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	include: update log2 header from the Linux kernel
Without the patch gcc 8 produces: warning: ignoring attribute ‘noreturn’ because it conflicts with attribute ‘const’ [-Wattributes] int ____ilog2_NaN(void); So let's update the include from Linux kernel v4.16. This removes static checks of ilog2() arguments. Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
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						 Tom Rini
						Tom Rini
					
				
			
			
				
	
			
			
			
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			| @@ -3,6 +3,11 @@ | ||||
|  * | ||||
|  * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. | ||||
|  * Written by David Howells (dhowells@redhat.com) | ||||
|  * | ||||
|  * This program is free software; you can redistribute it and/or | ||||
|  * modify it under the terms of the GNU General Public License | ||||
|  * as published by the Free Software Foundation; either version | ||||
|  * 2 of the License, or (at your option) any later version. | ||||
|  */ | ||||
|  | ||||
| #ifndef _LINUX_LOG2_H | ||||
| @@ -11,12 +16,6 @@ | ||||
| #include <linux/types.h> | ||||
| #include <linux/bitops.h> | ||||
|  | ||||
| /* | ||||
|  * deal with unrepresentable constant logarithms | ||||
|  */ | ||||
| extern __attribute__((const, noreturn)) | ||||
| int ____ilog2_NaN(void); | ||||
|  | ||||
| /* | ||||
|  * non-constant log of base 2 calculators | ||||
|  * - the arch may override these in asm/bitops.h if they can be implemented | ||||
| @@ -39,19 +38,23 @@ int __ilog2_u64(u64 n) | ||||
| } | ||||
| #endif | ||||
|  | ||||
| /* | ||||
|  *  Determine whether some value is a power of two, where zero is | ||||
| /** | ||||
|  * is_power_of_2() - check if a value is a power of two | ||||
|  * @n: the value to check | ||||
|  * | ||||
|  * Determine whether some value is a power of two, where zero is | ||||
|  * *not* considered a power of two. | ||||
|  * Return: true if @n is a power of 2, otherwise false. | ||||
|  */ | ||||
|  | ||||
| static inline __attribute__((const)) | ||||
| bool is_power_of_2(unsigned long n) | ||||
| { | ||||
| 	return (n != 0 && ((n & (n - 1)) == 0)); | ||||
| } | ||||
|  | ||||
| /* | ||||
|  * round up to nearest power of two | ||||
| /** | ||||
|  * __roundup_pow_of_two() - round up to nearest power of two | ||||
|  * @n: value to round up | ||||
|  */ | ||||
| static inline __attribute__((const)) | ||||
| unsigned long __roundup_pow_of_two(unsigned long n) | ||||
| @@ -59,8 +62,9 @@ unsigned long __roundup_pow_of_two(unsigned long n) | ||||
| 	return 1UL << fls_long(n - 1); | ||||
| } | ||||
|  | ||||
| /* | ||||
|  * round down to nearest power of two | ||||
| /** | ||||
|  * __rounddown_pow_of_two() - round down to nearest power of two | ||||
|  * @n: value to round down | ||||
|  */ | ||||
| static inline __attribute__((const)) | ||||
| unsigned long __rounddown_pow_of_two(unsigned long n) | ||||
| @@ -69,19 +73,19 @@ unsigned long __rounddown_pow_of_two(unsigned long n) | ||||
| } | ||||
|  | ||||
| /** | ||||
|  * ilog2 - log of base 2 of 32-bit or a 64-bit unsigned value | ||||
|  * @n - parameter | ||||
|  * ilog2 - log base 2 of 32-bit or a 64-bit unsigned value | ||||
|  * @n: parameter | ||||
|  * | ||||
|  * constant-capable log of base 2 calculation | ||||
|  * - this can be used to initialise global variables from constant data, hence | ||||
|  *   the massive ternary operator construction | ||||
|  * the massive ternary operator construction | ||||
|  * | ||||
|  * selects the appropriately-sized optimised version depending on sizeof(n) | ||||
|  */ | ||||
| #define ilog2(n)				\ | ||||
| (						\ | ||||
| 	__builtin_constant_p(n) ? (		\ | ||||
| 		(n) < 1 ? ____ilog2_NaN() :	\ | ||||
| 		(n) < 2 ? 0 :			\ | ||||
| 		(n) & (1ULL << 63) ? 63 :	\ | ||||
| 		(n) & (1ULL << 62) ? 62 :	\ | ||||
| 		(n) & (1ULL << 61) ? 61 :	\ | ||||
| @@ -144,10 +148,7 @@ unsigned long __rounddown_pow_of_two(unsigned long n) | ||||
| 		(n) & (1ULL <<  4) ?  4 :	\ | ||||
| 		(n) & (1ULL <<  3) ?  3 :	\ | ||||
| 		(n) & (1ULL <<  2) ?  2 :	\ | ||||
| 		(n) & (1ULL <<  1) ?  1 :	\ | ||||
| 		(n) & (1ULL <<  0) ?  0 :	\ | ||||
| 		____ilog2_NaN()			\ | ||||
| 				   ) :		\ | ||||
| 		1) :				\ | ||||
| 	(sizeof(n) <= 4) ?			\ | ||||
| 	__ilog2_u32(n) :			\ | ||||
| 	__ilog2_u64(n)				\ | ||||
| @@ -155,7 +156,7 @@ unsigned long __rounddown_pow_of_two(unsigned long n) | ||||
|  | ||||
| /** | ||||
|  * roundup_pow_of_two - round the given value up to nearest power of two | ||||
|  * @n - parameter | ||||
|  * @n: parameter | ||||
|  * | ||||
|  * round the given value up to the nearest power of two | ||||
|  * - the result is undefined when n == 0 | ||||
| @@ -172,7 +173,7 @@ unsigned long __rounddown_pow_of_two(unsigned long n) | ||||
|  | ||||
| /** | ||||
|  * rounddown_pow_of_two - round the given value down to nearest power of two | ||||
|  * @n - parameter | ||||
|  * @n: parameter | ||||
|  * | ||||
|  * round the given value down to the nearest power of two | ||||
|  * - the result is undefined when n == 0 | ||||
| @@ -185,6 +186,12 @@ unsigned long __rounddown_pow_of_two(unsigned long n) | ||||
| 	__rounddown_pow_of_two(n)		\ | ||||
|  ) | ||||
|  | ||||
| static inline __attribute_const__ | ||||
| int __order_base_2(unsigned long n) | ||||
| { | ||||
| 	return n > 1 ? ilog2(n - 1) + 1 : 0; | ||||
| } | ||||
|  | ||||
| /** | ||||
|  * order_base_2 - calculate the (rounded up) base 2 order of the argument | ||||
|  * @n: parameter | ||||
| @@ -198,7 +205,11 @@ unsigned long __rounddown_pow_of_two(unsigned long n) | ||||
|  *  ob2(5) = 3 | ||||
|  *  ... and so on. | ||||
|  */ | ||||
|  | ||||
| #define order_base_2(n) ilog2(roundup_pow_of_two(n)) | ||||
|  | ||||
| #define order_base_2(n)				\ | ||||
| (						\ | ||||
| 	__builtin_constant_p(n) ? (		\ | ||||
| 		((n) == 0 || (n) == 1) ? 0 :	\ | ||||
| 		ilog2((n) - 1) + 1) :		\ | ||||
| 	__order_base_2(n)			\ | ||||
| ) | ||||
| #endif /* _LINUX_LOG2_H */ | ||||
|   | ||||
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