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msvcrt: Improve strtod precision. 

This fixes strtod precision regression. It also removes floating
point operations.

Signed-off-by: Piotr Caban <piotr@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>
This commit is contained in:
Piotr Caban 2019-12-30 13:23:47 +01:00 committed by Alexandre Julliard
parent 74ec06bee9
commit 5034d109e0
3 changed files with 124 additions and 56 deletions
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1
dlls/msvcrt/msvcrt.h
View File

@ -53,6 +53,7 @@
#define MSVCRT_FLT_MIN_10_EXP (-37)
#define MSVCRT_DBL_MAX_10_EXP 308
#define MSVCRT_DBL_MIN_10_EXP (-307)
#define MSVCRT_DBL_DIG 15
#ifdef _WIN64
#define MSVCRT_SIZE_MAX MSVCRT_UI64_MAX
#else

159
dlls/msvcrt/string.c
View File

@ -343,8 +343,6 @@ void CDECL MSVCRT__swab(char* src, char* dst, int len)
}
}
#if _MSVCR_VER >= 140
enum round {
ROUND_ZERO, /* only used when dropped part contains only zeros */
ROUND_DOWN,
@ -444,6 +442,8 @@ static double make_double(int sign, int exp, ULONGLONG m, enum round round, int
return *((double*)&bits);
}
#if _MSVCR_VER >= 140
static inline int hex2int(char c)
{
if (c >= '0' && c <= '9')
@ -558,26 +558,105 @@ static double strtod16(int sign, const char *p, char **end,
}
#endif
static double MSVCRT_mul_pow10(double x, int exp)
{
BOOL negexp = (exp < 0);
double ret;
struct u128 {
ULONGLONG u[2];
};
if(negexp)
exp = -exp;
ret = pow(10.0, exp);
return (negexp ? x/ret : x*ret);
static inline struct u128 u128_lshift(struct u128 *u)
{
struct u128 r;
r.u[0] = u->u[0] << 1;
r.u[1] = (u->u[1] << 1) + (u->u[0] >> (sizeof(u->u[0])*8-1));
return r;
}
static inline struct u128 u128_rshift(struct u128 *u)
{
struct u128 r;
r.u[0] = (u->u[0] >> 1) + ((u->u[1] & 1) << (sizeof(u->u[1])*8-1));
r.u[1] = u->u[1] >> 1;
return r;
}
static inline void u128_mul10(struct u128 *u)
{
struct u128 tmp;
tmp = u128_lshift(u);
*u = u128_lshift(&tmp);
*u = u128_lshift(u);
u->u[0] += tmp.u[0];
u->u[1] += tmp.u[1];
if (u->u[0] < tmp.u[0]) u->u[1]++;
}
static inline void u128_div10(struct u128 *u)
{
ULONGLONG h, l, r;
r = u->u[1] % 10;
u->u[1] /= 10;
h = (r << 32) + (u->u[0] >> 32);
r = h % 10;
h /= 10;
l = (r << 32) + (u->u[0] & 0xffffffff);
l /= 10;
u->u[0] = (h << 32) + l;
}
static double convert_e10_to_e2(int sign, int e10, ULONGLONG m, int *err)
{
int e2 = 0;
struct u128 u128;
u128.u[0] = m;
u128.u[1] = 0;
while(e10 > 0)
{
u128_mul10(&u128);
e10--;
while(u128.u[1] > MSVCRT_UI64_MAX/16)
{
u128 = u128_rshift(&u128);
e2++;
}
}
while(e10 < 0)
{
while(!(u128.u[1] & (1 << (sizeof(u128.u[1])-1))))
{
u128 = u128_lshift(&u128);
e2--;
}
u128_div10(&u128);
e10++;
}
while(u128.u[1])
{
u128 = u128_rshift(&u128);
e2++;
}
return make_double(sign, e2, u128.u[0], ROUND_DOWN, err);
}
static double strtod_helper(const char *str, char **end, MSVCRT__locale_t locale, int *err)
{
int exp1=0, exp2=0, exp3=0, sign=1;
MSVCRT_pthreadlocinfo locinfo;
unsigned __int64 d=0, hlp;
BOOL found_digit = FALSE;
unsigned fpcontrol;
int exp=0, sign=1;
const char *p;
double ret;
BOOL found_digit = FALSE;
if(err)
*err = 0;
@ -631,13 +710,13 @@ static double strtod_helper(const char *str, char **end, MSVCRT__locale_t locale
found_digit = TRUE;
hlp = d * 10 + *p++ - '0';
if(d>MSVCRT_UI64_MAX/10 || hlp<d) {
exp1++;
exp++;
break;
} else
d = hlp;
}
while(*p>='0' && *p<='9') {
exp1++;
exp++;
p++;
}
@ -650,7 +729,7 @@ static double strtod_helper(const char *str, char **end, MSVCRT__locale_t locale
if(d>MSVCRT_UI64_MAX/10 || hlp<d)
break;
d = hlp;
exp1--;
exp--;
}
while(*p>='0' && *p<='9')
p++;
@ -679,9 +758,9 @@ static double strtod_helper(const char *str, char **end, MSVCRT__locale_t locale
}
e *= s;
if(exp1<0 && e<0 && exp1+e>=0) exp1 = INT_MIN;
else if(exp1>0 && e>0 && exp1+e<0) exp1 = INT_MAX;
else exp3 = e;
if(exp<0 && e<0 && exp+e>=0) exp = INT_MIN;
else if(exp>0 && e>0 && exp+e<0) exp = INT_MAX;
else exp += e;
} else {
if(*p=='-' || *p=='+')
p--;
@ -689,39 +768,19 @@ static double strtod_helper(const char *str, char **end, MSVCRT__locale_t locale
}
}
fpcontrol = _control87(0, 0);
_control87(MSVCRT__EM_DENORMAL|MSVCRT__EM_INVALID|MSVCRT__EM_ZERODIVIDE
|MSVCRT__EM_OVERFLOW|MSVCRT__EM_UNDERFLOW|MSVCRT__EM_INEXACT|MSVCRT__PC_64,
MSVCRT__MCW_EM | MSVCRT__MCW_PC );
/* take the number without exponent and convert it into a double */
ret = MSVCRT_mul_pow10(d, exp1);
/* shift the number to the representation where the first non-zero digit is in the ones place */
exp2 = (ret != 0.0 ? (int)round(log10(ret)) : 0);
if (exp3-exp2 >= MSVCRT_FLT_MIN_10_EXP && exp3-exp2 <= MSVCRT_FLT_MAX_10_EXP)
exp2 = 0; /* only bother to take this extra step with very small or very large numbers */
/* incorporate an additional shift to deal with floating point denormal values (if necessary) */
if(exp3-exp2 < MSVCRT_DBL_MIN_10_EXP)
exp2 += exp3-exp2-MSVCRT_DBL_MIN_10_EXP;
ret = MSVCRT_mul_pow10(ret, exp2);
/* apply the exponent (and undo any shift) */
ret = MSVCRT_mul_pow10(ret, exp3-exp2);
/* apply the sign bit */
ret *= sign;
_control87( fpcontrol, MSVCRT__MCW_EM | MSVCRT__MCW_PC );
if((d && ret==0.0) || isinf(ret)) {
if(err)
*err = MSVCRT_ERANGE;
else
*MSVCRT__errno() = MSVCRT_ERANGE;
}
if(end)
*end = (char*)p;
return ret;
if(!err) err = MSVCRT__errno();
if(!d) return make_double(sign, exp, d, ROUND_ZERO, err);
if(exp > MSVCRT_DBL_MAX_10_EXP)
return make_double(sign, INT_MAX, d, ROUND_ZERO, err);
/* Count part of exponent stored in denormalized mantissa. */
/* Increase exponent range to handle subnormals. */
if(exp < MSVCRT_DBL_MIN_10_EXP-MSVCRT_DBL_DIG-18)
return make_double(sign, INT_MIN, d, ROUND_ZERO, err);
return convert_e10_to_e2(sign, exp, d, err);
}
/*********************************************************************

20
dlls/ucrtbase/tests/string.c
View File

@ -118,16 +118,19 @@ static BOOL local_isnan(double d)
return d != d;
}
#define test_strtod_str(string, value, length) _test_strtod_str(__LINE__, string, value, length)
static void _test_strtod_str(int line, const char* string, double value, int length)
#define test_strtod_str(string, value, length) _test_strtod_str(__LINE__, string, value, length, FALSE)
#define test_strtod_str_todo(string, value, length) _test_strtod_str(__LINE__, string, value, length, TRUE)
static void _test_strtod_str(int line, const char* string, double value, int length, BOOL todo)
{
char *end;
double d;
d = p_strtod(string, &end);
if (local_isnan(value))
ok_(__FILE__, line)(local_isnan(d), "d = %.16le (\"%s\")\n", d, string);
else
ok_(__FILE__, line)(d == value, "d = %.16le (\"%s\")\n", d, string);
todo_wine_if(todo) {
if (local_isnan(value))
ok_(__FILE__, line)(local_isnan(d), "d = %.16le (\"%s\")\n", d, string);
else
ok_(__FILE__, line)(d == value, "d = %.16le (\"%s\")\n", d, string);
}
ok_(__FILE__, line)(end == string + length, "incorrect end (%d, \"%s\")\n", (int)(end - string), string);
}
@ -173,6 +176,11 @@ static void test_strtod(void)
test_strtod_str("0x1ffffffffffffe.80000000000000000001", 9007199254740991.0, 37);
test_strtod_str("0x1fffffffffffff.80000000000000000000", 9007199254740992.0, 37);
test_strtod_str("0x1fffffffffffff.80000000000000000001", 9007199254740992.0, 37);
test_strtod_str("4.0621786324484881721115322e-53", 4.0621786324484881721115322e-53, 31);
test_strtod_str_todo("1.8905590910042396899370942", 1.8905590910042396899370942, 27);
test_strtod_str("2.2250738585072014e-308", 2.2250738585072014e-308, 23);
test_strtod_str("4.9406564584124654e-324", 4.9406564584124654e-324, 23);
}
static void test__memicmp(void)