Piotr Caban : msvcrt: Fix rounding of numbers smaller than minimal subnormal.
Alexandre Julliard
julliard at winehq.org
Thu Jul 23 16:36:57 CDT 2020
Module: wine
Branch: master
Commit: 29288c0bc0ea724bf27ffa1e731e4d4b5b45643b
URL: https://source.winehq.org/git/wine.git/?a=commit;h=29288c0bc0ea724bf27ffa1e731e4d4b5b45643b
Author: Piotr Caban <piotr at codeweavers.com>
Date: Thu Jul 23 15:38:46 2020 +0200
msvcrt: Fix rounding of numbers smaller than minimal subnormal.
Signed-off-by: Piotr Caban <piotr at codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard at winehq.org>
---
dlls/msvcrt/string.c | 28 +++++++++++++++-------------
dlls/ucrtbase/tests/string.c | 2 ++
2 files changed, 17 insertions(+), 13 deletions(-)
diff --git a/dlls/msvcrt/string.c b/dlls/msvcrt/string.c
index 5b6d73626a..ab6747db5c 100644
--- a/dlls/msvcrt/string.c
+++ b/dlls/msvcrt/string.c
@@ -413,25 +413,21 @@ int fpnum_double(struct fpnum *fp, double *d)
fp->m >>= 1;
fp->exp++;
}
-
- /* handle subnormal that falls into regular range due to rounding */
fp->exp += (1 << (EXP_BITS-1)) - 1;
- if (!fp->exp && (fp->mod == FP_ROUND_UP || (fp->mod == FP_ROUND_EVEN && fp->m & 1)))
- {
- if (fp->m + 1 >= (ULONGLONG)1 << MANT_BITS)
- {
- fp->m++;
- fp->m >>= 1;
- fp->exp++;
- fp->mod = FP_ROUND_DOWN;
- }
- }
/* handle subnormals */
if (fp->exp <= 0)
+ {
+ if (fp->m & 1 && fp->mod == FP_ROUND_ZERO) fp->mod = FP_ROUND_EVEN;
+ else if (fp->m & 1) fp->mod = FP_ROUND_UP;
+ else if (fp->mod != FP_ROUND_ZERO) fp->mod = FP_ROUND_DOWN;
fp->m >>= 1;
+ }
while(fp->m && fp->exp<0)
{
+ if (fp->m & 1 && fp->mod == FP_ROUND_ZERO) fp->mod = FP_ROUND_EVEN;
+ else if (fp->m & 1) fp->mod = FP_ROUND_UP;
+ else if (fp->mod != FP_ROUND_ZERO) fp->mod = FP_ROUND_DOWN;
fp->m >>= 1;
fp->exp++;
}
@@ -440,7 +436,13 @@ int fpnum_double(struct fpnum *fp, double *d)
if (fp->mod == FP_ROUND_UP || (fp->mod == FP_ROUND_EVEN && fp->m & 1))
{
fp->m++;
- if (fp->m >= (ULONGLONG)1 << MANT_BITS)
+
+ /* handle subnormal that falls into regular range due to rounding */
+ if (fp->m == (ULONGLONG)1 << (MANT_BITS - 1))
+ {
+ fp->exp++;
+ }
+ else if (fp->m >= (ULONGLONG)1 << MANT_BITS)
{
fp->exp++;
fp->m >>= 1;
diff --git a/dlls/ucrtbase/tests/string.c b/dlls/ucrtbase/tests/string.c
index 5857a02773..3a4b8b9f04 100644
--- a/dlls/ucrtbase/tests/string.c
+++ b/dlls/ucrtbase/tests/string.c
@@ -148,6 +148,8 @@ static void test_strtod(void)
test_strtod_str("1.7976931348623158e+308", 1.7976931348623158e+308, 23);
test_strtod_str("2.2250738585072014e-308", 2.2250738585072014e-308, 23);
test_strtod_str("4.9406564584124654e-324", 4.9406564584124654e-324, 23);
+ test_strtod_str("2.48e-324", 4.9406564584124654e-324, 9);
+ test_strtod_str_errno("2.47e-324", 0, 9, ERANGE);
}
static void test__memicmp(void)
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