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author | Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> | 2023-04-24 22:03:06 +0200 |
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committer | GitHub <noreply@github.com> | 2023-04-24 22:03:06 +0200 |
commit | 208a59c15fd41f87248a1a981e558acd3de5e47b (patch) | |
tree | 45f73492212a2c220305ab41bb3c74cd6265efeb /src/fundamental | |
parent | 91ce42f008764c3c6d8d72c5fb3b72d0945b7de2 (diff) | |
parent | 2ed7a221fafb25eea937c4e86fb88ee501dba51e (diff) | |
download | systemd-208a59c15fd41f87248a1a981e558acd3de5e47b.tar.gz |
Merge pull request #27113 from keszybz/variable-expansion-rework
Rework serialization of command lines in pid1 and make run not expand variables
Diffstat (limited to 'src/fundamental')
-rw-r--r-- | src/fundamental/logarithm.h | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/src/fundamental/logarithm.h b/src/fundamental/logarithm.h new file mode 100644 index 0000000000..0b03bbded1 --- /dev/null +++ b/src/fundamental/logarithm.h @@ -0,0 +1,59 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +#pragma once + +#include <stdint.h> + +/* Note: log2(0) == log2(1) == 0 here and below. */ + +#define CONST_LOG2ULL(x) ((x) > 1 ? (unsigned) __builtin_clzll(x) ^ 63U : 0) +#define NONCONST_LOG2ULL(x) ({ \ + unsigned long long _x = (x); \ + _x > 1 ? (unsigned) __builtin_clzll(_x) ^ 63U : 0; \ + }) +#define LOG2ULL(x) __builtin_choose_expr(__builtin_constant_p(x), CONST_LOG2ULL(x), NONCONST_LOG2ULL(x)) + +static inline unsigned log2u64(uint64_t x) { +#if __SIZEOF_LONG_LONG__ == 8 + return LOG2ULL(x); +#else +# error "Wut?" +#endif +} + +static inline unsigned u32ctz(uint32_t n) { +#if __SIZEOF_INT__ == 4 + return n != 0 ? __builtin_ctz(n) : 32; +#else +# error "Wut?" +#endif +} + +#define popcount(n) \ + _Generic((n), \ + unsigned char: __builtin_popcount(n), \ + unsigned short: __builtin_popcount(n), \ + unsigned: __builtin_popcount(n), \ + unsigned long: __builtin_popcountl(n), \ + unsigned long long: __builtin_popcountll(n)) + +#define CONST_LOG2U(x) ((x) > 1 ? __SIZEOF_INT__ * 8 - __builtin_clz(x) - 1 : 0) +#define NONCONST_LOG2U(x) ({ \ + unsigned _x = (x); \ + _x > 1 ? __SIZEOF_INT__ * 8 - __builtin_clz(_x) - 1 : 0; \ + }) +#define LOG2U(x) __builtin_choose_expr(__builtin_constant_p(x), CONST_LOG2U(x), NONCONST_LOG2U(x)) + +static inline unsigned log2i(int x) { + return LOG2U(x); +} + +static inline unsigned log2u(unsigned x) { + return LOG2U(x); +} + +static inline unsigned log2u_round_up(unsigned x) { + if (x <= 1) + return 0; + + return log2u(x - 1) + 1; +} |