diff options
Diffstat (limited to 'REORG.TODO/sysdeps/ieee754/ldbl-128ibm/s_frexpl.c')
| -rw-r--r-- | REORG.TODO/sysdeps/ieee754/ldbl-128ibm/s_frexpl.c | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/ieee754/ldbl-128ibm/s_frexpl.c b/REORG.TODO/sysdeps/ieee754/ldbl-128ibm/s_frexpl.c new file mode 100644 index 0000000000..210c5d2ed4 --- /dev/null +++ b/REORG.TODO/sysdeps/ieee754/ldbl-128ibm/s_frexpl.c @@ -0,0 +1,148 @@ +/* s_frexpl.c -- long double version of s_frexp.c. + * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz. + */ + +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunPro, a Sun Microsystems, Inc. business. + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + +#if defined(LIBM_SCCS) && !defined(lint) +static char rcsid[] = "$NetBSD: $"; +#endif + +/* + * for non-zero x + * x = frexpl(arg,&exp); + * return a long double fp quantity x such that 0.5 <= |x| <1.0 + * and the corresponding binary exponent "exp". That is + * arg = x*2^exp. + * If arg is inf, 0.0, or NaN, then frexpl(arg,&exp) returns arg + * with *exp=0. + */ + +#include <math.h> +#include <math_private.h> +#include <math_ldbl_opt.h> + +long double __frexpl(long double x, int *eptr) +{ + uint64_t hx, lx, ix, ixl; + int64_t explo, expon; + double xhi, xlo; + + ldbl_unpack (x, &xhi, &xlo); + EXTRACT_WORDS64 (hx, xhi); + EXTRACT_WORDS64 (lx, xlo); + ixl = 0x7fffffffffffffffULL & lx; + ix = 0x7fffffffffffffffULL & hx; + expon = 0; + if (ix >= 0x7ff0000000000000ULL || ix == 0) + { + /* 0,inf,nan. */ + *eptr = expon; + return x + x; + } + expon = ix >> 52; + if (expon == 0) + { + /* Denormal high double, the low double must be 0.0. */ + int cnt; + + /* Normalize. */ + if (sizeof (ix) == sizeof (long)) + cnt = __builtin_clzl (ix); + else if ((ix >> 32) != 0) + cnt = __builtin_clzl ((long) (ix >> 32)); + else + cnt = __builtin_clzl ((long) ix) + 32; + cnt = cnt - 12; + expon -= cnt; + ix <<= cnt + 1; + } + expon -= 1022; + ix &= 0x000fffffffffffffULL; + hx &= 0x8000000000000000ULL; + hx |= (1022LL << 52) | ix; + + if (ixl != 0) + { + /* If the high double is an exact power of two and the low + double has the opposite sign, then the exponent calculated + from the high double is one too big. */ + if (ix == 0 + && (int64_t) (hx ^ lx) < 0) + { + hx += 1LL << 52; + expon -= 1; + } + + explo = ixl >> 52; + if (explo == 0) + { + /* The low double started out as a denormal. Normalize its + mantissa and adjust the exponent. */ + int cnt; + + if (sizeof (ixl) == sizeof (long)) + cnt = __builtin_clzl (ixl); + else if ((ixl >> 32) != 0) + cnt = __builtin_clzl ((long) (ixl >> 32)); + else + cnt = __builtin_clzl ((long) ixl) + 32; + cnt = cnt - 12; + explo -= cnt; + ixl <<= cnt + 1; + } + + /* With variable precision we can't assume much about the + magnitude of the returned low double. It may even be a + denormal. */ + explo -= expon; + ixl &= 0x000fffffffffffffULL; + lx &= 0x8000000000000000ULL; + if (explo <= 0) + { + /* Handle denormal low double. */ + if (explo > -52) + { + ixl |= 1LL << 52; + ixl >>= 1 - explo; + } + else + { + ixl = 0; + lx = 0; + if ((hx & 0x7ff0000000000000ULL) == (1023LL << 52)) + { + /* Oops, the adjustment we made above for values a + little smaller than powers of two turned out to + be wrong since the returned low double will be + zero. This can happen if the input was + something weird like 0x1p1000 - 0x1p-1000. */ + hx -= 1LL << 52; + expon += 1; + } + } + explo = 0; + } + lx |= (explo << 52) | ixl; + } + + INSERT_WORDS64 (xhi, hx); + INSERT_WORDS64 (xlo, lx); + x = ldbl_pack (xhi, xlo); + *eptr = expon; + return x; +} +#if IS_IN (libm) +long_double_symbol (libm, __frexpl, frexpl); +#else +long_double_symbol (libc, __frexpl, frexpl); +#endif |