110 lines
3.5 KiB
C
110 lines
3.5 KiB
C
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions
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// are met:
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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// * Neither the name of NVIDIA CORPORATION nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
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// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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// Copyright (c) 2008-2019 NVIDIA Corporation. All rights reserved.
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// Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
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// Copyright (c) 2001-2004 NovodeX AG. All rights reserved.
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#ifndef PSFOUNDATION_PSBITUTILS_H
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#define PSFOUNDATION_PSBITUTILS_H
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#include "foundation/PxIntrinsics.h"
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#include "foundation/PxAssert.h"
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#include "PsIntrinsics.h"
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#include "Ps.h"
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namespace physx
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{
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namespace shdfnd
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{
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PX_INLINE uint32_t bitCount(uint32_t v)
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{
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// from http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
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uint32_t const w = v - ((v >> 1) & 0x55555555);
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uint32_t const x = (w & 0x33333333) + ((w >> 2) & 0x33333333);
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return (((x + (x >> 4)) & 0xF0F0F0F) * 0x1010101) >> 24;
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}
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PX_INLINE bool isPowerOfTwo(uint32_t x)
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{
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return x != 0 && (x & (x - 1)) == 0;
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}
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// "Next Largest Power of 2
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// Given a binary integer value x, the next largest power of 2 can be computed by a SWAR algorithm
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// that recursively "folds" the upper bits into the lower bits. This process yields a bit vector with
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// the same most significant 1 as x, but all 1's below it. Adding 1 to that value yields the next
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// largest power of 2. For a 32-bit value:"
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PX_INLINE uint32_t nextPowerOfTwo(uint32_t x)
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{
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x |= (x >> 1);
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x |= (x >> 2);
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x |= (x >> 4);
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x |= (x >> 8);
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x |= (x >> 16);
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return x + 1;
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}
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/*!
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Return the index of the highest set bit. Not valid for zero arg.
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*/
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PX_INLINE uint32_t lowestSetBit(uint32_t x)
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{
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PX_ASSERT(x);
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return lowestSetBitUnsafe(x);
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}
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/*!
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Return the index of the highest set bit. Not valid for zero arg.
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*/
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PX_INLINE uint32_t highestSetBit(uint32_t x)
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{
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PX_ASSERT(x);
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return highestSetBitUnsafe(x);
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}
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// Helper function to approximate log2 of an integer value
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// assumes that the input is actually power of two.
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// todo: replace 2 usages with 'highestSetBit'
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PX_INLINE uint32_t ilog2(uint32_t num)
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{
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for(uint32_t i = 0; i < 32; i++)
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{
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num >>= 1;
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if(num == 0)
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return i;
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}
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PX_ASSERT(0);
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return uint32_t(-1);
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}
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} // namespace shdfnd
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} // namespace physx
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#endif // #ifndef PSFOUNDATION_PSBITUTILS_H
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