- union ldshape u = { x };
- int e = u.bits.exp;
- if (!e) {
- if (u.bits.m >> 63) return FP_NAN;
- else if (u.bits.m) return FP_SUBNORMAL;
- else return FP_ZERO;
+ union ldshape u = {x};
+ int e = u.i.se & 0x7fff;
+ int msb = u.i.m>>63;
+ if (!e && !msb)
+ return u.i.m ? FP_SUBNORMAL : FP_ZERO;
+ if (e == 0x7fff) {
+ /* The x86 variant of 80-bit extended precision only admits
+ * one representation of each infinity, with the mantissa msb
+ * necessarily set. The version with it clear is invalid/nan.
+ * The m68k variant, however, allows either, and tooling uses
+ * the version with it clear. */
+ if (__BYTE_ORDER == __LITTLE_ENDIAN && !msb)
+ return FP_NAN;
+ return u.i.m << 1 ? FP_NAN : FP_INFINITE;