Add raw_ctz64(), ctz64(), and popcount64() using builtins when
available.
I'm not sure if the "UINT64_MAX == ~0UL" and "UINT64_MAX == ~0ULL"
work in all cases as I imagine they would.
Signed-off-by: Jarno Rajahalme <jrajaha...@nicira.com>
---
lib/util.h | 51 +++++++++++++++++++++++++++++++++++++---
tests/test-util.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++------
2 files changed, 108 insertions(+), 10 deletions(-)
diff --git a/lib/util.h b/lib/util.h
index 32a7c8c..62dc3ae 100644
--- a/lib/util.h
+++ b/lib/util.h
@@ -283,6 +283,10 @@ void ignore(bool x OVS_UNUSED);
/* Bitwise tests. */
+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'. Undefined if 'n' == 0.
*
* This compiles to a single machine instruction ("bsf") with GCC on x86. */
@@ -299,6 +303,44 @@ raw_ctz(uint32_t n)
int raw_ctz(uint32_t n);
#endif
+#if !defined(UINT_MAX) || !defined(UINT64_MAX)
+#error "Someone screwed up the #includes."
+#elif __GNUC__ >= 4 && UINT64_MAX == ~0UL
+static inline int
+raw_ctz64(uint64_t n)
+{
+ return __builtin_ctzl(n);
+}
+static inline int
+popcount64(uint64_t n)
+{
+ return __builtin_popcountl(n);
+}
+#elif __GNUC__ >= 4 && UINT64_MAX == ~0ULL
+static inline int
+raw_ctz64(uint64_t n)
+{
+ return __builtin_ctzll(n);
+}
+static inline int
+popcount64(uint64_t n)
+{
+ return __builtin_popcountll(n);
+}
+#else
+/* Defined using the 32-bit counterparts. */
+static inline int
+raw_ctz64(uint64_t n)
+{
+ return (uint32_t)n ? raw_ctz(n) : 32 + raw_ctz(n >> 32);
+}
+static inline int
+popcount64(uint64_t n)
+{
+ return popcount(n) + popcount(n >> 32);
+}
+#endif
+
/* Returns the number of trailing 0-bits in 'n', or 32 if 'n' is 0. */
static inline int
ctz(uint32_t n)
@@ -306,9 +348,12 @@ ctz(uint32_t n)
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_ctz64(n) : 64;
+}
/* Returns the rightmost 1-bit in 'x' (e.g. 01011000 => 00001000), or 0 if 'x'
* is 0. */
diff --git a/tests/test-util.c b/tests/test-util.c
index 6ed2f77..4f5b78c 100644
--- a/tests/test-util.c
+++ b/tests/test-util.c
@@ -71,6 +71,16 @@ check_ctz(uint32_t x, int n)
}
static void
+check_ctz64(uint64_t x, int n)
+{
+ if (ctz64(x) != n) {
+ fprintf(stderr, "ctz64(%"PRIu64") is %d but should be %d\n",
+ x, ctz64(x), n);
+ abort();
+ }
+}
+
+static void
test_ctz(int argc OVS_UNUSED, char *argv[] OVS_UNUSED)
{
int n;
@@ -86,8 +96,21 @@ test_ctz(int argc OVS_UNUSED, char *argv[] OVS_UNUSED)
check_ctz((random_uint32() | 1) << n, n);
}
+
+ for (n = 0; n < 64; n++) {
+ /* Check minimum x such that f(x) == n. */
+ check_ctz64(UINT64_C(1) << n, n);
+
+ /* Check maximum x such that f(x) == n. */
+ check_ctz64(UINT64_MAX << n, n);
+
+ /* Check a random value in the middle. */
+ check_ctz64((random_uint64() | UINT64_C(1)) << n, n);
+ }
+
/* Check ctz(0). */
check_ctz(0, 32);
+ check_ctz64(0, 64);
}
/* Returns a random number in the range 'min'...'max' inclusive. */
@@ -154,11 +177,11 @@ test_round_down_pow2(int argc OVS_UNUSED, char *argv[]
OVS_UNUSED)
}
static void
-shuffle(unsigned int *p, size_t n)
+shuffle(uint64_t *p, size_t n)
{
for (; n > 1; n--, p++) {
- unsigned int *q = &p[random_range(n)];
- unsigned int tmp = *p;
+ uint64_t *q = &p[random_range(n)];
+ uint64_t tmp = *p;
*p = *q;
*q = tmp;
}
@@ -175,35 +198,65 @@ check_popcount(uint32_t x, int n)
}
static void
+check_popcount64(uint64_t x, int n)
+{
+ if (popcount64(x) != n) {
+ fprintf(stderr, "popcount64(%#"PRIx64") is %d but should be %d\n",
+ x, popcount64(x), n);
+ abort();
+ }
+}
+
+static void
test_popcount(int argc OVS_UNUSED, char *argv[] OVS_UNUSED)
{
- unsigned int bits[32];
+ uint64_t bits[64];
int i;
for (i = 0; i < ARRAY_SIZE(bits); i++) {
- bits[i] = 1u << i;
+ bits[i] = UINT64_C(1) << i;
}
check_popcount(0, 0);
+ check_popcount64(0, 0);
for (i = 0; i < 1000; i++) {
uint32_t x = 0;
int j;
- shuffle(bits, ARRAY_SIZE(bits));
+ shuffle(bits, ARRAY_SIZE(bits)/2);
for (j = 0; j < 32; j++) {
x |= bits[j];
check_popcount(x, j + 1);
}
assert(x == UINT32_MAX);
- shuffle(bits, ARRAY_SIZE(bits));
+ shuffle(bits, ARRAY_SIZE(bits)/2);
for (j = 31; j >= 0; j--) {
x &= ~bits[j];
check_popcount(x, j);
}
assert(x == 0);
}
+
+ for (i = 0; i < 1000; i++) {
+ uint64_t x = 0;
+ int j;
+
+ shuffle(bits, ARRAY_SIZE(bits));
+ for (j = 0; j < 64; j++) {
+ x |= bits[j];
+ check_popcount64(x, j + 1);
+ }
+ assert(x == UINT64_MAX);
+
+ shuffle(bits, ARRAY_SIZE(bits));
+ for (j = 63; j >= 0; j--) {
+ x &= ~bits[j];
+ check_popcount64(x, j);
+ }
+ assert(x == 0);
+ }
}
/* Returns the sum of the squares of the first 'n' positive integers. */
--
1.7.10.4
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