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PowerPC floating point little-endian [4 of 15]

http://sourceware.org/ml/libc-alpha/2013-08/msg00084.html

Another batch of ieee854 macros and union replacement.  These four
files also have bugs fixed with this patch.  The fact that the two
doubles in an IBM long double may have different signs means that
negation and absolute value operations can't just twiddle one sign bit
as you can with ieee864 style extended double.  fmodl, remainderl,
erfl and erfcl all had errors of this type.  erfl also returned +1 for
large magnitude negative input where it should return -1.  The hypotl
error is innocuous since the value adjusted twice is only used as a
flag.  The e_hypotl.c tests for large "a" and small "b" are mutually
exclusive because we've already exited when x/y > 2**120.  That allows
some further small simplifications.

	[BZ #15734], [BZ #15735]
	* sysdeps/ieee754/ldbl-128ibm/e_fmodl.c (__ieee754_fmodl): Rewrite
	all uses of ieee875 long double macros and unions.  Simplify test
	for 0.0L.  Correct |x|<|y| and |x|=|y| test.  Use
	ldbl_extract_mantissa value for ix,iy exponents.  Properly
	normalize after ldbl_extract_mantissa, and don't add hidden bit
	already handled.  Don't treat low word of ieee854 mantissa like
	low word of IBM long double and mask off bit when testing for
	zero.
	* sysdeps/ieee754/ldbl-128ibm/e_hypotl.c (__ieee754_hypotl): Rewrite
	all uses of ieee875 long double macros and unions.  Simplify tests
	for 0.0L and inf.  Correct double adjustment of k.  Delete dead code
	adjusting ha,hb.  Simplify code setting kld.  Delete two600 and
	two1022, instead use their values.  Recognise that tests for large
	"a" and small "b" are mutually exclusive.  Rename vars.  Comment.
	* sysdeps/ieee754/ldbl-128ibm/e_remainderl.c (__ieee754_remainderl):
	Rewrite all uses of ieee875 long double macros and unions.  Simplify
	test for 0.0L and nan.  Correct negation.
	* sysdeps/ieee754/ldbl-128ibm/s_erfl.c (__erfl): Rewrite all uses of
	ieee875 long double macros and unions.  Correct output for large
	magnitude x.  Correct absolute value calculation.
	(__erfcl): Likewise.
	* math/libm-test.inc: Add tests for errors discovered in IBM long
	double versions of fmodl, remainderl, erfl and erfcl.
This commit is contained in:
Alan Modra 2013-08-17 18:25:51 +09:30
parent 765714cafc
commit 650ef4bd79
6 changed files with 198 additions and 134 deletions

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@ -1,3 +1,30 @@
2013-10-04 Alan Modra <amodra@gmail.com>
[BZ #15734], [BZ #15735]
* sysdeps/ieee754/ldbl-128ibm/e_fmodl.c (__ieee754_fmodl): Rewrite
all uses of ieee875 long double macros and unions. Simplify test
for 0.0L. Correct |x|<|y| and |x|=|y| test. Use
ldbl_extract_mantissa value for ix,iy exponents. Properly
normalize after ldbl_extract_mantissa, and don't add hidden bit
already handled. Don't treat low word of ieee854 mantissa like
low word of IBM long double and mask off bit when testing for
zero.
* sysdeps/ieee754/ldbl-128ibm/e_hypotl.c (__ieee754_hypotl): Rewrite
all uses of ieee875 long double macros and unions. Simplify tests
for 0.0L and inf. Correct double adjustment of k. Delete dead code
adjusting ha,hb. Simplify code setting kld. Delete two600 and
two1022, instead use their values. Recognise that tests for large
"a" and small "b" are mutually exclusive. Rename vars. Comment.
* sysdeps/ieee754/ldbl-128ibm/e_remainderl.c (__ieee754_remainderl):
Rewrite all uses of ieee875 long double macros and unions. Simplify
test for 0.0L and nan. Correct negation.
* sysdeps/ieee754/ldbl-128ibm/s_erfl.c (__erfl): Rewrite all uses of
ieee875 long double macros and unions. Correct output for large
magnitude x. Correct absolute value calculation.
(__erfcl): Likewise.
* math/libm-test.inc: Add tests for errors discovered in IBM long
double versions of fmodl, remainderl, erfl and erfcl.
2013-10-04 Alan Modra <amodra@gmail.com>
* sysdeps/ieee754/ldbl-128ibm/e_atan2l.c (__ieee754_atan2l): Rewrite

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@ -7829,6 +7829,11 @@ static const struct test_f_f_data erf_test_data[] =
TEST_f_f (erf, 2.0L, 0.995322265018952734162069256367252929L),
TEST_f_f (erf, 4.125L, 0.999999994576599200434933994687765914L),
TEST_f_f (erf, 27.0L, 1.0L),
TEST_f_f (erf, -27.0L, -1.0L),
#if defined TEST_LDOUBLE && LDBL_MANT_DIG >= 54
/* The input is not exactly representable as a double. */
TEST_f_f (erf, -0x1.fffffffffffff8p-2L, -0.5204998778130465132916303345518417673509L),
#endif
};
static void
@ -7857,6 +7862,10 @@ static const struct test_f_f_data erfc_test_data[] =
TEST_f_f (erfc, 0x1.ffa002p+2L, 1.233585992097580296336099501489175967033e-29L),
TEST_f_f (erfc, 0x1.ffffc8p+2L, 1.122671365033056305522366683719541099329e-29L),
#ifdef TEST_LDOUBLE
# if LDBL_MANT_DIG >= 54
/* The input is not exactly representable as a double. */
TEST_f_f (erfc, -0x1.fffffffffffff8p-2L, 1.52049987781304651329163033455184176735L),
# endif
/* The result can only be represented in long double. */
# if LDBL_MIN_10_EXP < -319
TEST_f_f (erfc, 27.0L, 0.523704892378925568501606768284954709e-318L),
@ -9354,6 +9363,13 @@ static const struct test_ff_f_data fmod_test_data[] =
#endif
#if defined TEST_LDOUBLE && LDBL_MIN_EXP <= -16381
TEST_ff_f (fmod, 0x0.fffffffffffffffep-16382L, 0x1p-16445L, plus_zero, NO_INEXACT_EXCEPTION),
#endif
#if defined TEST_LDOUBLE && LDBL_MANT_DIG >= 56
TEST_ff_f (fmod, -0x1.00000000000004p+0L, 0x1.fffffffffffff8p-1L, -0x1p-53L, NO_INEXACT_EXCEPTION),
TEST_ff_f (fmod, 0x1.fffffffffffffap-1L, 0x1.fffffffffffff8p-1L, 0x1p-56L, NO_INEXACT_EXCEPTION),
TEST_ff_f (fmod, -0x1.fffffffffffffap-1L, 0x1.fffffffffffff8p-1L, -0x1p-56L, NO_INEXACT_EXCEPTION),
TEST_ff_f (fmod, 0x1.fffffffffffffap-1L, -0x1.fffffffffffff8p-1L, 0x1p-56L, NO_INEXACT_EXCEPTION),
TEST_ff_f (fmod, -0x1.fffffffffffffap-1L, -0x1.fffffffffffff8p-1L, -0x1p-56L, NO_INEXACT_EXCEPTION),
#endif
};
@ -12316,6 +12332,9 @@ static const struct test_ff_f_data remainder_test_data[] =
TEST_ff_f (remainder, -1.625, -1.0, 0.375, NO_INEXACT_EXCEPTION),
TEST_ff_f (remainder, 5.0, 2.0, 1.0, NO_INEXACT_EXCEPTION),
TEST_ff_f (remainder, 3.0, 2.0, -1.0, NO_INEXACT_EXCEPTION),
#if defined TEST_LDOUBLE && LDBL_MANT_DIG >= 56
TEST_ff_f (remainder, -0x1.80000000000002p1L, 2.0, 0x1.fffffffffffff8p-1L, NO_INEXACT_EXCEPTION),
#endif
};
static void

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@ -27,76 +27,83 @@ static const long double one = 1.0, Zero[] = {0.0, -0.0,};
long double
__ieee754_fmodl (long double x, long double y)
{
int64_t n,hx,hy,hz,ix,iy,sx, i;
u_int64_t lx,ly,lz;
int temp;
int64_t hx, hy, hz, sx, sy;
uint64_t lx, ly, lz;
int n, ix, iy;
double xhi, xlo, yhi, ylo;
GET_LDOUBLE_WORDS64(hx,lx,x);
GET_LDOUBLE_WORDS64(hy,ly,y);
ldbl_unpack (x, &xhi, &xlo);
EXTRACT_WORDS64 (hx, xhi);
EXTRACT_WORDS64 (lx, xlo);
ldbl_unpack (y, &yhi, &ylo);
EXTRACT_WORDS64 (hy, yhi);
EXTRACT_WORDS64 (ly, ylo);
sx = hx&0x8000000000000000ULL; /* sign of x */
hx ^=sx; /* |x| */
hy &= 0x7fffffffffffffffLL; /* |y| */
hx ^= sx; /* |x| */
sy = hy&0x8000000000000000ULL; /* sign of y */
hy ^= sy; /* |y| */
/* purge off exception values */
if(__builtin_expect((hy|(ly&0x7fffffffffffffff))==0 ||
if(__builtin_expect(hy==0 ||
(hx>=0x7ff0000000000000LL)|| /* y=0,or x not finite */
(hy>0x7ff0000000000000LL),0)) /* or y is NaN */
return (x*y)/(x*y);
if(__builtin_expect(hx<=hy,0)) {
if((hx<hy)||(lx<ly)) return x; /* |x|<|y| return x */
if(lx==ly)
return Zero[(u_int64_t)sx>>63]; /* |x|=|y| return x*0*/
if (__builtin_expect (hx <= hy, 0))
{
/* If |x| < |y| return x. */
if (hx < hy)
return x;
/* At this point the absolute value of the high doubles of
x and y must be equal. */
/* If the low double of y is the same sign as the high
double of y (ie. the low double increases |y|)... */
if (((ly ^ sy) & 0x8000000000000000LL) == 0
/* ... then a different sign low double to high double
for x or same sign but lower magnitude... */
&& (int64_t) (lx ^ sx) < (int64_t) (ly ^ sy))
/* ... means |x| < |y|. */
return x;
/* If the low double of x differs in sign to the high
double of x (ie. the low double decreases |x|)... */
if (((lx ^ sx) & 0x8000000000000000LL) != 0
/* ... then a different sign low double to high double
for y with lower magnitude (we've already caught
the same sign for y case above)... */
&& (int64_t) (lx ^ sx) > (int64_t) (ly ^ sy))
/* ... means |x| < |y|. */
return x;
/* If |x| == |y| return x*0. */
if ((lx ^ sx) == (ly ^ sy))
return Zero[(uint64_t) sx >> 63];
}
/* determine ix = ilogb(x) */
if(__builtin_expect(hx<0x0010000000000000LL,0)) { /* subnormal x */
if(hx==0) {
for (ix = -1043, i=lx; i>0; i<<=1) ix -=1;
} else {
for (ix = -1022, i=(hx<<11); i>0; i<<=1) ix -=1;
}
} else ix = (hx>>52)-0x3ff;
/* determine iy = ilogb(y) */
if(__builtin_expect(hy<0x0010000000000000LL,0)) { /* subnormal y */
if(hy==0) {
for (iy = -1043, i=ly; i>0; i<<=1) iy -=1;
} else {
for (iy = -1022, i=(hy<<11); i>0; i<<=1) iy -=1;
}
} else iy = (hy>>52)-0x3ff;
/* Make the IBM extended format 105 bit mantissa look like the ieee854 112
bit mantissa so the following operations will give the correct
result. */
ldbl_extract_mantissa(&hx, &lx, &temp, x);
ldbl_extract_mantissa(&hy, &ly, &temp, y);
ldbl_extract_mantissa(&hx, &lx, &ix, x);
ldbl_extract_mantissa(&hy, &ly, &iy, y);
/* set up {hx,lx}, {hy,ly} and align y to x */
if(__builtin_expect(ix >= -1022, 1))
hx = 0x0001000000000000LL|(0x0000ffffffffffffLL&hx);
else { /* subnormal x, shift x to normal */
n = -1022-ix;
if(n<=63) {
hx = (hx<<n)|(lx>>(64-n));
lx <<= n;
} else {
hx = lx<<(n-64);
lx = 0;
}
}
if(__builtin_expect(iy >= -1022, 1))
hy = 0x0001000000000000LL|(0x0000ffffffffffffLL&hy);
else { /* subnormal y, shift y to normal */
n = -1022-iy;
if(n<=63) {
hy = (hy<<n)|(ly>>(64-n));
ly <<= n;
} else {
hy = ly<<(n-64);
ly = 0;
}
}
if (__builtin_expect (ix == -IEEE754_DOUBLE_BIAS, 0))
{
/* subnormal x, shift x to normal. */
while ((hx & (1LL << 48)) == 0)
{
hx = (hx << 1) | (lx >> 63);
lx = lx << 1;
ix -= 1;
}
}
if (__builtin_expect (iy == -IEEE754_DOUBLE_BIAS, 0))
{
/* subnormal y, shift y to normal. */
while ((hy & (1LL << 48)) == 0)
{
hy = (hy << 1) | (ly >> 63);
ly = ly << 1;
iy -= 1;
}
}
/* fix point fmod */
n = ix - iy;
@ -104,7 +111,7 @@ __ieee754_fmodl (long double x, long double y)
hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
if(hz<0){hx = hx+hx+(lx>>63); lx = lx+lx;}
else {
if((hz|(lz&0x7fffffffffffffff))==0) /* return sign(x)*0 */
if((hz|lz)==0) /* return sign(x)*0 */
return Zero[(u_int64_t)sx>>63];
hx = hz+hz+(lz>>63); lx = lz+lz;
}
@ -113,7 +120,7 @@ __ieee754_fmodl (long double x, long double y)
if(hz>=0) {hx=hz;lx=lz;}
/* convert back to floating value and restore the sign */
if((hx|(lx&0x7fffffffffffffff))==0) /* return sign(x)*0 */
if((hx|lx)==0) /* return sign(x)*0 */
return Zero[(u_int64_t)sx>>63];
while(hx<0x0001000000000000LL) { /* normalize x */
hx = hx+hx+(lx>>63); lx = lx+lx;

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@ -45,76 +45,84 @@
#include <math.h>
#include <math_private.h>
static const long double two600 = 0x1.0p+600L;
static const long double two1022 = 0x1.0p+1022L;
long double
__ieee754_hypotl(long double x, long double y)
{
long double a,b,t1,t2,y1,y2,w,kld;
long double a,b,a1,a2,b1,b2,w,kld;
int64_t j,k,ha,hb;
double xhi, yhi, hi, lo;
GET_LDOUBLE_MSW64(ha,x);
xhi = ldbl_high (x);
EXTRACT_WORDS64 (ha, xhi);
yhi = ldbl_high (y);
EXTRACT_WORDS64 (hb, yhi);
ha &= 0x7fffffffffffffffLL;
GET_LDOUBLE_MSW64(hb,y);
hb &= 0x7fffffffffffffffLL;
if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
a = fabsl(a); /* a <- |a| */
b = fabsl(b); /* b <- |b| */
if((ha-hb)>0x780000000000000LL) {return a+b;} /* x/y > 2**120 */
if((ha-hb)>0x0780000000000000LL) {return a+b;} /* x/y > 2**120 */
k=0;
kld = 1.0L;
if(ha > 0x5f30000000000000LL) { /* a>2**500 */
if(ha >= 0x7ff0000000000000LL) { /* Inf or NaN */
u_int64_t low;
w = a+b; /* for sNaN */
GET_LDOUBLE_LSW64(low,a);
if(((ha&0xfffffffffffffLL)|(low&0x7fffffffffffffffLL))==0)
if(ha == 0x7ff0000000000000LL)
w = a;
GET_LDOUBLE_LSW64(low,b);
if(((hb^0x7ff0000000000000LL)|(low&0x7fffffffffffffffLL))==0)
if(hb == 0x7ff0000000000000LL)
w = b;
return w;
}
/* scale a and b by 2**-600 */
ha -= 0x2580000000000000LL; hb -= 0x2580000000000000LL; k += 600;
a /= two600;
b /= two600;
k += 600;
kld = two600;
a *= 0x1p-600L;
b *= 0x1p-600L;
k = 600;
kld = 0x1p+600L;
}
if(hb < 0x23d0000000000000LL) { /* b < 2**-450 */
else if(hb < 0x23d0000000000000LL) { /* b < 2**-450 */
if(hb <= 0x000fffffffffffffLL) { /* subnormal b or 0 */
u_int64_t low;
GET_LDOUBLE_LSW64(low,b);
if((hb|(low&0x7fffffffffffffffLL))==0) return a;
t1=two1022; /* t1=2^1022 */
b *= t1;
a *= t1;
k -= 1022;
kld = kld / two1022;
if(hb==0) return a;
a *= 0x1p+1022L;
b *= 0x1p+1022L;
k = -1022;
kld = 0x1p-1022L;
} else { /* scale a and b by 2^600 */
ha += 0x2580000000000000LL; /* a *= 2^600 */
hb += 0x2580000000000000LL; /* b *= 2^600 */
k -= 600;
a *= two600;
b *= two600;
kld = kld / two600;
a *= 0x1p+600L;
b *= 0x1p+600L;
k = -600;
kld = 0x1p-600L;
}
}
/* medium size a and b */
w = a-b;
if (w>b) {
SET_LDOUBLE_WORDS64(t1,ha,0);
t2 = a-t1;
w = __ieee754_sqrtl(t1*t1-(b*(-b)-t2*(a+t1)));
ldbl_unpack (a, &hi, &lo);
a1 = hi;
a2 = lo;
/* a*a + b*b
= (a1+a2)*a + b*b
= a1*a + a2*a + b*b
= a1*(a1+a2) + a2*a + b*b
= a1*a1 + a1*a2 + a2*a + b*b
= a1*a1 + a2*(a+a1) + b*b */
w = __ieee754_sqrtl(a1*a1-(b*(-b)-a2*(a+a1)));
} else {
a = a+a;
SET_LDOUBLE_WORDS64(y1,hb,0);
y2 = b - y1;
SET_LDOUBLE_WORDS64(t1,ha+0x0010000000000000LL,0);
t2 = a - t1;
w = __ieee754_sqrtl(t1*y1-(w*(-w)-(t1*y2+t2*b)));
ldbl_unpack (b, &hi, &lo);
b1 = hi;
b2 = lo;
ldbl_unpack (a, &hi, &lo);
a1 = hi;
a2 = lo;
/* a*a + b*b
= a*a + (a-b)*(a-b) - (a-b)*(a-b) + b*b
= a*a + w*w - (a*a - 2*a*b + b*b) + b*b
= w*w + 2*a*b
= w*w + (a1+a2)*b
= w*w + a1*b + a2*b
= w*w + a1*(b1+b2) + a2*b
= w*w + a1*b1 + a1*b2 + a2*b */
w = __ieee754_sqrtl(a1*b1-(w*(-w)-(a1*b2+a2*b)));
}
if(k!=0)
return w*kld;

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@ -33,18 +33,22 @@ __ieee754_remainderl(long double x, long double p)
int64_t hx,hp;
u_int64_t sx,lx,lp;
long double p_half;
double xhi, xlo, phi, plo;
GET_LDOUBLE_WORDS64(hx,lx,x);
GET_LDOUBLE_WORDS64(hp,lp,p);
ldbl_unpack (x, &xhi, &xlo);
EXTRACT_WORDS64 (hx, xhi);
EXTRACT_WORDS64 (lx, xlo);
ldbl_unpack (p, &phi, &plo);
EXTRACT_WORDS64 (hp, phi);
EXTRACT_WORDS64 (lp, plo);
sx = hx&0x8000000000000000ULL;
hp &= 0x7fffffffffffffffLL;
hx &= 0x7fffffffffffffffLL;
/* purge off exception values */
if((hp|(lp&0x7fffffffffffffff))==0) return (x*p)/(x*p); /* p = 0 */
if(hp==0) return (x*p)/(x*p); /* p = 0 */
if((hx>=0x7ff0000000000000LL)|| /* x not finite */
((hp>=0x7ff0000000000000LL)&& /* p is NaN */
(((hp-0x7ff0000000000000LL)|lp)!=0)))
(hp>0x7ff0000000000000LL)) /* p is NaN */
return (x*p)/(x*p);
@ -64,8 +68,8 @@ __ieee754_remainderl(long double x, long double p)
if(x>=p_half) x -= p;
}
}
GET_LDOUBLE_MSW64(hx,x);
SET_LDOUBLE_MSW64(x,hx^sx);
if (sx)
x = -x;
return x;
}
strong_alias (__ieee754_remainderl, __remainderl_finite)

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@ -760,16 +760,16 @@ long double
__erfl (long double x)
{
long double a, y, z;
int32_t i, ix, sign;
ieee854_long_double_shape_type u;
int32_t i, ix, hx;
double xhi;
u.value = x;
sign = u.parts32.w0;
ix = sign & 0x7fffffff;
xhi = ldbl_high (x);
GET_HIGH_WORD (hx, xhi);
ix = hx & 0x7fffffff;
if (ix >= 0x7ff00000)
{ /* erf(nan)=nan */
i = ((sign & 0xfff00000) >> 31) << 1;
i = ((uint32_t) hx >> 31) << 1;
return (long double) (1 - i) + one / x; /* erf(+-inf)=+-1 */
}
@ -778,7 +778,7 @@ __erfl (long double x)
if (ix >= 0x4039A0DE)
{
/* __erfcl (x) underflows if x > 25.6283 */
if (sign)
if ((hx & 0x80000000) == 0)
return one-tiny;
else
return tiny-one;
@ -789,8 +789,9 @@ __erfl (long double x)
return (one - y);
}
}
u.parts32.w0 = ix;
a = u.value;
a = x;
if ((hx & 0x80000000) != 0)
a = -a;
z = x * x;
if (ix < 0x3fec0000) /* a < 0.875 */
{
@ -814,7 +815,7 @@ __erfl (long double x)
y = erf_const + neval (a, TN2, NTN2) / deval (a, TD2, NTD2);
}
if (sign & 0x80000000) /* x < 0 */
if (hx & 0x80000000) /* x < 0 */
y = -y;
return( y );
}
@ -824,18 +825,18 @@ long double
__erfcl (long double x)
{
long double y, z, p, r;
int32_t i, ix, sign;
ieee854_long_double_shape_type u;
int32_t i, ix;
uint32_t hx;
double xhi;
u.value = x;
sign = u.parts32.w0;
ix = sign & 0x7fffffff;
u.parts32.w0 = ix;
xhi = ldbl_high (x);
GET_HIGH_WORD (hx, xhi);
ix = hx & 0x7fffffff;
if (ix >= 0x7ff00000)
{ /* erfc(nan)=nan */
/* erfc(+-inf)=0,2 */
return (long double) (((u_int32_t) sign >> 31) << 1) + one / x;
return (long double) ((hx >> 31) << 1) + one / x;
}
if (ix < 0x3fd00000) /* |x| <1/4 */
@ -846,7 +847,8 @@ __erfcl (long double x)
}
if (ix < 0x3ff40000) /* 1.25 */
{
x = u.value;
if ((hx & 0x80000000) != 0)
x = -x;
i = 8.0 * x;
switch (i)
{
@ -891,7 +893,7 @@ __erfcl (long double x)
y += C20a;
break;
}
if (sign & 0x80000000)
if (hx & 0x80000000)
y = 2.0L - y;
return y;
}
@ -899,10 +901,11 @@ __erfcl (long double x)
if (ix < 0x405ac000)
{
/* x < -9 */
if ((ix >= 0x40220000) && (sign & 0x80000000))
if (hx >= 0xc0220000)
return two - tiny;
x = fabsl (x);
if ((hx & 0x80000000) != 0)
x = -x;
z = one / (x * x);
i = 8.0 / x;
switch (i)
@ -933,21 +936,17 @@ __erfcl (long double x)
p = neval (z, RNr8, NRNr8) / deval (z, RDr8, NRDr8);
break;
}
u.value = x;
u.parts32.w3 = 0;
u.parts32.w2 = 0;
u.parts32.w1 &= 0xf8000000;
z = u.value;
z = (float) x;
r = __ieee754_expl (-z * z - 0.5625) *
__ieee754_expl ((z - x) * (z + x) + p);
if ((sign & 0x80000000) == 0)
if ((hx & 0x80000000) == 0)
return r / x;
else
return two - r / x;
}
else
{
if ((sign & 0x80000000) == 0)
if ((hx & 0x80000000) == 0)
return tiny * tiny;
else
return two - tiny;