Revision control
- //
- // Redistribution and use in source and binary forms, with or without
- // modification, are permitted provided that the following conditions
- // are met:
- // * Redistributions of source code must retain the above copyright
- // notice, this list of conditions and the following disclaimer.
- // * Redistributions in binary form must reproduce the above copyright
- // notice, this list of conditions and the following disclaimer in the
- // documentation and/or other materials provided with the distribution.
- // * Neither the name of NVIDIA CORPORATION nor the names of its
- // contributors may be used to endorse or promote products derived
- // from this software without specific prior written permission.
- //
- // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
- // EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- // PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
- // CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- // EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
- // OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- //
- // Copyright (c) 2008-2021 NVIDIA Corporation. All rights reserved.
- // Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
- // Copyright (c) 2001-2004 NovodeX AG. All rights reserved.
-
- #ifndef PSFOUNDATION_PSBITUTILS_H
- #define PSFOUNDATION_PSBITUTILS_H
-
- #include "foundation/PxIntrinsics.h"
- #include "foundation/PxAssert.h"
- #include "PsIntrinsics.h"
- #include "Ps.h"
-
- namespace physx
- {
- namespace shdfnd
- {
- PX_INLINE uint32_t bitCount(uint32_t v)
- {
- // from http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
- uint32_t const w = v - ((v >> 1) & 0x55555555);
- uint32_t const x = (w & 0x33333333) + ((w >> 2) & 0x33333333);
- return (((x + (x >> 4)) & 0xF0F0F0F) * 0x1010101) >> 24;
- }
-
- PX_INLINE bool isPowerOfTwo(uint32_t x)
- {
- return x != 0 && (x & (x - 1)) == 0;
- }
-
- // "Next Largest Power of 2
- // Given a binary integer value x, the next largest power of 2 can be computed by a SWAR algorithm
- // that recursively "folds" the upper bits into the lower bits. This process yields a bit vector with
- // the same most significant 1 as x, but all 1's below it. Adding 1 to that value yields the next
- // largest power of 2. For a 32-bit value:"
- PX_INLINE uint32_t nextPowerOfTwo(uint32_t x)
- {
- x |= (x >> 1);
- x |= (x >> 2);
- x |= (x >> 4);
- x |= (x >> 8);
- x |= (x >> 16);
- return x + 1;
- }
-
- /*!
- Return the index of the highest set bit. Not valid for zero arg.
- */
-
- PX_INLINE uint32_t lowestSetBit(uint32_t x)
- {
- PX_ASSERT(x);
- return lowestSetBitUnsafe(x);
- }
-
- /*!
- Return the index of the highest set bit. Not valid for zero arg.
- */
-
- PX_INLINE uint32_t highestSetBit(uint32_t x)
- {
- PX_ASSERT(x);
- return highestSetBitUnsafe(x);
- }
-
- // Helper function to approximate log2 of an integer value
- // assumes that the input is actually power of two.
- // todo: replace 2 usages with 'highestSetBit'
- PX_INLINE uint32_t ilog2(uint32_t num)
- {
- for(uint32_t i = 0; i < 32; i++)
- {
- num >>= 1;
- if(num == 0)
- return i;
- }
-
- PX_ASSERT(0);
- return uint32_t(-1);
- }
-
- } // namespace shdfnd
- } // namespace physx
-
- #endif // #ifndef PSFOUNDATION_PSBITUTILS_H