diff options
Diffstat (limited to 'sysdeps/ieee754/ldbl-128ibm/s_roundl.c')
| -rw-r--r-- | sysdeps/ieee754/ldbl-128ibm/s_roundl.c | 76 |
1 files changed, 39 insertions, 37 deletions
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_roundl.c b/sysdeps/ieee754/ldbl-128ibm/s_roundl.c index 20813ed366..94a62dcd6c 100644 --- a/sysdeps/ieee754/ldbl-128ibm/s_roundl.c +++ b/sysdeps/ieee754/ldbl-128ibm/s_roundl.c @@ -1,6 +1,6 @@ /* Round to int long double floating-point values. IBM extended format long double version. - Copyright (C) 2006-2016 Free Software Foundation, Inc. + Copyright (C) 2006-2018 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 @@ -21,6 +21,7 @@ when it's coded in C. */ #include <math.h> +#include <math_private.h> #include <math_ldbl_opt.h> #include <float.h> #include <ieee754.h> @@ -38,47 +39,48 @@ __roundl (long double x) && __builtin_isless (__builtin_fabs (xh), __builtin_inf ()), 1)) { - double orig_xh; - - /* Long double arithmetic, including the canonicalisation below, - only works in round-to-nearest mode. */ - - /* Convert the high double to integer. */ - orig_xh = xh; - hi = ldbl_nearbyint (xh); - - /* Subtract integral high part from the value. */ - xh -= hi; - ldbl_canonicalize (&xh, &xl); - - /* Now convert the low double, adjusted for any remainder from the - high double. */ - lo = ldbl_nearbyint (xh); - - /* Adjust the result when the remainder is exactly 0.5. nearbyint - rounds values halfway between integers to the nearest even - integer. roundl must round away from zero. - Also correct cases where nearbyint returns an incorrect value - for LO. */ - xh -= lo; - ldbl_canonicalize (&xh, &xl); - if (xh == 0.5) + hi = __round (xh); + if (hi != xh) { - if (xl > 0.0 || (xl == 0.0 && orig_xh > 0.0)) - lo += 1.0; + /* The high part is not an integer; the low part only + affects the result if the high part is exactly half way + between two integers and the low part is nonzero with the + opposite sign. */ + if (fabs (hi - xh) == 0.5) + { + if (xh > 0 && xl < 0) + xh = hi - 1; + else if (xh < 0 && xl > 0) + xh = hi + 1; + else + xh = hi; + } + else + xh = hi; + xl = 0; } - else if (-xh == 0.5) + else { - if (xl < 0.0 || (xl == 0.0 && orig_xh < 0.0)) - lo -= 1.0; + /* The high part is a nonzero integer. */ + lo = __round (xl); + if (fabs (lo - xl) == 0.5) + { + if (xh > 0 && xl < 0) + xl = lo + 1; + else if (xh < 0 && lo > 0) + xl = lo - 1; + else + xl = lo; + } + else + xl = lo; + xh = hi; + ldbl_canonicalize_int (&xh, &xl); } - - /* Ensure the final value is canonical. In certain cases, - rounding causes hi,lo calculated so far to be non-canonical. */ - xh = hi; - xl = lo; - ldbl_canonicalize (&xh, &xl); } + else + /* Quiet signaling NaN arguments. */ + xh += xh; return ldbl_pack (xh, xl); } |