Add utils_get_count_order_u64 to utils
authorJérémie Galarneau <jeremie.galarneau@efficios.com>
Fri, 5 May 2017 02:59:18 +0000 (22:59 -0400)
committerJérémie Galarneau <jeremie.galarneau@efficios.com>
Fri, 5 May 2017 04:15:01 +0000 (00:15 -0400)
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
src/common/utils.c
src/common/utils.h

index 16d2f817ad8a1b21d99228a67e5bba25e0d1f3fa..4d49728c0f47a23cce6eba1bc2f72f11c2c14836 100644 (file)
@@ -1017,6 +1017,59 @@ static inline unsigned int fls_u32(uint32_t x)
 #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)
 {
@@ -1063,6 +1116,20 @@ int utils_get_count_order_u32(uint32_t x)
        return fls_u32(x - 1);
 }
 
+/*
+ * Return the minimum order for which x <= (1UL << order).
+ * Return -1 if x is 0.
+ */
+LTTNG_HIDDEN
+int utils_get_count_order_u64(uint64_t x)
+{
+       if (!x) {
+               return -1;
+       }
+
+       return fls_u64(x - 1);
+}
+
 /**
  * Obtain the value of LTTNG_HOME environment variable, if exists.
  * Otherwise returns the value of HOME.
index 7285f5c3032932ec03531ddb7ef7973f403fbc6b..0daf5b98df70d7add96b6a7fda2fac53e85ad681 100644 (file)
@@ -48,6 +48,7 @@ int utils_rotate_stream_file(char *path_name, char *file_name, uint64_t size,
                int *stream_fd);
 int utils_parse_size_suffix(char const * const str, uint64_t * const size);
 int utils_get_count_order_u32(uint32_t x);
+int utils_get_count_order_u64(uint64_t x);
 char *utils_get_home_dir(void);
 char *utils_get_user_home_dir(uid_t uid);
 char *utils_get_kmod_probes_list(void);
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