cleanup and comments

python · vstinner · Apr 28, 2025 · Feb 22, 2025 · Feb 25, 2025 · Feb 25, 2025
commit c7c08ff62fdcc53d2b9e0325b4b49dedf33b51b0
diff --git a/Objects/floatobject.c b/Objects/floatobject.c
@@ -2054,7 +2054,7 @@
         uint64_t v;
 
         memcpy(&v, &x, sizeof(v));
-        bits = ((v & 0xffc0000000000ULL)>>42); /* NaN's payload */
+        bits = (v & 0xffc0000000000ULL) >> 42; /* NaN's payload */
     }
     else {
         sign = (x < 0.0);
@@ -2218,14 +2218,15 @@
         if (isinf(y) && !isinf(x))
             goto Overflow;
 
+        /* correct y if x was a sNaN, transformed to qNaN by assignment */
         if (isnan(x)) {
             uint64_t v;
 
             memcpy(&v, &x, 8);
-            if ((v & (1ULL<<51)) == 0) {
+            if ((v & (1ULL << 51)) == 0) {
                 uint32_t *py = (uint32_t *)&y;
 
-                *py -= (1<<22);
+                *py -= 1 << 22; /* make sNaN */
             }
         }
 
@@ -2413,7 +2414,7 @@
             /* NaN */
             uint64_t v = sign ? 0xfff0000000000000ULL : 0x7ff0000000000000ULL;
 
-            v += ((uint64_t)f << 42); /* add NaN's payload */
+            v += (uint64_t)f << 42; /* add NaN's payload */
             memcpy(&x, &v, sizeof(v));
             return x;
         }
@@ -2511,15 +2512,16 @@
             memcpy(&x, p, 4);
         }
 
+        /* return sNaN double if x was sNaN float */
         if (isnan(x)) {
             uint32_t v;
 
             memcpy(&v, &x, 4);
             if ((v & (1<<22)) == 0) {
-                double y = x;
+                double y = x; /* will make qNaN double */
                 uint64_t *py = (uint64_t *)&y;
 
-                *py -= (1ULL<<51);
+                *py -= (1ULL<<51); /* make sNaN */
                 return y;
             }
         }