Change PL_screamnext to store absolute positions.

PL_screamnext gives the position of the next occurrence of the current octet.
Previously it stored this as an offset from the current position, with -pos
stored for "no more", so that the calculated new offset would be zero,
allowing a zero/non-zero loop exit test in Perl_screaminstr().

Now it stores absolute position, with -1 for "no more". Also codify -1 as the
"not present" value for PL_screamfirst, instead of any negative value.

1 files changed, 2 insertions, 2 deletions

diff --git a/pp.c b/pp.c
index c72ce28862..61e9dc10e4 100644
--- a/pp.c
+++ b/pp.c
@@ -762,9 +762,9 @@ PP(pp_study)
     while (--pos >= 0) {
 	register const I32 ch = s[pos];
 	if (sfirst[ch] >= 0)
-	    snext[pos] = sfirst[ch] - pos;
+	    snext[pos] = sfirst[ch];
 	else
-	    snext[pos] = -pos;
+	    snext[pos] = -1;
 	sfirst[ch] = pos;
     }