+ different fix for Pack/Unpack2 (works as for floats)

Author: skirpichev

Lib/test/test_struct.py

@@ -935,9 +935,8 @@ def test_half_float(self):
             self.assertTrue(math.isnan(struct.unpack('<e', bits)[0]))
             self.assertTrue(math.isnan(struct.unpack('>e', bits[::-1])[0]))
 
-        # Check round-trip for NaN's:
-        if sys.platform != 'win32':
-            for formatcode, bits in format_bits__nan_list:
+            if sys.platform != 'win32':
+                # Check round-trip for NaN's:
                 nan = struct.unpack('<e', bits)[0]
                 self.assertEqual(struct.pack('<e', nan), bits)
                 nan = struct.unpack('>e', bits[::-1])[0]

Objects/floatobject.c

@@ -2054,10 +2054,7 @@ PyFloat_Pack2(double x, char *data, int le)
         uint64_t v;
 
         memcpy(&v, &x, sizeof(v));
-        bits = v & 0x1ffULL; /* NaN's payload */
-        if (v & 0x8000000000000ULL) { /* is a quiet NaN? */
-            bits += 0x200;
-        }
+        bits = ((v & 0xffc0000000000ULL)>>42); /* NaN's payload */
     }
     else {
         sign = (x < 0.0);
@@ -2416,11 +2413,7 @@ PyFloat_Unpack2(const char *data, int le)
             /* NaN */
             uint64_t v = sign ? 0xfff0000000000000ULL : 0x7ff0000000000000ULL;
 
-            if (f & 0x200) { /* is a quiet NaN? */
-                v += 0x8000000000000ULL;
-                f -= 0x200;
-            }
-            v += f; /* add NaN's payload */
+            v += ((uint64_t)f << 42); /* add NaN's payload */
             memcpy(&x, &v, sizeof(v));
             return x;
         }