msvcrt: Improved _atoflt_l precision.

dlls/msvcrt/msvcrt.h

@@ -983,6 +983,7 @@ int pf_printf_w(puts_clbk_w, void*, const MSVCRT_wchar_t*, MSVCRT__locale_t,
         BOOL, BOOL, args_clbk, void*, __ms_va_list*) DECLSPEC_HIDDEN;
 printf_arg arg_clbk_valist(void*, int, int, __ms_va_list*) DECLSPEC_HIDDEN;
 
+#define MSVCRT_FLT_MIN 1.175494351e-38F
 #define MSVCRT__OVERFLOW  3
 #define MSVCRT__UNDERFLOW 4
 

dlls/msvcrt/string.c

@@ -514,13 +514,13 @@ int CDECL MSVCRT__atoflt_l( MSVCRT__CRT_FLOAT *value, char *str, MSVCRT__locale_
             |MSVCRT__EM_OVERFLOW|MSVCRT__EM_UNDERFLOW|MSVCRT__EM_INEXACT, 0xffffffff);
 
     if(exp>0)
-        value->f = (float)sign*d*powf(10, exp);
+        value->f = (double)sign*d*pow(10, exp);
     else
-        value->f = (float)sign*d/powf(10, -exp);
+        value->f = (double)sign*d/pow(10, -exp);
 
     _control87(fpcontrol, 0xffffffff);
 
-    if((d && value->f==0.0) || isinf(value->f))
+    if((d && value->f>-MSVCRT_FLT_MIN && value->f<MSVCRT_FLT_MIN) || isinf(value->f))
         ret = exp > 0 ? MSVCRT__OVERFLOW : MSVCRT__UNDERFLOW;
 
     return ret;