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| author | Rich Felker <dalias@aerifal.cx> | 2011-07-25 09:21:40 -0400 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2011-07-25 09:21:40 -0400 |
| commit | dd92a09ecac74760823b047c074e4b21a8cb531f (patch) | |
| tree | ea115f59b02f3a691107a2a7440016b5a3050abd | |
| parent | 427173b9325d604d30650c16f1774942130aec52 (diff) | |
| download | musl-dd92a09ecac74760823b047c074e4b21a8cb531f.tar.gz | |
comment non-obvious de bruijn sequence code in int parser
| -rw-r--r-- | src/internal/intparse.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/src/internal/intparse.c b/src/internal/intparse.c index fd403b58..90aa8339 100644 --- a/src/internal/intparse.c +++ b/src/internal/intparse.c @@ -70,6 +70,8 @@ int __intparse(struct intparse *v, const void *buf, size_t n) for (; n && *s-'0'<10U && v->small<=SLIM; n--, s++) v->small = v->small * 10 + (*s-'0'); } else if ((b&-b) == b) { + /* Compute bitshift for power-of-two bases + * using a De Bruijn B(2,3) sequence. */ int bs = "\0\1\2\4\7\3\6\5"[(0x17*b)>>5&7]; for (; n && (d=digits[*s])<b && v->small<=SLIM; n--, s++) v->small = (v->small<<bs) + d; |