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ntdll: Copy sqrt() implementation from msvcrt.

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Signed-off-by: Alexandre Julliard <julliard@winehq.org>
This commit is contained in:
Alexandre Julliard 2021-10-26 10:34:06 +02:00
parent 140cd3553c
commit 2e4c090c5e
1 changed files with 132 additions and 2 deletions
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134
dlls/ntdll/math.c
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@ -1047,6 +1047,37 @@ static inline int pow_checkint(UINT64 iy)
return 2;
}
/* Copied from musl: src/math/__fpclassify.c */
static short _dclass(double x)
{
union { double f; UINT64 i; } u = { x };
int e = u.i >> 52 & 0x7ff;
if (!e) return u.i << 1 ? FP_SUBNORMAL : FP_ZERO;
if (e == 0x7ff) return (u.i << 12) ? FP_NAN : FP_INFINITE;
return FP_NORMAL;
}
static BOOL sqrt_validate( double *x, BOOL update_sw )
{
short c = _dclass(*x);
if (c == FP_ZERO) return FALSE;
if (c == FP_NAN)
{
/* set signaling bit */
*(ULONGLONG*)x |= 0x8000000000000ULL;
return FALSE;
}
if (signbit(*x))
{
*x = -NAN;
return FALSE;
}
if (c == FP_INFINITE) return FALSE;
return TRUE;
}
/*********************************************************************
* abs (NTDLL.@)
@ -1756,10 +1787,109 @@ double CDECL sin( double x )
/*********************************************************************
* sqrt (NTDLL.@)
*
* Copied from musl: src/math/sqrt.c
*/
double CDECL sqrt( double d )
double CDECL sqrt( double x )
{
return unix_funcs->sqrt( d );
static const double tiny = 1.0e-300;
double z;
int sign = 0x80000000;
int ix0,s0,q,m,t,i;
unsigned int r,t1,s1,ix1,q1;
ULONGLONG ix;
if (!sqrt_validate(&x, TRUE))
return x;
ix = *(ULONGLONG*)&x;
ix0 = ix >> 32;
ix1 = ix;
/* normalize x */
m = ix0 >> 20;
if (m == 0) { /* subnormal x */
while (ix0 == 0) {
m -= 21;
ix0 |= (ix1 >> 11);
ix1 <<= 21;
}
for (i=0; (ix0 & 0x00100000) == 0; i++)
ix0 <<= 1;
m -= i - 1;
ix0 |= ix1 >> (32 - i);
ix1 <<= i;
}
m -= 1023; /* unbias exponent */
ix0 = (ix0 & 0x000fffff) | 0x00100000;
if (m & 1) { /* odd m, double x to make it even */
ix0 += ix0 + ((ix1 & sign) >> 31);
ix1 += ix1;
}
m >>= 1; /* m = [m/2] */
/* generate sqrt(x) bit by bit */
ix0 += ix0 + ((ix1 & sign) >> 31);
ix1 += ix1;
q = q1 = s0 = s1 = 0; /* [q,q1] = sqrt(x) */
r = 0x00200000; /* r = moving bit from right to left */
while (r != 0) {
t = s0 + r;
if (t <= ix0) {
s0 = t + r;
ix0 -= t;
q += r;
}
ix0 += ix0 + ((ix1 & sign) >> 31);
ix1 += ix1;
r >>= 1;
}
r = sign;
while (r != 0) {
t1 = s1 + r;
t = s0;
if (t < ix0 || (t == ix0 && t1 <= ix1)) {
s1 = t1 + r;
if ((t1&sign) == sign && (s1 & sign) == 0)
s0++;
ix0 -= t;
if (ix1 < t1)
ix0--;
ix1 -= t1;
q1 += r;
}
ix0 += ix0 + ((ix1 & sign) >> 31);
ix1 += ix1;
r >>= 1;
}
/* use floating add to find out rounding direction */
if ((ix0 | ix1) != 0) {
z = 1.0 - tiny; /* raise inexact flag */
if (z >= 1.0) {
z = 1.0 + tiny;
if (q1 == (unsigned int)0xffffffff) {
q1 = 0;
q++;
} else if (z > 1.0) {
if (q1 == (unsigned int)0xfffffffe)
q++;
q1 += 2;
} else
q1 += q1 & 1;
}
}
ix0 = (q >> 1) + 0x3fe00000;
ix1 = q1 >> 1;
if (q & 1)
ix1 |= sign;
ix = ix0 + ((unsigned int)m << 20);
ix <<= 32;
ix |= ix1;
return *(double*)&ix;
}
/*********************************************************************