestBit( shift );
+	}
+	else
+	{
+		return -1;
+	}
+}*/
+
+// number of set bits in the 32 bit mask
+inline int BitsInMask (UInt32 v)
+{
+	// From http://www-graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
+	// This variant about 30% faster on 360 than what was here before.
+	v = v - ((v >> 1) & 0x55555555);
+	v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
+	return ((v + (v >> 4) & 0xF0F0F0F) * 0x1010101) >> 24;
+}
+
+// number of set bits in the 64 bit mask
+inline int BitsInMask64 (UInt64 v)
+{
+	// From http://www-graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
+	v = v - ((v >> 1) & (UInt64)~(UInt64)0/3);
+	v = (v & (UInt64)~(UInt64)0/15*3) + ((v >> 2) & (UInt64)~(UInt64)0/15*3);
+	v = (v + (v >> 4)) & (UInt64)~(UInt64)0/255*15;
+	return (UInt64)(v * ((UInt64)~(UInt64)0/255)) >> (sizeof(UInt64) - 1) * CHAR_BIT;
+}
+
+// reverse bit order
+inline void ReverseBits(UInt32& mask)
+{
+	mask = ((mask >>  1) & 0x55555555) | ((mask <<  1) & 0xaaaaaaaa);
+	mask = ((mask >>  2) & 0x33333333) | ((mask <<  2) & 0xcccccccc);
+	mask = ((mask >>  4) & 0x0f0f0f0f) | ((mask <<  4) & 0xf0f0f0f0);
+	mask = ((mask >>  8) & 0x00ff00ff) | ((mask <<  8) & 0xff00ff00);
+	mask = ((mask >> 16) & 0x0000ffff) | ((mask << 16) & 0xffff0000) ;
+}
+
+// is value a power-of-two
+inline bool IsPowerOfTwo(UInt32 mask)
+{
+	return (mask & (mask-1)) == 0;
+}
+
+// return the next power-of-two of a 32bit number
+inline UInt32 NextPowerOfTwo(UInt32 v)
+{
+	v -= 1;
+	v |= v >> 16;
+	v |= v >> 8;
+	v |= v >> 4;
+	v |= v >> 2;
+	v |= v >> 1;
+	return v + 1;
+}
+
+// return the closest power-of-two of a 32bit number
+inline UInt32 ClosestPowerOfTwo(UInt32 v)
+{
+	UInt32 nextPower = NextPowerOfTwo (v);
+	UInt32 prevPower = nextPower >> 1;
+	if (v - prevPower < nextPower - v)
+		return prevPower;
+	else
+		return nextPower;
+}
+
+inline UInt32 ToggleBit (UInt32 bitfield, int index)
+{
+	AssertIf (index < 0 || index >= 32);
+	return bitfield ^ (1 << index);
+}
+
+// Template argument must be a power of 2
+template<int n>
+struct StaticLog2
+{
+	static const int value = StaticLog2<n/2>::value + 1;
+};
+
+template<>
+struct StaticLog2<1>
+{
+	static const int value = 0;
+};
+
+#endif