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document clz64/log2u64 not being able to handle 0

pull/187/head
Daniel Micay 2022-01-16 16:28:24 -05:00
parent 81cf2f27a0
commit 3e312695e1
1 changed files with 6 additions and 4 deletions
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10
util.h
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@ -37,14 +37,16 @@ typedef unsigned __int128 u128;
#define U64_WIDTH 64 #define U64_WIDTH 64
static inline int clz64(u64 x) {
return __builtin_clzll(x);
}
static inline int ffz64(u64 x) { static inline int ffz64(u64 x) {
return __builtin_ffsll(~x); return __builtin_ffsll(~x);
} }
// parameter must not be 0
static inline int clz64(u64 x) {
return __builtin_clzll(x);
}
// parameter must not be 0
static inline u64 log2u64(u64 x) { static inline u64 log2u64(u64 x) {
return U64_WIDTH - clz64(x) - 1; return U64_WIDTH - clz64(x) - 1;
} }