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commit 8ef9117924709b0ce013b5f5d2db5bb7fe41b987
parent ea69f17d989784f75433eb69de0ad2dbe6c7195a
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date:   Mon, 31 Mar 2014 15:38:01 -0300

fancier way to do sign extension

Diffstat:
Mlstrlib.c | 7+++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/lstrlib.c b/lstrlib.c @@ -1,5 +1,5 @@ /* -** $Id: lstrlib.c,v 1.189 2014/03/21 14:26:44 roberto Exp roberto $ +** $Id: lstrlib.c,v 1.190 2014/03/27 15:58:05 roberto Exp roberto $ ** Standard library for string operations and pattern-matching ** See Copyright Notice in lua.h */ @@ -1049,9 +1049,8 @@ static int unpackint (const char *buff, lua_Integer *res, n |= (lua_Integer)(unsigned char)buff[littleendian ? size - 1 - i : i]; } if (size < SZINT) { /* need sign extension? */ - lua_Integer mask = (~(lua_Integer)0) << (size*NB - 1); - if (n & mask) /* negative value? */ - n |= mask; /* signal extension */ + lua_Unsigned mask = (lua_Unsigned)1 << (size*NB - 1); + n = (lua_Integer)((n ^ mask) - mask); /* do sign extension */ } *res = n; return 1;