glibc/sysdeps/s390/fpu/s_llround.c
Stefan Liebler 7d42d614fd S390: Use convert-to-fixed instruction for llround functions.
If compiled with z196 zarch support, the convert-to-fixed instruction
is used to implement llround, llroundf, llroundl.
Otherwise the common-code implementation is used.
2019-12-11 15:12:24 +01:00

43 lines
1.6 KiB
C

/* llround() - S390 version.
Copyright (C) 2019 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, see
<https://www.gnu.org/licenses/>. */
#if defined __s390x__ && defined HAVE_S390_MIN_Z196_ZARCH_ASM_SUPPORT
/* We only support s390x as on s390 a long long int refers to a register pair
of two 4byte registers instead of a 8byte register which is produced by the
instruction.
Note: On s390 this instruction would only be used if build with -mzarch. */
# include <math.h>
# include <libm-alias-double.h>
long long int
__llround (double x)
{
long long int y;
/* The z196 zarch "convert to fixed" (cgdbra) instruction is rounding
x to the nearest integer with "ties away from 0" rounding mode
(M3-field: 1) where inexact exceptions are suppressed (M4-field: 4). */
__asm__ ("cgdbra %0,1,%1,4" : "=d" (y) : "f" (x) : "cc");
return y;
}
libm_alias_double (__llround, llround)
#else
# include <sysdeps/ieee754/dbl-64/s_llround.c>
#endif