Fix: poll compat layer reallocation new size

[lttng-tools.git] / src / common / utils.c

diff --git a/src/common/utils.c b/src/common/utils.c
index f3718f00fa8ddabb7c921ac55287626dd83f45b8..38f78a7e8e7d40cd6fcebefd297e5bb240c52aaf 100644 (file)
--- a/src/common/utils.c
+++ b/src/common/utils.c
@@ -440,7 +440,7 @@ static void regex_print_error(int errcode, regex_t *regex)
  *
  * @param str  The string to parse.
  * @param size Pointer to a size_t that will be filled with the
- *             resulting size.
+ *             resulting size.
  *
  * @return 0 on success, -1 on failure.
  */
@@ -518,3 +518,69 @@ free:
 end:
        return ret;
 }
+
+/*
+ * 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
+
+#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
+
+/*
+ * Return the minimum order for which x <= (1UL << order).
+ * Return -1 if x is 0.
+ */
+LTTNG_HIDDEN
+int utils_get_count_order_u32(uint32_t x)
+{
+       if (!x) {
+               return -1;
+       }
+
+       return fls_u32(x - 1);
+}