\f
/* Bitwise tests. */
-/* Returns the number of trailing 0-bits in 'n'. Undefined if 'n' == 0.
- *
- * This compiles to a single machine instruction ("bsf") with GCC on x86. */
-#if !defined(UINT_MAX) || !defined(UINT32_MAX)
-#error "Someone screwed up the #includes."
-#elif __GNUC__ >= 4 && UINT_MAX == UINT32_MAX
+int log_2_floor(uint32_t);
+int log_2_ceil(uint32_t);
+unsigned int count_1bits(uint64_t);
+
+/* Returns the number of trailing 0-bits in 'n'. Undefined if 'n' == 0. */
+#if __GNUC__ >= 4
static inline int
-raw_ctz(uint32_t n)
+raw_ctz(uint64_t n)
{
- return __builtin_ctz(n);
+ /* With GCC 4.7 on 32-bit x86, if a 32-bit integer is passed as 'n', using
+ * a plain __builtin_ctzll() here always generates an out-of-line function
+ * call. The test below helps it to emit a single 'bsf' instruction. */
+ return (__builtin_constant_p(n <= UINT32_MAX) && n <= UINT32_MAX
+ ? __builtin_ctz(n)
+ : __builtin_ctzll(n));
}
#else
/* Defined in util.c. */
-int raw_ctz(uint32_t n);
+int raw_ctz(uint64_t n);
#endif
/* Returns the number of trailing 0-bits in 'n', or 32 if 'n' is 0. */
return n ? raw_ctz(n) : 32;
}
-int log_2_floor(uint32_t);
-int log_2_ceil(uint32_t);
-unsigned int popcount(uint32_t);
+/* Returns the number of trailing 0-bits in 'n', or 64 if 'n' is 0. */
+static inline int
+ctz64(uint64_t n)
+{
+ return n ? raw_ctz(n) : 64;
+}
/* Returns the rightmost 1-bit in 'x' (e.g. 01011000 => 00001000), or 0 if 'x'
* is 0. */