find the exact lower bound causes overflow

Author: Arzaghi

stl/inc/random

@@ -188,8 +188,11 @@ public:
             for (_Kx = 0; _Kx < _Mx; ++_Kx) { // scramble and add any vector contributions
                 result_type _Rx1 =
                     1664525 * _Xor27(_UFirst[_Kx % _Nx] ^ _UFirst[(_Kx + _Px) % _Nx] ^ _UFirst[(_Kx - 1) % _Nx]);
-                result_type _Rx2 = static_cast<result_type>(
-                    (_Rx1 + (_Kx == 0 ? _Sx : _Kx <= _Sx ? _Kx % _Nx + _Myvec[(_Kx - 1) % _Sx] : _Kx % _Nx)) & _Mask);
+                result_type _Rx2 = static_cast<result_type>((_Rx1
+                                                                + (_Kx == 0      ? _Sx
+                                                                    : _Kx <= _Sx ? _Kx % _Nx + _Myvec[(_Kx - 1) % _Sx]
+                                                                                 : _Kx % _Nx))
+                                                            & _Mask);
 
                 _UFirst[(_Kx + _Px) % _Nx] = (_UFirst[(_Kx + _Px) % _Nx] + _Rx1) & _Mask;
                 _UFirst[(_Kx + _Qx) % _Nx] = (_UFirst[(_Kx + _Qx) % _Nx] + _Rx2) & _Mask;
@@ -2929,14 +2932,17 @@ private:
             _Res   = _Xx2;
             _Valid = false;
         } else { // generate two values, store one, return one
+            const _Ty _MinSx{static_cast<_Ty>(7.8159598771420286e-306)};
+            const _Ty _MaxSx{static_cast<_Ty>(1)};
             _Ty _Vx1;
             _Ty _Vx2;
             _Ty _Sx;
             for (;;) { // reject bad values
                 _Vx1 = 2 * _NRAND(_Eng, _Ty) - 1;
                 _Vx2 = 2 * _NRAND(_Eng, _Ty) - 1;
                 _Sx  = _Vx1 * _Vx1 + _Vx2 * _Vx2;
-                if (_Sx < 1 && _Sx != 0) {
+                if (_MinSx < _Sx && _Sx < _MaxSx) {
+                    // Good _Sx value! It will not cause overflow nor generating NaN/Inf on the next calculations.
                     break;
                 }
             }