sysdeps/s390/fpu/s_llrintl.c

   1 /* llrintl() - S390 version.
   2    Copyright (C) 2019-2024 Free Software Foundation, Inc.
   3
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public License as
   8    published by the Free Software Foundation; either version 2.1 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #if defined __s390x__ && defined HAVE_S390_MIN_Z196_ZARCH_ASM_SUPPORT
  21 /* We only support s390x as on s390 a long long int refers to a register pair
  22    of two 4byte registers instead of a 8byte register which is produced by the
  23    instruction.
  24    Note: On s390 this instruction would only be used if build with -mzarch.  */
  25 # include <math.h>
  26 # include <math_private.h>
  27 # include <libm-alias-ldouble.h>
  28
  29 long long int
  30 __llrintl (_Float128 x)
  31 {
  32   long long int y;
  33   /* The z196 zarch "convert to fixed" (cgxbra) instruction is rounding
  34      according to current rounding mode (M3-field: 0).
  35      First convert x with suppressed inexact exception and check if the
  36      resulting value is beyond the target limits (indicated by cc=3;
  37      Note: a nan is also indicated by cc=3).
  38      If the resulting value is within the target limits, redo
  39      without suppressing the inexact exception.  */
  40   __asm__ ("cgxbra %0,0,%1,4 \n\t"
  41            "jo 1f \n\t"
  42            "cgxbra %0,0,%1,0 \n\t"
  43            "1:"
  44            : "=&d" (y) : "f" (x) : "cc");
  45   return y;
  46 }
  47 libm_alias_ldouble (__llrint, llrint)
  48
  49 #else
  50 # include <sysdeps/ieee754/ldbl-128/s_llrintl.c>
  51 #endif