From dd92a09ecac74760823b047c074e4b21a8cb531f Mon Sep 17 00:00:00 2001
From: Rich Felker <dalias@aerifal.cx>
Date: Mon, 25 Jul 2011 09:21:40 -0400
Subject: comment non-obvious de bruijn sequence code in int parser

---
 src/internal/intparse.c | 2 ++
 1 file changed, 2 insertions(+)

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;
-- 
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