Backport: Port dynamic buffer to stable 2.9
[lttng-tools.git] / src / common / utils.c
index 24c3b8ca146ff1fafe8de8da3dd059c7f947f415..25d510854f972438085c98a8b6f41fd06001bf47 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.
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