From 8ce58badbfbff17e050194e01a9120ac6058bc1c Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Thu, 2 May 2013 11:33:46 -0400 Subject: [PATCH] Implement get_count_order in lttng utils Imported from Userspace RCU rculfhash.c. Signed-off-by: Mathieu Desnoyers --- src/bin/lttng/utils.c | 152 ++++++++++++++++++++++++++++++++++++++++++ src/bin/lttng/utils.h | 18 +++++ 2 files changed, 170 insertions(+) diff --git a/src/bin/lttng/utils.c b/src/bin/lttng/utils.c index b7f5170aa..94c4527d9 100644 --- a/src/bin/lttng/utils.c +++ b/src/bin/lttng/utils.c @@ -77,3 +77,155 @@ void list_cmd_options(FILE *ofp, struct poptOption *options) } } } + +/* + * fls: returns the position of the most significant bit. + * Returns 0 if no bit is set, else returns the position of the most + * significant bit (from 1 to 32 on 32-bit, from 1 to 64 on 64-bit). + */ +#if defined(__i386) || defined(__x86_64) +static inline +unsigned int fls_u32(uint32_t x) +{ + int r; + + asm("bsrl %1,%0\n\t" + "jnz 1f\n\t" + "movl $-1,%0\n\t" + "1:\n\t" + : "=r" (r) : "rm" (x)); + return r + 1; +} +#define HAS_FLS_U32 +#endif + +#if defined(__x86_64) +static inline +unsigned int fls_u64(uint64_t x) +{ + long r; + + asm("bsrq %1,%0\n\t" + "jnz 1f\n\t" + "movq $-1,%0\n\t" + "1:\n\t" + : "=r" (r) : "rm" (x)); + return r + 1; +} +#define HAS_FLS_U64 +#endif + +#ifndef HAS_FLS_U64 +static __attribute__((unused)) +unsigned int fls_u64(uint64_t x) +{ + unsigned int r = 64; + + if (!x) + return 0; + + if (!(x & 0xFFFFFFFF00000000ULL)) { + x <<= 32; + r -= 32; + } + if (!(x & 0xFFFF000000000000ULL)) { + x <<= 16; + r -= 16; + } + if (!(x & 0xFF00000000000000ULL)) { + x <<= 8; + r -= 8; + } + if (!(x & 0xF000000000000000ULL)) { + x <<= 4; + r -= 4; + } + if (!(x & 0xC000000000000000ULL)) { + x <<= 2; + r -= 2; + } + if (!(x & 0x8000000000000000ULL)) { + x <<= 1; + r -= 1; + } + return r; +} +#endif + +#ifndef HAS_FLS_U32 +static __attribute__((unused)) +unsigned int fls_u32(uint32_t x) +{ + unsigned 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 + +static +unsigned int fls_ulong(unsigned long x) +{ +#if (CAA_BITS_PER_LONG == 32) + return fls_u32(x); +#else + return fls_u64(x); +#endif +} + +/* + * Return the minimum order for which x <= (1UL << order). + * Return -1 if x is 0. + */ +int get_count_order_u32(uint32_t x) +{ + if (!x) + return -1; + + return fls_u32(x - 1); +} + +/* + * Return the minimum order for which x <= (1UL << order). + * Return -1 if x is 0. + */ +int get_count_order_u64(uint64_t x) +{ + if (!x) + return -1; + + return fls_u64(x - 1); +} + +/* + * Return the minimum order for which x <= (1UL << order). + * Return -1 if x is 0. + */ +int get_count_order_ulong(unsigned long x) +{ + if (!x) + return -1; + + return fls_ulong(x - 1); +} diff --git a/src/bin/lttng/utils.h b/src/bin/lttng/utils.h index 9f7bfcca1..57bec1250 100644 --- a/src/bin/lttng/utils.h +++ b/src/bin/lttng/utils.h @@ -23,4 +23,22 @@ char *get_session_name(void); void list_cmd_options(FILE *ofp, struct poptOption *options); +/* + * Return the minimum order for which x <= (1UL << order). + * Return -1 if x is 0. + */ +int get_count_order_u32(uint32_t x); + +/* + * Return the minimum order for which x <= (1UL << order). + * Return -1 if x is 0. + */ +int get_count_order_u64(uint64_t x); + +/* + * Return the minimum order for which x <= (1UL << order). + * Return -1 if x is 0. + */ +int get_count_order_ulong(unsigned long x); + #endif /* _LTTNG_UTILS_H */ -- 2.34.1