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fix a cbrtl.c regression and remove x87 precision setting

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This commit is contained in:
nsz 2012-03-20 15:17:15 +01:00
commit 1e2fea632b
1 changed files with 6 additions and 27 deletions
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33
src/math/cbrtl.c
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@ -23,9 +23,9 @@ long double cbrtl(long double x)
return cbrt(x); return cbrt(x);
} }
#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384 #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
#define BIAS (LDBL_MAX_EXP - 1)
static const unsigned #define BIAS (LDBL_MAX_EXP - 1)
B1 = 709958130; /* B1 = (127-127.0/3-0.03306235651)*2**23 */ static const unsigned B1 = 709958130; /* B1 = (127-127.0/3-0.03306235651)*2**23 */
long double cbrtl(long double x) long double cbrtl(long double x)
{ {
@ -48,25 +48,10 @@ long double cbrtl(long double x)
if (k == BIAS + LDBL_MAX_EXP) if (k == BIAS + LDBL_MAX_EXP)
return x + x; return x + x;
// FIXME: extended precision is default on linux..
#undef __i386__
#ifdef __i386__
fp_prec_t oprec;
oprec = fpgetprec();
if (oprec != FP_PE)
fpsetprec(FP_PE);
#endif
if (k == 0) { if (k == 0) {
/* If x = +-0, then cbrt(x) = +-0. */ /* If x = +-0, then cbrt(x) = +-0. */
if ((u.bits.manh | u.bits.manl) == 0) { if ((u.bits.manh | u.bits.manl) == 0)
#ifdef __i386__ return x;
if (oprec != FP_PE)
fpsetprec(oprec);
#endif
return (x);
}
/* Adjust subnormal numbers. */ /* Adjust subnormal numbers. */
u.e *= 0x1.0p514; u.e *= 0x1.0p514;
k = u.bits.exp; k = u.bits.exp;
@ -118,7 +103,7 @@ long double cbrtl(long double x)
* Round it away from zero to 32 bits (32 so that t*t is exact, and * Round it away from zero to 32 bits (32 so that t*t is exact, and
* away from zero for technical reasons). * away from zero for technical reasons).
*/ */
t = dt + (0x1.0p32L + 0x1.0p-32L) - 0x1.0p32; t = dt + (0x1.0p32L + 0x1.0p-31L) - 0x1.0p32;
#elif LDBL_MANT_DIG == 113 #elif LDBL_MANT_DIG == 113
/* /*
* Round dt away from zero to 47 bits. Since we don't trust the 47, * Round dt away from zero to 47 bits. Since we don't trust the 47,
@ -129,8 +114,6 @@ long double cbrtl(long double x)
* dt is much more accurate than needed. * dt is much more accurate than needed.
*/ */
t = dt + 0x2.0p-46 + 0x1.0p60L - 0x1.0p60; t = dt + 0x2.0p-46 + 0x1.0p60L - 0x1.0p60;
#else
#error "Unsupported long double format"
#endif #endif
/* /*
@ -144,10 +127,6 @@ long double cbrtl(long double x)
t = t+t*r; /* error <= 0.5 + 0.5/3 + epsilon */ t = t+t*r; /* error <= 0.5 + 0.5/3 + epsilon */
t *= v.e; t *= v.e;
#ifdef __i386__
if (oprec != FP_PE)
fpsetprec(oprec);
#endif
return t; return t;
} }
#endif #endif