diff options
Diffstat (limited to 'sysdeps/ieee754/ldbl-128ibm/s_roundl.c')
| -rw-r--r-- | sysdeps/ieee754/ldbl-128ibm/s_roundl.c | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_roundl.c b/sysdeps/ieee754/ldbl-128ibm/s_roundl.c new file mode 100644 index 0000000..7fe84b8 --- /dev/null +++ b/sysdeps/ieee754/ldbl-128ibm/s_roundl.c @@ -0,0 +1,120 @@ +/* Round to int long double floating-point values. + IBM extended format long double version. + Copyright (C) 2006 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +/* This has been coded in assembler because GCC makes such a mess of it + when it's coded in C. */ + +#include <math.h> +#include <fenv.h> +#include <math_ldbl_opt.h> +#include <float.h> +#include <ieee754.h> + + +#ifdef __STDC__ +long double +__roundl (long double x) +#else +long double +__roundl (x) + long double x; +#endif +{ + static const double TWO52 = 4503599627370496.0; + static const double HALF = 0.5; + int mode = fegetround(); + union ibm_extended_long_double u; + u.d = x; + + if (fabs (u.dd[0]) < TWO52) + { + fesetround(FE_TOWARDZERO); + if (u.dd[0] > 0.0) + { + u.dd[0] += HALF; + u.dd[0] += TWO52; + u.dd[0] -= TWO52; + } + else if (u.dd[0] < 0.0) + { + u.dd[0] = TWO52 - (u.dd[0] - HALF); + u.dd[0] = -(u.dd[0] - TWO52); + } + u.dd[1] = 0.0; + fesetround(mode); + } + else if (fabs (u.dd[1]) < TWO52 && u.dd[1] != 0.0) + { + double high, low; + /* In this case we have to round the low double and handle any + adjustment to the high double that may be caused by rounding + (up). This is complicated by the fact that the high double + may already be rounded and the low double may have the + opposite sign to compensate. */ + if (u.dd[0] > 0.0) + { + if (u.dd[1] > 0.0) + { + /* If the high/low doubles are the same sign then simply + round the low double. */ + high = u.dd[0]; + low = u.dd[1]; + } + else if (u.dd[1] < 0.0) + { + /* Else the high double is pre rounded and we need to + adjust for that. */ + high = nextafter (u.dd[0], 0.0); + low = u.dd[1] + (u.dd[0] - high); + } + fesetround(FE_TOWARDZERO); + low += HALF; + low += TWO52; + low -= TWO52; + } + else if (u.dd[0] < 0.0) + { + if (u.dd[1] < 0.0) + { + /* If the high/low doubles are the same sign then simply + round the low double. */ + high = u.dd[0]; + low = u.dd[1]; + } + else if (u.dd[1] > 0.0) + { + /* Else the high double is pre rounded and we need to + adjust for that. */ + high = nextafter (u.dd[0], 0.0); + low = u.dd[1] + (u.dd[0] - high); + } + fesetround(FE_TOWARDZERO); + low -= HALF; + low = TWO52 - low; + low = -(low - TWO52); + } + fesetround(mode); + u.dd[0] = high + low; + u.dd[1] = high - u.dd[0] + low; + } + return u.d; +} + +long_double_symbol (libm, __roundl, roundl); |