Erich E. Hoover : msvcrt: Implement strtod without using 'long double'.
Alexandre Julliard
julliard at winehq.org
Thu Dec 19 16:00:05 CST 2019
Module: wine
Branch: master
Commit: c22af971c287933a137c9fbecc81823812e12b7a
URL: https://source.winehq.org/git/wine.git/?a=commit;h=c22af971c287933a137c9fbecc81823812e12b7a
Author: Erich E. Hoover <erich.e.hoover at gmail.com>
Date: Wed Dec 18 15:48:11 2019 -0700
msvcrt: Implement strtod without using 'long double'.
Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=48160
Signed-off-by: Erich E. Hoover <erich.e.hoover at gmail.com>
Signed-off-by: Alexandre Julliard <julliard at winehq.org>
---
dlls/msvcrt/msvcrt.h | 2 ++
dlls/msvcrt/string.c | 67 ++++++++++++++++++++++++++++++----------------
dlls/msvcrt/tests/string.c | 46 ++++++++++++++++++++++++++++---
3 files changed, 89 insertions(+), 26 deletions(-)
diff --git a/dlls/msvcrt/msvcrt.h b/dlls/msvcrt/msvcrt.h
index 3933c0fa3e..2ac7977182 100644
--- a/dlls/msvcrt/msvcrt.h
+++ b/dlls/msvcrt/msvcrt.h
@@ -49,6 +49,8 @@
#define MSVCRT_I64_MIN (-MSVCRT_I64_MAX-1)
#define MSVCRT_UI64_MAX (((unsigned __int64)0xffffffff << 32) | 0xffffffff)
#define MSVCRT_MB_LEN_MAX 5
+#define MSVCRT_DBL_MAX_10_EXP 308
+#define MSVCRT_DBL_MIN_10_EXP (-307)
#ifdef _WIN64
#define MSVCRT_SIZE_MAX MSVCRT_UI64_MAX
#else
diff --git a/dlls/msvcrt/string.c b/dlls/msvcrt/string.c
index b78d93a917..03d80a5dec 100644
--- a/dlls/msvcrt/string.c
+++ b/dlls/msvcrt/string.c
@@ -558,16 +558,26 @@ 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;
+
+ if(negexp)
+ exp = -exp;
+ ret = pow(10.0, exp);
+ return (negexp ? x/ret : x*ret);
+}
+
static double strtod_helper(const char *str, char **end, MSVCRT__locale_t locale, int *err)
{
+ BOOL found_digit = FALSE, overflow, underflow;
+ int exp1=0, exp2=0, exp3=0, sign=1;
MSVCRT_pthreadlocinfo locinfo;
unsigned __int64 d=0, hlp;
unsigned fpcontrol;
- int exp=0, sign=1;
const char *p;
double ret;
- long double lret=1, expcnt = 10;
- BOOL found_digit = FALSE, negexp;
if(err)
*err = 0;
@@ -621,13 +631,13 @@ 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) {
- exp++;
+ exp1++;
break;
} else
d = hlp;
}
while(*p>='0' && *p<='9') {
- exp++;
+ exp1++;
p++;
}
@@ -640,7 +650,7 @@ static double strtod_helper(const char *str, char **end, MSVCRT__locale_t locale
if(d>MSVCRT_UI64_MAX/10 || hlp<d)
break;
d = hlp;
- exp--;
+ exp1--;
}
while(*p>='0' && *p<='9')
p++;
@@ -669,9 +679,9 @@ static double strtod_helper(const char *str, char **end, MSVCRT__locale_t locale
}
e *= s;
- 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;
+ 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;
} else {
if(*p=='-' || *p=='+')
p--;
@@ -681,20 +691,31 @@ 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, 0xffffffff);
-
- 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);
+ |MSVCRT__EM_OVERFLOW|MSVCRT__EM_UNDERFLOW|MSVCRT__EM_INEXACT|MSVCRT__PC_64,
+ MSVCRT__MCW_EM | MSVCRT__MCW_PC );
+
+ /* if we have a simple case then just calculate the result directly */
+ overflow = (exp3-exp1 > MSVCRT_DBL_MAX_10_EXP);
+ underflow = (exp3-exp1 < MSVCRT_DBL_MIN_10_EXP);
+ if(!overflow && !underflow) {
+ exp1 += exp3;
+ exp3 = 0;
+ }
+ /* 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 */
+ if(overflow || underflow)
+ exp2 = (ret != 0.0 ? (int)log10(ret) : 0);
+ /* 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)
diff --git a/dlls/msvcrt/tests/string.c b/dlls/msvcrt/tests/string.c
index f814a22bdb..beca47f1b6 100644
--- a/dlls/msvcrt/tests/string.c
+++ b/dlls/msvcrt/tests/string.c
@@ -28,6 +28,7 @@
#include <locale.h>
#include <errno.h>
#include <limits.h>
+#include <float.h>
#include <math.h>
/* make it use a definition from string.h */
@@ -1885,6 +1886,13 @@ static inline BOOL almost_equal(double d1, double d2) {
return FALSE;
}
+static inline BOOL large_almost_equal(double d1, double d2) {
+ double diff = fabs(d1-d2);
+ if(diff / (fabs(d1) + fabs(d2)) < DBL_EPSILON)
+ return TRUE;
+ return FALSE;
+}
+
static void test__strtod(void)
{
const char double1[] = "12.1";
@@ -1990,6 +1998,9 @@ static void test__strtod(void)
errno = 0xdeadbeef;
strtod("-1d309", NULL);
ok(errno == ERANGE, "errno = %x\n", errno);
+
+ d = strtod("1.7976931348623158e+308", NULL);
+ ok(almost_equal(d, DBL_MAX), "d = %lf (%lf)\n", d, DBL_MAX);
}
static void test_mbstowcs(void)
@@ -2984,11 +2995,28 @@ static void test_tolower(void)
setlocale(LC_ALL, "C");
}
+static double mul_pow10(double x, double exp)
+{
+ int fpexcept = _EM_DENORMAL|_EM_INVALID|_EM_ZERODIVIDE|_EM_OVERFLOW|_EM_UNDERFLOW|_EM_INEXACT;
+ BOOL negexp = (exp < 0);
+ int fpcontrol;
+ double ret;
+
+ if(negexp)
+ exp = -exp;
+ fpcontrol = _control87(0, 0);
+ _control87(fpexcept, 0xffffffff);
+ ret = pow(10.0, exp);
+ ret = (negexp ? x/ret : x*ret);
+ _control87(fpcontrol, 0xffffffff);
+ return ret;
+}
+
static void test__atodbl(void)
{
_CRT_DOUBLE d;
char num[32];
- int ret;
+ int i, j, ret;
if(!p__atodbl_l) {
/* Old versions of msvcrt use different values for _OVERFLOW and _UNDERFLOW
@@ -3029,13 +3057,25 @@ static void test__atodbl(void)
ok(ret == 0, "_atodbl(&d, \"123\") returned %d, expected 0\n", ret);
ok(d.x == 123, "d.x = %lf, expected 123\n", d.x);
+ /* check over the whole range of (simple) normal doubles */
+ for (j = DBL_MIN_10_EXP; j <= DBL_MAX_10_EXP; j++) {
+ for (i = 1; i <= 9; i++) {
+ double expected = mul_pow10(i, j);
+ if (expected < DBL_MIN || expected > DBL_MAX) continue;
+ snprintf(num, sizeof(num), "%de%d", i, j);
+ ret = _atodbl(&d, num);
+ ok(large_almost_equal(d.x, expected), "d.x = %le, expected %le\n", d.x, expected);
+ }
+ }
+
+ /* check with denormal doubles */
strcpy(num, "1e-309");
ret = p__atodbl_l(&d, num, NULL);
ok(ret == _UNDERFLOW, "_atodbl_l(&d, \"1e-309\", NULL) returned %d, expected _UNDERFLOW\n", ret);
- ok(d.x!=0 && almost_equal(d.x, 0), "d.x = %le, expected 0\n", d.x);
+ ok(d.x!=0 && almost_equal(d.x, 0.1e-308), "d.x = %le, expected 0.1e-308\n", d.x);
ret = _atodbl(&d, num);
ok(ret == _UNDERFLOW, "_atodbl(&d, \"1e-309\") returned %d, expected _UNDERFLOW\n", ret);
- ok(d.x!=0 && almost_equal(d.x, 0), "d.x = %le, expected 0\n", d.x);
+ ok(d.x!=0 && almost_equal(d.x, 0.1e-308), "d.x = %le, expected 0.1e-308\n", d.x);
strcpy(num, "1e309");
ret = p__atodbl_l(&d, num, NULL);
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