410 lines
14 KiB
C
410 lines
14 KiB
C
/*************************************************************************/ /*!
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@Title Integer log2 and related functions
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@Copyright Copyright (c) Imagination Technologies Ltd. All Rights Reserved
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@License Dual MIT/GPLv2
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The contents of this file are subject to the MIT license as set out below.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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Alternatively, the contents of this file may be used under the terms of
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the GNU General Public License Version 2 ("GPL") in which case the provisions
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of GPL are applicable instead of those above.
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If you wish to allow use of your version of this file only under the terms of
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GPL, and not to allow others to use your version of this file under the terms
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of the MIT license, indicate your decision by deleting the provisions above
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and replace them with the notice and other provisions required by GPL as set
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out in the file called "GPL-COPYING" included in this distribution. If you do
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not delete the provisions above, a recipient may use your version of this file
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under the terms of either the MIT license or GPL.
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This License is also included in this distribution in the file called
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"MIT-COPYING".
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EXCEPT AS OTHERWISE STATED IN A NEGOTIATED AGREEMENT: (A) THE SOFTWARE IS
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PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
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BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
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PURPOSE AND NONINFRINGEMENT; AND (B) IN NO EVENT SHALL THE AUTHORS OR
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COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/ /**************************************************************************/
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#ifndef LOG2_H
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#define LOG2_H
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#include "img_defs.h"
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/*************************************************************************/ /*!
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@Description Determine if a number is a power of two.
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@Input n
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@Return True if n is a power of 2, false otherwise. True if n == 0.
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*/ /**************************************************************************/
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static INLINE IMG_BOOL __const_function IsPower2(uint32_t n)
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{
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/* C++ needs this cast. */
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return (IMG_BOOL)((n & (n - 1U)) == 0U);
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}
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/*************************************************************************/ /*!
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@Description Determine if a number is a power of two.
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@Input n
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@Return True if n is a power of 2, false otherwise. True if n == 0.
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*/ /**************************************************************************/
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static INLINE IMG_BOOL __const_function IsPower2_64(uint64_t n)
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{
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/* C++ needs this cast. */
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return (IMG_BOOL)((n & (n - 1U)) == 0U);
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}
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/* Code using GNU GCC intrinsics */
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#if (defined(__GNUC__) || defined(__GNUG__)) && !(defined(__clang__) || defined(__INTEL_COMPILER))
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/* CHAR_BIT is typically found in <limits.h>. For all the platforms where
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* CHAR_BIT is not available, defined it here with the assumption that there
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* are 8 bits in a byte */
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#ifndef CHAR_BIT
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#define CHAR_BIT 8U
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#endif
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/*************************************************************************/ /*!
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@Description Compute floor(log2(n))
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@Input n
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@Return log2(n) rounded down to the nearest integer. Returns 0 if n == 0
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function FloorLog2(uint32_t n)
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{
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if (unlikely(n == 0U))
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{
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return 0;
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}
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else
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{
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uint32_t uNumBits = (uint32_t)CHAR_BIT * (uint32_t)sizeof(n);
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return uNumBits - (uint32_t)__builtin_clz(n) - 1U;
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}
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}
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/*************************************************************************/ /*!
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@Description Compute floor(log2(n))
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@Input n
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@Return log2(n) rounded down to the nearest integer. Returns 0 if n == 0
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function FloorLog2_64(uint64_t n)
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{
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if (unlikely(n == 0U))
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{
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return 0;
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}
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else
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{
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uint32_t uNumBits = (uint32_t)CHAR_BIT * (uint32_t)sizeof(n);
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return uNumBits - (uint32_t)__builtin_clzll(n) - 1U;
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}
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}
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/*************************************************************************/ /*!
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@Description Compute ceil(log2(n))
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@Input n
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@Return log2(n) rounded up to the nearest integer. Returns 0 if n == 0
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function CeilLog2(uint32_t n)
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{
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if (unlikely(n == 0U || n == 1U))
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{
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return 0;
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}
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else
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{
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uint32_t uNumBits = (uint32_t)CHAR_BIT * (uint32_t)sizeof(n);
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n--; /* Handle powers of 2 */
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return uNumBits - (uint32_t)__builtin_clz(n);
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}
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}
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/*************************************************************************/ /*!
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@Description Compute ceil(log2(n))
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@Input n
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@Return log2(n) rounded up to the nearest integer. Returns 0 if n == 0
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function CeilLog2_64(uint64_t n)
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{
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if (unlikely(n == 0U || n == 1U))
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{
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return 0;
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}
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else
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{
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uint32_t uNumBits = (uint32_t)CHAR_BIT * (uint32_t)sizeof(n);
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n--; /* Handle powers of 2 */
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return uNumBits - (uint32_t)__builtin_clzll(n);
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}
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}
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/*************************************************************************/ /*!
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@Description Compute log2(n) for exact powers of two only
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@Input n Must be a power of two
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@Return log2(n)
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function ExactLog2(uint32_t n)
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{
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return (uint32_t)CHAR_BIT * (uint32_t)sizeof(n) - (uint32_t)__builtin_clz(n) - 1U;
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}
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/*************************************************************************/ /*!
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@Description Compute log2(n) for exact powers of two only
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@Input n Must be a power of two
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@Return log2(n)
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function ExactLog2_64(uint64_t n)
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{
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return (uint32_t)CHAR_BIT * (uint32_t)sizeof(n) - (uint32_t)__builtin_clzll(n) - 1U;
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}
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/*************************************************************************/ /*!
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@Description Round a non-power-of-two number up to the next power of two.
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@Input n
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@Return n rounded up to the next power of two. If n is zero or
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already a power of two, return n unmodified.
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function RoundUpToNextPowerOfTwo(uint32_t n)
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{
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/* Cases with n greater than 2^31 needs separate handling
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* as result of (1<<32) is undefined. */
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if (unlikely( n == 0U || n > (uint32_t)1 << ((uint32_t)CHAR_BIT * sizeof(n) - 1U)))
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{
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return 0;
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}
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/* Return n if it is already a power of 2 */
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if ((IMG_BOOL)((n & (n - 1U)) == 0U))
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{
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return n;
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}
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return (uint32_t)1 << ((uint32_t)CHAR_BIT * sizeof(n) - (uint32_t)__builtin_clz(n));
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}
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/*************************************************************************/ /*!
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@Description Round a non-power-of-two number up to the next power of two.
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@Input n
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@Return n rounded up to the next power of two. If n is zero or
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already a power of two, return n unmodified.
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*/ /**************************************************************************/
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static INLINE uint64_t __const_function RoundUpToNextPowerOfTwo_64(uint64_t n)
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{
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/* Cases with n greater than 2^63 needs separate handling
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* as result of (1<<64) is undefined. */
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if (unlikely( n == 0U || n > (uint64_t)1 << ((uint32_t)CHAR_BIT * sizeof(n) - 1U)))
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{
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return 0;
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}
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/* Return n if it is already a power of 2 */
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if ((IMG_BOOL)((n & (n - 1U)) == 0U))
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{
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return n;
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}
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return (uint64_t)1 << ((uint64_t)CHAR_BIT * sizeof(n) - (uint64_t)__builtin_clzll(n));
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}
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#else /* #if (defined(__GNUC__) || defined(__GNUG__)) && !(defined(__clang__) || defined(__INTEL_COMPILER)) */
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/*************************************************************************/ /*!
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@Description Round a non-power-of-two number up to the next power of two.
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@Input n
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@Return n rounded up to the next power of two. If n is zero or
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already a power of two, return n unmodified.
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function RoundUpToNextPowerOfTwo(uint32_t n)
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{
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n--;
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n |= n >> 1; /* handle 2 bit numbers */
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n |= n >> 2; /* handle 4 bit numbers */
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n |= n >> 4; /* handle 8 bit numbers */
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n |= n >> 8; /* handle 16 bit numbers */
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n |= n >> 16; /* handle 32 bit numbers */
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n++;
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return n;
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}
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/*************************************************************************/ /*!
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@Description Round a non-power-of-two number up to the next power of two.
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@Input n
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@Return n rounded up to the next power of two. If n is zero or
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already a power of two, return n unmodified.
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*/ /**************************************************************************/
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static INLINE uint64_t __const_function RoundUpToNextPowerOfTwo_64(uint64_t n)
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{
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n--;
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n |= n >> 1; /* handle 2 bit numbers */
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n |= n >> 2; /* handle 4 bit numbers */
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n |= n >> 4; /* handle 8 bit numbers */
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n |= n >> 8; /* handle 16 bit numbers */
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n |= n >> 16; /* handle 32 bit numbers */
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n |= n >> 32; /* handle 64 bit numbers */
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n++;
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return n;
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}
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/*************************************************************************/ /*!
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@Description Compute floor(log2(n))
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@Input n
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@Return log2(n) rounded down to the nearest integer. Returns 0 if n == 0
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function FloorLog2(uint32_t n)
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{
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uint32_t log2 = 0;
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while (n >>= 1)
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log2++;
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return log2;
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}
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/*************************************************************************/ /*!
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@Description Compute floor(log2(n))
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@Input n
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@Return log2(n) rounded down to the nearest integer. Returns 0 if n == 0
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function FloorLog2_64(uint64_t n)
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{
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uint32_t log2 = 0;
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while (n >>= 1)
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log2++;
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return log2;
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}
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/*************************************************************************/ /*!
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@Description Compute ceil(log2(n))
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@Input n
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@Return log2(n) rounded up to the nearest integer. Returns 0 if n == 0
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function CeilLog2(uint32_t n)
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{
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uint32_t log2 = 0;
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if (n == 0)
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return 0;
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n--; /* Handle powers of 2 */
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while (n)
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{
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log2++;
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n >>= 1;
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}
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return log2;
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}
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/*************************************************************************/ /*!
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@Description Compute ceil(log2(n))
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@Input n
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@Return log2(n) rounded up to the nearest integer. Returns 0 if n == 0
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function CeilLog2_64(uint64_t n)
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{
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uint32_t log2 = 0;
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if (n == 0)
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return 0;
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n--; /* Handle powers of 2 */
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while (n)
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{
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log2++;
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n >>= 1;
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}
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return log2;
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}
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/*************************************************************************/ /*!
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@Description Compute log2(n) for exact powers of two only
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@Input n Must be a power of two
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@Return log2(n)
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function ExactLog2(uint32_t n)
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{
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static const uint32_t b[] =
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{0xAAAAAAAA, 0xCCCCCCCC, 0xF0F0F0F0, 0xFF00FF00, 0xFFFF0000};
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uint32_t r = (n & b[0]) != 0;
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r |= (uint32_t) ((n & b[4]) != 0) << 4;
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r |= (uint32_t) ((n & b[3]) != 0) << 3;
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r |= (uint32_t) ((n & b[2]) != 0) << 2;
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r |= (uint32_t) ((n & b[1]) != 0) << 1;
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return r;
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}
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/*************************************************************************/ /*!
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@Description Compute log2(n) for exact powers of two only
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@Input n Must be a power of two
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@Return log2(n)
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function ExactLog2_64(uint64_t n)
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{
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static const uint64_t b[] =
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{0xAAAAAAAAAAAAAAAAULL, 0xCCCCCCCCCCCCCCCCULL,
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0xF0F0F0F0F0F0F0F0ULL, 0xFF00FF00FF00FF00ULL,
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0xFFFF0000FFFF0000ULL, 0xFFFFFFFF00000000ULL};
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uint32_t r = (n & b[0]) != 0;
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r |= (uint32_t) ((n & b[5]) != 0) << 5;
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r |= (uint32_t) ((n & b[4]) != 0) << 4;
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r |= (uint32_t) ((n & b[3]) != 0) << 3;
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r |= (uint32_t) ((n & b[2]) != 0) << 2;
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r |= (uint32_t) ((n & b[1]) != 0) << 1;
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return r;
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}
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#endif /* #if (defined(__GNUC__) || defined(__GNUG__)) && !(defined(__clang__) || defined(__INTEL_COMPILER)) */
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/*************************************************************************/ /*!
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@Description Compute floor(log2(size)) , where size is the max of 3 sizes
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This is almost always the ONLY EVER valid use of FloorLog2.
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Usually CeilLog2() should be used instead.
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For a 5x5x1 texture, the 3 miplevels are:
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0: 5x5x1
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1: 2x2x1
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2: 1x1x1
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For an 8x8x1 texture, the 4 miplevels are:
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0: 8x8x1
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1: 4x4x1
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2: 2x2x1
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3: 1x1x1
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@Input sizeX, sizeY, sizeZ
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@Return Count of mipmap levels for given dimensions
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*/ /**************************************************************************/
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static INLINE uint32_t __const_function NumMipLevels(uint32_t sizeX, uint32_t sizeY, uint32_t sizeZ)
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{
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uint32_t maxSize = MAX(MAX(sizeX, sizeY), sizeZ);
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return FloorLog2(maxSize) + 1U;
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}
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#endif /* LOG2_H */
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