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| author | Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> | 2023-04-03 14:32:39 +0200 |
|---|---|---|
| committer | Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> | 2023-04-24 10:02:30 +0200 |
| commit | a12bc99ef0fc04fa48767c891f7a6db6404e51d5 (patch) | |
| tree | f5840c3081c8aea6cddd557635313a2ab2d426a4 /src/test | |
| parent | 6eccc3cfa9dcfea3c8b508a66d2d592e6b9fcb93 (diff) | |
| download | systemd-a12bc99ef0fc04fa48767c891f7a6db6404e51d5.tar.gz | |
basic/logarithm: add popcount() wrapper
__builtin_popcount() is a bit of a mouthful, so let's provide a helper.
Using _Generic has the advantage that if a type other then the ones on
the list is given, compilation will fail. This is nice, because if by any
change we pass a wider type, it is rejected immediately instead of being
truncated.
log.h is also needed. It is included transitively, but let's include it
directly.
macro.h is *not* needed.
Diffstat (limited to 'src/test')
| -rw-r--r-- | src/test/test-logarithm.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/src/test/test-logarithm.c b/src/test/test-logarithm.c index b6818b422c..b35fea9c27 100644 --- a/src/test/test-logarithm.c +++ b/src/test/test-logarithm.c @@ -71,4 +71,25 @@ TEST(log2i) { assert_se(log2i(INT_MAX) == sizeof(int)*8-2); } +TEST(popcount) { + uint16_t u16a = 0x0000; + uint16_t u16b = 0xFFFF; + uint32_t u32a = 0x00000010; + uint32_t u32b = 0xFFFFFFFF; + uint64_t u64a = 0x0000000000000010; + uint64_t u64b = 0x0100000000100010; + + assert_se(popcount(u16a) == 0); + assert_se(popcount(u16b) == 16); + assert_se(popcount(u32a) == 1); + assert_se(popcount(u32b) == 32); + assert_se(popcount(u64a) == 1); + assert_se(popcount(u64b) == 3); + + /* This would fail: + * error: ‘_Generic’ selector of type ‘int’ is not compatible with any association + * assert_se(popcount(0x10) == 1); + */ +} + DEFINE_TEST_MAIN(LOG_INFO); |