Piotr Caban : msvcrt: Improved _wcstod_l precision.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 505e5a162fb94e5a3789191121e5b5fd32687d11
URL:    http://source.winehq.org/git/wine.git/?a=commit;h=505e5a162fb94e5a3789191121e5b5fd32687d11

Author: Piotr Caban <piotr at codeweavers.com>
Date:   Tue Nov  6 10:33:40 2012 +0100

msvcrt: Improved _wcstod_l precision.

---

 dlls/msvcrt/wcs.c |   17 ++++++++++++-----
 1 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/dlls/msvcrt/wcs.c b/dlls/msvcrt/wcs.c
index 32ee76b..08628d4 100644
--- a/dlls/msvcrt/wcs.c
+++ b/dlls/msvcrt/wcs.c
@@ -202,7 +202,8 @@ double CDECL MSVCRT__wcstod_l(const MSVCRT_wchar_t* str, MSVCRT_wchar_t** end,
     int exp=0, sign=1;
     const MSVCRT_wchar_t *p;
     double ret;
-    BOOL found_digit = FALSE;
+    long double lret=1, expcnt = 10;
+    BOOL found_digit = FALSE, negexp;
 
     if (!MSVCRT_CHECK_PMT(str != NULL)) return 0;
 
@@ -287,10 +288,16 @@ double CDECL MSVCRT__wcstod_l(const MSVCRT_wchar_t* str, MSVCRT_wchar_t** end,
     _control87(MSVCRT__EM_DENORMAL|MSVCRT__EM_INVALID|MSVCRT__EM_ZERODIVIDE
             |MSVCRT__EM_OVERFLOW|MSVCRT__EM_UNDERFLOW|MSVCRT__EM_INEXACT, 0xffffffff);
 
-    if(exp>0)
-        ret = (double)sign*d*pow(10, exp);
-    else
-        ret = (double)sign*d/pow(10, -exp);
+    negexp = (exp < 0);
+    if(negexp)
+        exp = -exp;
+    while(exp) {
+        if(exp & 1)
+            lret *= expcnt;
+        exp /= 2;
+        expcnt = expcnt*expcnt;
+    }
+    ret = (long double)sign * (negexp ? d/lret : d*lret);
 
     _control87(fpcontrol, 0xffffffff);