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| author | Lennart Poettering <lennart@poettering.net> | 2022-08-05 13:16:27 +0200 |
|---|---|---|
| committer | Lennart Poettering <lennart@poettering.net> | 2022-08-05 13:34:11 +0200 |
| commit | c51e4c796d53f370750b27768fc979f6aa0cb263 (patch) | |
| tree | 9cced2e8886c881d4af1ad37c1da0d1c7666fb65 /src/fundamental | |
| parent | 14e7bc2e77d2699498a1f74d7e4f905f11eca335 (diff) | |
| download | systemd-c51e4c796d53f370750b27768fc979f6aa0cb263.tar.gz | |
macro: add macro for checking if integer is power of 2
Diffstat (limited to 'src/fundamental')
| -rw-r--r-- | src/fundamental/macro-fundamental.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/src/fundamental/macro-fundamental.h b/src/fundamental/macro-fundamental.h index e5f6dc7f8c..5c67d3e2f7 100644 --- a/src/fundamental/macro-fundamental.h +++ b/src/fundamental/macro-fundamental.h @@ -200,6 +200,19 @@ MIN(_c, z); \ }) +/* Returns true if the passed integer is a positive power of two */ +#define CONST_ISPOWEROF2(x) \ + ((x) > 0 && ((x) & ((x) - 1)) == 0) + +#define ISPOWEROF2(x) \ + __builtin_choose_expr( \ + __builtin_constant_p(x), \ + CONST_ISPOWEROF2(x), \ + ({ \ + const typeof(x) _x = (x); \ + CONST_ISPOWEROF2(_x); \ + })) + #define LESS_BY(a, b) __LESS_BY(UNIQ, (a), UNIQ, (b)) #define __LESS_BY(aq, a, bq, b) \ ({ \ |