Use the log2 and generic bitops header files directly from the kernel.
Based on the headers froom kernel 4.2.3.
Signed-off-by: Fabio Estevam fabio.estevam@freescale.com --- Changes since v8: - Do not mix generic versus arch specific header (Jagan) - Build tested on ARM, m68k, powerpc, bfin, microblaze, sh and x86
arch/arm/include/asm/bitops.h | 98 +++++++++++++++++ arch/blackfin/include/asm/bitops.h | 4 + arch/m68k/include/asm/bitops.h | 4 + arch/microblaze/include/asm/bitops.h | 4 + arch/powerpc/cpu/mpc83xx/law.c | 4 +- arch/powerpc/cpu/mpc85xx/tlb.c | 2 + arch/powerpc/cpu/mpc8xxx/law.c | 5 +- arch/powerpc/include/asm/bitops.h | 43 +------- arch/sh/include/asm/bitops.h | 5 + arch/x86/include/asm/bitops.h | 6 +- drivers/pci/fsl_pci_init.c | 1 + include/asm-generic/bitops/__ffs.h | 43 ++++++++ include/asm-generic/bitops/__fls.h | 43 ++++++++ include/asm-generic/bitops/ffs.h | 41 +++++++ include/asm-generic/bitops/fls.h | 41 +++++++ include/asm-generic/bitops/fls64.h | 36 ++++++ include/linux/bitops.h | 26 +++++ include/linux/log2.h | 205 +++++++++++++++++++++++++++++++++++ 18 files changed, 566 insertions(+), 45 deletions(-) create mode 100644 include/asm-generic/bitops/__ffs.h create mode 100644 include/asm-generic/bitops/__fls.h create mode 100644 include/asm-generic/bitops/ffs.h create mode 100644 include/asm-generic/bitops/fls.h create mode 100644 include/asm-generic/bitops/fls64.h create mode 100644 include/linux/log2.h
diff --git a/arch/arm/include/asm/bitops.h b/arch/arm/include/asm/bitops.h index 9b78043..cbc07ae 100644 --- a/arch/arm/include/asm/bitops.h +++ b/arch/arm/include/asm/bitops.h @@ -190,4 +190,102 @@ found_middle:
#endif /* __KERNEL__ */
+#if __LINUX_ARM_ARCH__ < 5 + +#include <asm-generic/bitops/__fls.h> +#include <asm-generic/bitops/__ffs.h> +#include <asm-generic/bitops/fls.h> +#include <asm-generic/bitops/ffs.h> + +#else + +static inline int constant_fls(int x) +{ + int r = 32; + + if (!x) + return 0; + if (!(x & 0xffff0000u)) { + x <<= 16; + r -= 16; + } + if (!(x & 0xff000000u)) { + x <<= 8; + r -= 8; + } + if (!(x & 0xf0000000u)) { + x <<= 4; + r -= 4; + } + if (!(x & 0xc0000000u)) { + x <<= 2; + r -= 2; + } + if (!(x & 0x80000000u)) { + x <<= 1; + r -= 1; + } + return r; +} + +/* + * On ARMv5 and above those functions can be implemented around the + * clz instruction for much better code efficiency. __clz returns + * the number of leading zeros, zero input will return 32, and + * 0x80000000 will return 0. + */ +static inline unsigned int __clz(unsigned int x) +{ + unsigned int ret; + + asm("clz\t%0, %1" : "=r" (ret) : "r" (x)); + + return ret; +} + +/* + * fls() returns zero if the input is zero, otherwise returns the bit + * position of the last set bit, where the LSB is 1 and MSB is 32. + */ +static inline int fls(int x) +{ + if (__builtin_constant_p(x)) + return constant_fls(x); + + return 32 - __clz(x); +} + +/* + * __fls() returns the bit position of the last bit set, where the + * LSB is 0 and MSB is 31. Zero input is undefined. + */ +static inline unsigned long __fls(unsigned long x) +{ + return fls(x) - 1; +} + +/* + * ffs() returns zero if the input was zero, otherwise returns the bit + * position of the first set bit, where the LSB is 1 and MSB is 32. + */ +static inline int ffs(int x) +{ + return fls(x & -x); +} + +/* + * __ffs() returns the bit position of the first bit set, where the + * LSB is 0 and MSB is 31. Zero input is undefined. + */ +static inline unsigned long __ffs(unsigned long x) +{ + return ffs(x) - 1; +} + +#define ffz(x) __ffs( ~(x) ) + +#endif + +#include <asm-generic/bitops/fls64.h> + #endif /* _ARM_BITOPS_H */ diff --git a/arch/blackfin/include/asm/bitops.h b/arch/blackfin/include/asm/bitops.h index cd7e356..6cde6db 100644 --- a/arch/blackfin/include/asm/bitops.h +++ b/arch/blackfin/include/asm/bitops.h @@ -15,6 +15,10 @@
#include <asm/byteorder.h> #include <asm/system.h> +#include <asm-generic/bitops/fls.h> +#include <asm-generic/bitops/__fls.h> +#include <asm-generic/bitops/fls64.h> +#include <asm-generic/bitops/__ffs.h>
#ifdef __KERNEL__ /* diff --git a/arch/m68k/include/asm/bitops.h b/arch/m68k/include/asm/bitops.h index f9c434b..69ea26a 100644 --- a/arch/m68k/include/asm/bitops.h +++ b/arch/m68k/include/asm/bitops.h @@ -6,6 +6,10 @@ #define _M68K_BITOPS_H
#include <asm/byteorder.h> +#include <asm-generic/bitops/fls.h> +#include <asm-generic/bitops/__fls.h> +#include <asm-generic/bitops/fls64.h> +#include <asm-generic/bitops/__ffs.h>
extern void set_bit(int nr, volatile void *addr); extern void clear_bit(int nr, volatile void *addr); diff --git a/arch/microblaze/include/asm/bitops.h b/arch/microblaze/include/asm/bitops.h index 0ac78d7..d24f2cf 100644 --- a/arch/microblaze/include/asm/bitops.h +++ b/arch/microblaze/include/asm/bitops.h @@ -7,6 +7,10 @@
#include <asm/byteorder.h> /* swab32 */ #include <asm/system.h> /* save_flags */ +#include <asm-generic/bitops/fls.h> +#include <asm-generic/bitops/__fls.h> +#include <asm-generic/bitops/fls64.h> +#include <asm-generic/bitops/__ffs.h>
#ifdef __KERNEL__ /* diff --git a/arch/powerpc/cpu/mpc83xx/law.c b/arch/powerpc/cpu/mpc83xx/law.c index 66c88b6..d8173f4 100644 --- a/arch/powerpc/cpu/mpc83xx/law.c +++ b/arch/powerpc/cpu/mpc83xx/law.c @@ -20,7 +20,7 @@ int set_ddr_laws(u64 start, u64 sz, enum law_trgt_if id) if (start == 0) start_align = 1ull << (LAW_SIZE_2G + 1); else - start_align = 1ull << (ffs64(start) - 1); + start_align = 1ull << (__ffs64(start) - 1); law_sz = min(start_align, sz); law_sz_enc = __ilog2_u64(law_sz) - 1;
@@ -40,7 +40,7 @@ int set_ddr_laws(u64 start, u64 sz, enum law_trgt_if id) if (sz) { start += law_sz;
- start_align = 1ull << (ffs64(start) - 1); + start_align = 1ull << (__ffs64(start) - 1); law_sz = min(start_align, sz); law_sz_enc = __ilog2_u64(law_sz) - 1; ecm = &immap->sysconf.ddrlaw[1]; diff --git a/arch/powerpc/cpu/mpc85xx/tlb.c b/arch/powerpc/cpu/mpc85xx/tlb.c index 8e0508f..cf31eb2 100644 --- a/arch/powerpc/cpu/mpc85xx/tlb.c +++ b/arch/powerpc/cpu/mpc85xx/tlb.c @@ -14,6 +14,8 @@ #include <addr_map.h> #endif
+#include <linux/log2.h> + DECLARE_GLOBAL_DATA_PTR;
void invalidate_tlb(u8 tlb) diff --git a/arch/powerpc/cpu/mpc8xxx/law.c b/arch/powerpc/cpu/mpc8xxx/law.c index 33d53a8..24baad4 100644 --- a/arch/powerpc/cpu/mpc8xxx/law.c +++ b/arch/powerpc/cpu/mpc8xxx/law.c @@ -11,6 +11,7 @@ #include <linux/compiler.h> #include <asm/fsl_law.h> #include <asm/io.h> +#include <linux/log2.h>
DECLARE_GLOBAL_DATA_PTR;
@@ -187,7 +188,7 @@ int set_ddr_laws(u64 start, u64 sz, enum law_trgt_if id) if (start == 0) start_align = 1ull << (LAW_SIZE_32G + 1); else - start_align = 1ull << (ffs64(start) - 1); + start_align = 1ull << (__ffs64(start) - 1); law_sz = min(start_align, sz); law_sz_enc = __ilog2_u64(law_sz) - 1;
@@ -202,7 +203,7 @@ int set_ddr_laws(u64 start, u64 sz, enum law_trgt_if id) if (sz) { start += law_sz;
- start_align = 1ull << (ffs64(start) - 1); + start_align = 1ull << (__ffs64(start) - 1); law_sz = min(start_align, sz); law_sz_enc = __ilog2_u64(law_sz) - 1;
diff --git a/arch/powerpc/include/asm/bitops.h b/arch/powerpc/include/asm/bitops.h index a6bcf3c..a70bbba 100644 --- a/arch/powerpc/include/asm/bitops.h +++ b/arch/powerpc/include/asm/bitops.h @@ -6,6 +6,7 @@ #define _PPC_BITOPS_H
#include <asm/byteorder.h> +#include <asm-generic/bitops/__ffs.h>
extern void set_bit(int nr, volatile void *addr); extern void clear_bit(int nr, volatile void *addr); @@ -179,46 +180,6 @@ static __inline__ int fls(unsigned int x) } #define PLATFORM_FLS
-/** - * 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 __ilog2(x) + 1; -} -#else -#error BITS_PER_LONG not 32 or 64 -#endif - -static inline int __ilog2_u64(u64 n) -{ - return fls64(n) - 1; -} - -static inline int ffs64(u64 x) -{ - return __ilog2_u64(x & -x) + 1ull; -} - #ifdef __KERNEL__
/* @@ -232,6 +193,8 @@ extern __inline__ int ffs(int x) } #define PLATFORM_FFS
+#include <asm-generic/bitops/fls64.h> + /* * hweightN: returns the hamming weight (i.e. the number * of bits set) of a N-bit word diff --git a/arch/sh/include/asm/bitops.h b/arch/sh/include/asm/bitops.h index c57d628..8cb8385 100644 --- a/arch/sh/include/asm/bitops.h +++ b/arch/sh/include/asm/bitops.h @@ -1,6 +1,11 @@ #ifndef __ASM_SH_BITOPS_H #define __ASM_SH_BITOPS_H
+#include <asm-generic/bitops/fls.h> +#include <asm-generic/bitops/__fls.h> +#include <asm-generic/bitops/fls64.h> +#include <asm-generic/bitops/__ffs.h> + #ifdef __KERNEL__ #include <asm/irqflags.h> /* For __swab32 */ diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h index 5a7e4cb..a1622ae 100644 --- a/arch/x86/include/asm/bitops.h +++ b/arch/x86/include/asm/bitops.h @@ -22,6 +22,11 @@
#define ADDR (*(volatile long *) addr)
+#include <asm-generic/bitops/fls.h> +#include <asm-generic/bitops/__fls.h> +#include <asm-generic/bitops/fls64.h> +#include <asm-generic/bitops/__ffs.h> + /** * set_bit - Atomically set a bit in memory * @nr: the bit to set @@ -349,7 +354,6 @@ static __inline__ int ffs(int x) "1:" : "=r" (r) : "g" (x)); return r+1; } -#define PLATFORM_FFS
static inline int __ilog2(unsigned int x) { diff --git a/drivers/pci/fsl_pci_init.c b/drivers/pci/fsl_pci_init.c index 52792dc..27daf6d 100644 --- a/drivers/pci/fsl_pci_init.c +++ b/drivers/pci/fsl_pci_init.c @@ -7,6 +7,7 @@ #include <common.h> #include <malloc.h> #include <asm/fsl_serdes.h> +#include <linux/log2.h>
DECLARE_GLOBAL_DATA_PTR;
diff --git a/include/asm-generic/bitops/__ffs.h b/include/asm-generic/bitops/__ffs.h new file mode 100644 index 0000000..9a3274a --- /dev/null +++ b/include/asm-generic/bitops/__ffs.h @@ -0,0 +1,43 @@ +#ifndef _ASM_GENERIC_BITOPS___FFS_H_ +#define _ASM_GENERIC_BITOPS___FFS_H_ + +#include <asm/types.h> + +/** + * __ffs - find first bit in word. + * @word: The word to search + * + * Undefined if no bit exists, so code should check against 0 first. + */ +static inline unsigned long __ffs(unsigned long word) +{ + int num = 0; + +#if BITS_PER_LONG == 64 + if ((word & 0xffffffff) == 0) { + num += 32; + word >>= 32; + } +#endif + if ((word & 0xffff) == 0) { + num += 16; + word >>= 16; + } + if ((word & 0xff) == 0) { + num += 8; + word >>= 8; + } + if ((word & 0xf) == 0) { + num += 4; + word >>= 4; + } + if ((word & 0x3) == 0) { + num += 2; + word >>= 2; + } + if ((word & 0x1) == 0) + num += 1; + return num; +} + +#endif /* _ASM_GENERIC_BITOPS___FFS_H_ */ diff --git a/include/asm-generic/bitops/__fls.h b/include/asm-generic/bitops/__fls.h new file mode 100644 index 0000000..be24465 --- /dev/null +++ b/include/asm-generic/bitops/__fls.h @@ -0,0 +1,43 @@ +#ifndef _ASM_GENERIC_BITOPS___FLS_H_ +#define _ASM_GENERIC_BITOPS___FLS_H_ + +#include <asm/types.h> + +/** + * __fls - find last (most-significant) set bit in a long word + * @word: the word to search + * + * Undefined if no set bit exists, so code should check against 0 first. + */ +static inline unsigned long __fls(unsigned long word) +{ + int num = BITS_PER_LONG - 1; + +#if BITS_PER_LONG == 64 + if (!(word & (~0ul << 32))) { + num -= 32; + word <<= 32; + } +#endif + if (!(word & (~0ul << (BITS_PER_LONG-16)))) { + num -= 16; + word <<= 16; + } + if (!(word & (~0ul << (BITS_PER_LONG-8)))) { + num -= 8; + word <<= 8; + } + if (!(word & (~0ul << (BITS_PER_LONG-4)))) { + num -= 4; + word <<= 4; + } + if (!(word & (~0ul << (BITS_PER_LONG-2)))) { + num -= 2; + word <<= 2; + } + if (!(word & (~0ul << (BITS_PER_LONG-1)))) + num -= 1; + return num; +} + +#endif /* _ASM_GENERIC_BITOPS___FLS_H_ */ diff --git a/include/asm-generic/bitops/ffs.h b/include/asm-generic/bitops/ffs.h new file mode 100644 index 0000000..fbbb43a --- /dev/null +++ b/include/asm-generic/bitops/ffs.h @@ -0,0 +1,41 @@ +#ifndef _ASM_GENERIC_BITOPS_FFS_H_ +#define _ASM_GENERIC_BITOPS_FFS_H_ + +/** + * ffs - find first bit set + * @x: the word to search + * + * This is defined the same way as + * the libc and compiler builtin ffs routines, therefore + * differs in spirit from the above ffz (man ffs). + */ +static inline int ffs(int x) +{ + int r = 1; + + if (!x) + return 0; + if (!(x & 0xffff)) { + x >>= 16; + r += 16; + } + if (!(x & 0xff)) { + x >>= 8; + r += 8; + } + if (!(x & 0xf)) { + x >>= 4; + r += 4; + } + if (!(x & 3)) { + x >>= 2; + r += 2; + } + if (!(x & 1)) { + x >>= 1; + r += 1; + } + return r; +} + +#endif /* _ASM_GENERIC_BITOPS_FFS_H_ */ diff --git a/include/asm-generic/bitops/fls.h b/include/asm-generic/bitops/fls.h new file mode 100644 index 0000000..850859b --- /dev/null +++ b/include/asm-generic/bitops/fls.h @@ -0,0 +1,41 @@ +#ifndef _ASM_GENERIC_BITOPS_FLS_H_ +#define _ASM_GENERIC_BITOPS_FLS_H_ + +/** + * fls - find last (most-significant) bit set + * @x: the word to search + * + * This is defined the same way as ffs. + * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32. + */ + +static inline int fls(int x) +{ + int r = 32; + + if (!x) + return 0; + if (!(x & 0xffff0000u)) { + x <<= 16; + r -= 16; + } + if (!(x & 0xff000000u)) { + x <<= 8; + r -= 8; + } + if (!(x & 0xf0000000u)) { + x <<= 4; + r -= 4; + } + if (!(x & 0xc0000000u)) { + x <<= 2; + r -= 2; + } + if (!(x & 0x80000000u)) { + x <<= 1; + r -= 1; + } + return r; +} + +#endif /* _ASM_GENERIC_BITOPS_FLS_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..31d4d4d 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -129,6 +129,32 @@ static inline unsigned int generic_hweight8(unsigned int w) # define fls generic_fls #endif
+static inline unsigned fls_long(unsigned long l) +{ + if (sizeof(l) == 4) + return fls(l); + return fls64(l); +} + +/** + * __ffs64 - find first set bit in a 64 bit word + * @word: The 64 bit word + * + * On 64 bit arches this is a synomyn for __ffs + * The result is not defined if no bits are set, so check that @word + * is non-zero before calling this. + */ +static inline unsigned long __ffs64(u64 word) +{ +#if BITS_PER_LONG == 32 + if (((u32)word) == 0UL) + return __ffs((u32)(word >> 32)) + 32; +#elif BITS_PER_LONG != 64 +#error BITS_PER_LONG not 32 or 64 +#endif + return __ffs((unsigned long)word); +} + /** * __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..aa1de63 --- /dev/null +++ b/include/linux/log2.h @@ -0,0 +1,205 @@ +/* Integer base 2 logarithm calculation + * + * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +#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 */