fix the last known rounding bug in floating point printing

[musl] / src / stdio / vfprintf.c

diff --git a/src/stdio/vfprintf.c b/src/stdio/vfprintf.c
index f19058d..f13fbe1 100644 (file)
--- a/src/stdio/vfprintf.c
+++ b/src/stdio/vfprintf.c
@@ -326,9 +326,10 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
                if (x || d+1!=z) {
                        long double round = CONCAT(0x1p,LDBL_MANT_DIG);
                        long double small;
-                       if (x<i/2) small=0x01p-1;
-                       else if (i==i/2 && d+1==z) small=0x10p-1;
-                       else small=0x11p-1;
+                       if (*d/i & 1) round += 2;
+                       if (x<i/2) small=0x0.8p0;
+                       else if (x==i/2 && d+1==z) small=0x1.0p0;
+                       else small=0x1.8p0;
                        if (pl && *prefix=='-') round*=-1, small*=-1;
                        *d -= x;
                        /* Decide whether to round by probing round+small */