[U-Boot] [PATCH v8 1/4] include: Add log2 and fls64 header fi
Jagan Teki
jteki at openedev.com
Mon Oct 19 13:33:22 CEST 2015
On 17 October 2015 at 02:11, Fabio Estevam <festevam at gmail.com> wrote:
> From: Fabio Estevam <fabio.estevam at freescale.com>
>
> Use the log2 and fls64 header files directly from the kernel.
>
> Signed-off-by: Fabio Estevam <fabio.estevam at freescale.com>
> ---
> Changes since v7:
> - None
>
> include/asm-generic/bitops/fls64.h | 36 +++++++
> include/linux/bitops.h | 9 ++
> include/linux/log2.h | 208 +++++++++++++++++++++++++++++++++++++
> 3 files changed, 253 insertions(+)
> create mode 100644 include/asm-generic/bitops/fls64.h
> create mode 100644 include/linux/log2.h
>
> diff --git a/include/asm-generic/bitops/fls64.h b/include/asm-generic/bitops/fls64.h
> new file mode 100644
> index 0000000..86d403f
> --- /dev/null
> +++ b/include/asm-generic/bitops/fls64.h
> @@ -0,0 +1,36 @@
> +#ifndef _ASM_GENERIC_BITOPS_FLS64_H_
> +#define _ASM_GENERIC_BITOPS_FLS64_H_
> +
> +#include <asm/types.h>
> +
> +/**
> + * fls64 - find last set bit in a 64-bit word
> + * @x: the word to search
> + *
> + * This is defined in a similar way as the libc and compiler builtin
> + * ffsll, but returns the position of the most significant set bit.
> + *
> + * fls64(value) returns 0 if value is 0 or the position of the last
> + * set bit if value is nonzero. The last (most significant) bit is
> + * at position 64.
> + */
> +#if BITS_PER_LONG == 32
> +static inline int fls64(__u64 x)
> +{
> + __u32 h = x >> 32;
> + if (h)
> + return fls(h) + 32;
> + return fls(x);
> +}
> +#elif BITS_PER_LONG == 64
> +static inline int fls64(__u64 x)
> +{
> + if (x == 0)
> + return 0;
> + return __fls(x) + 1;
> +}
> +#else
> +#error BITS_PER_LONG not 32 or 64
> +#endif
> +
> +#endif /* _ASM_GENERIC_BITOPS_FLS64_H_ */
> diff --git a/include/linux/bitops.h b/include/linux/bitops.h
> index 7d30ace..647733f 100644
> --- a/include/linux/bitops.h
> +++ b/include/linux/bitops.h
> @@ -129,6 +129,15 @@ static inline unsigned int generic_hweight8(unsigned int w)
> # define fls generic_fls
> #endif
>
> +#include <asm-generic/bitops/fls64.h>
Please check this include, we can't assume to use generic one in
common header file there is one more fls64 from powerpc?
> +
> +static inline unsigned fls_long(unsigned long l)
> +{
> + if (sizeof(l) == 4)
> + return fls(l);
> + return fls64(l);
> +}
> +
> /**
> * __set_bit - Set a bit in memory
> * @nr: the bit to set
> diff --git a/include/linux/log2.h b/include/linux/log2.h
> new file mode 100644
> index 0000000..fd7ff3d
> --- /dev/null
> +++ b/include/linux/log2.h
> @@ -0,0 +1,208 @@
> +/* Integer base 2 logarithm calculation
> + *
> + * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
> + * Written by David Howells (dhowells at 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.
> + */
Wolfgang Denk/Tom,
This file is copied from Linux, will this license notes will also be
same or any changes?
> +
> +#ifndef _LINUX_LOG2_H
> +#define _LINUX_LOG2_H
> +
> +#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
> + * more efficiently than using fls() and fls64()
> + * - the arch is not required to handle n==0 if implementing the fallback
> + */
> +#ifndef CONFIG_ARCH_HAS_ILOG2_U32
> +static inline __attribute__((const))
> +int __ilog2_u32(u32 n)
> +{
> + return fls(n) - 1;
> +}
> +#endif
> +
> +#ifndef CONFIG_ARCH_HAS_ILOG2_U64
> +static inline __attribute__((const))
> +int __ilog2_u64(u64 n)
> +{
> + return fls64(n) - 1;
> +}
> +#endif
> +
> +/*
> + * Determine whether some value is a power of two, where zero is
> + * *not* considered a power of two.
> + */
> +
> +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
> + */
> +static inline __attribute__((const))
> +unsigned long __roundup_pow_of_two(unsigned long n)
> +{
> + return 1UL << fls_long(n - 1);
> +}
> +
> +/*
> + * round down to nearest power of two
> + */
> +static inline __attribute__((const))
> +unsigned long __rounddown_pow_of_two(unsigned long n)
> +{
> + return 1UL << (fls_long(n) - 1);
> +}
> +
> +/**
> + * ilog2 - log of 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
> + *
> + * selects the appropriately-sized optimised version depending on sizeof(n)
> + */
> +#define ilog2(n) \
> +( \
> + __builtin_constant_p(n) ? ( \
> + (n) < 1 ? ____ilog2_NaN() : \
> + (n) & (1ULL << 63) ? 63 : \
> + (n) & (1ULL << 62) ? 62 : \
> + (n) & (1ULL << 61) ? 61 : \
> + (n) & (1ULL << 60) ? 60 : \
> + (n) & (1ULL << 59) ? 59 : \
> + (n) & (1ULL << 58) ? 58 : \
> + (n) & (1ULL << 57) ? 57 : \
> + (n) & (1ULL << 56) ? 56 : \
> + (n) & (1ULL << 55) ? 55 : \
> + (n) & (1ULL << 54) ? 54 : \
> + (n) & (1ULL << 53) ? 53 : \
> + (n) & (1ULL << 52) ? 52 : \
> + (n) & (1ULL << 51) ? 51 : \
> + (n) & (1ULL << 50) ? 50 : \
> + (n) & (1ULL << 49) ? 49 : \
> + (n) & (1ULL << 48) ? 48 : \
> + (n) & (1ULL << 47) ? 47 : \
> + (n) & (1ULL << 46) ? 46 : \
> + (n) & (1ULL << 45) ? 45 : \
> + (n) & (1ULL << 44) ? 44 : \
> + (n) & (1ULL << 43) ? 43 : \
> + (n) & (1ULL << 42) ? 42 : \
> + (n) & (1ULL << 41) ? 41 : \
> + (n) & (1ULL << 40) ? 40 : \
> + (n) & (1ULL << 39) ? 39 : \
> + (n) & (1ULL << 38) ? 38 : \
> + (n) & (1ULL << 37) ? 37 : \
> + (n) & (1ULL << 36) ? 36 : \
> + (n) & (1ULL << 35) ? 35 : \
> + (n) & (1ULL << 34) ? 34 : \
> + (n) & (1ULL << 33) ? 33 : \
> + (n) & (1ULL << 32) ? 32 : \
> + (n) & (1ULL << 31) ? 31 : \
> + (n) & (1ULL << 30) ? 30 : \
> + (n) & (1ULL << 29) ? 29 : \
> + (n) & (1ULL << 28) ? 28 : \
> + (n) & (1ULL << 27) ? 27 : \
> + (n) & (1ULL << 26) ? 26 : \
> + (n) & (1ULL << 25) ? 25 : \
> + (n) & (1ULL << 24) ? 24 : \
> + (n) & (1ULL << 23) ? 23 : \
> + (n) & (1ULL << 22) ? 22 : \
> + (n) & (1ULL << 21) ? 21 : \
> + (n) & (1ULL << 20) ? 20 : \
> + (n) & (1ULL << 19) ? 19 : \
> + (n) & (1ULL << 18) ? 18 : \
> + (n) & (1ULL << 17) ? 17 : \
> + (n) & (1ULL << 16) ? 16 : \
> + (n) & (1ULL << 15) ? 15 : \
> + (n) & (1ULL << 14) ? 14 : \
> + (n) & (1ULL << 13) ? 13 : \
> + (n) & (1ULL << 12) ? 12 : \
> + (n) & (1ULL << 11) ? 11 : \
> + (n) & (1ULL << 10) ? 10 : \
> + (n) & (1ULL << 9) ? 9 : \
> + (n) & (1ULL << 8) ? 8 : \
> + (n) & (1ULL << 7) ? 7 : \
> + (n) & (1ULL << 6) ? 6 : \
> + (n) & (1ULL << 5) ? 5 : \
> + (n) & (1ULL << 4) ? 4 : \
> + (n) & (1ULL << 3) ? 3 : \
> + (n) & (1ULL << 2) ? 2 : \
> + (n) & (1ULL << 1) ? 1 : \
> + (n) & (1ULL << 0) ? 0 : \
> + ____ilog2_NaN() \
> + ) : \
> + (sizeof(n) <= 4) ? \
> + __ilog2_u32(n) : \
> + __ilog2_u64(n) \
> + )
> +
> +/**
> + * roundup_pow_of_two - round the given value up to nearest power of two
> + * @n - parameter
> + *
> + * round the given value up to the nearest power of two
> + * - the result is undefined when n == 0
> + * - this can be used to initialise global variables from constant data
> + */
> +#define roundup_pow_of_two(n) \
> +( \
> + __builtin_constant_p(n) ? ( \
> + (n == 1) ? 1 : \
> + (1UL << (ilog2((n) - 1) + 1)) \
> + ) : \
> + __roundup_pow_of_two(n) \
> + )
> +
> +/**
> + * rounddown_pow_of_two - round the given value down to nearest power of two
> + * @n - parameter
> + *
> + * round the given value down to the nearest power of two
> + * - the result is undefined when n == 0
> + * - this can be used to initialise global variables from constant data
> + */
> +#define rounddown_pow_of_two(n) \
> +( \
> + __builtin_constant_p(n) ? ( \
> + (1UL << ilog2(n))) : \
> + __rounddown_pow_of_two(n) \
> + )
> +
> +/**
> + * order_base_2 - calculate the (rounded up) base 2 order of the argument
> + * @n: parameter
> + *
> + * The first few values calculated by this routine:
> + * ob2(0) = 0
> + * ob2(1) = 0
> + * ob2(2) = 1
> + * ob2(3) = 2
> + * ob2(4) = 2
> + * ob2(5) = 3
> + * ... and so on.
> + */
> +
> +#define order_base_2(n) ilog2(roundup_pow_of_two(n))
> +
> +#endif /* _LINUX_LOG2_H */
> --
> 1.9.1
-- Jagan.
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