From: Rich Felker <dalias@aerifal.cx>
Date: Mon, 25 Jul 2011 13:21:40 +0000 (-0400)
Subject: comment non-obvious de bruijn sequence code in int parser
X-Git-Tag: v0.8.0~84
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=dd92a09ecac74760823b047c074e4b21a8cb531f;p=oweals%2Fmusl.git

comment non-obvious de bruijn sequence code in int parser
---

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;