From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Fri, 5 May 2017 02:59:18 +0000 (-0400)
Subject: Add utils_get_count_order_u64 to utils
X-Git-Tag: v2.10.0-rc1~45
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=db5be0a3dcf30edeca9c3143682454bab9523f71;p=lttng-tools.git

Add utils_get_count_order_u64 to utils

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/common/utils.c b/src/common/utils.c
index 16d2f817a..4d49728c0 100644
--- a/src/common/utils.c
+++ b/src/common/utils.c
@@ -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.
diff --git a/src/common/utils.h b/src/common/utils.h
index 7285f5c30..0daf5b98d 100644
--- a/src/common/utils.h
+++ b/src/common/utils.h
@@ -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);