diff options
| author | Explorer09 <explorer09@gmail.com> | 2017-02-12 19:59:52 +0800 |
|---|---|---|
| committer | Will Estes <westes575@gmail.com> | 2017-02-16 13:26:21 -0500 |
| commit | c7a545ae0907c81cf52139dd391659586570f60c (patch) | |
| tree | edf686d64f473abea392aee425521a22116d9f11 /src/flexdef.h | |
| parent | 122e58965acaf67386d1fc6893f069bd27e5aa26 (diff) | |
scanner: compute powers of two faster.
Replace the naive "for" loop in determining power of two with a clever
bitwise solution. This code is around the Internet already and is in
Public Domain.
Diffstat (limited to 'src/flexdef.h')
| -rw-r--r-- | src/flexdef.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/src/flexdef.h b/src/flexdef.h index 97aec14..e5ab8e0 100644 --- a/src/flexdef.h +++ b/src/flexdef.h @@ -109,6 +109,8 @@ #define ABS(x) ((x) < 0 ? -(x) : (x)) #endif +/* Whether an integer is a power of two */ +#define is_power_of_2(n) ((n) > 0 && ((n) & ((n) - 1)) == 0) #define unspecified -1 |