support ld80 pseudo-denormal invalid bit patterns; treat them as nan

this is silly, but it makes apps that read binary junk and interpret
it as ld80 "safer", and it gets gnulib to stop replacing printf...

diff --git a/src/math/__fpclassifyl.c b/src/math/__fpclassifyl.c
index a5ad36f..e4d231b 100644 (file)
--- a/src/math/__fpclassifyl.c
+++ b/src/math/__fpclassifyl.c
@@ -7,8 +7,11 @@ int __fpclassifyl(long double x)
 {
        union ldshape u = { x };
        int e = u.bits.exp;
-       if (!e)
-               return u.bits.m ? FP_SUBNORMAL : FP_ZERO;
+       if (!e) {
+               if (u.bits.m >> 63) return FP_NAN;
+               else if (u.bits.m) return FP_SUBNORMAL;
+               else return FP_ZERO;
+       }
        if (e == 0x7fff)
                return u.bits.m & (uint64_t)-1>>1 ? FP_NAN : FP_INFINITE;
        return u.bits.m & (uint64_t)1<<63 ? FP_NORMAL : FP_NAN;