1/* llrint() - 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 <libm-alias-double.h>
27
28long long int
29__llrint (double x)
30{
31 long long int y;
32 /* The z196 zarch "convert to fixed" (cgdbra) instruction is rounding
33 according to current rounding mode (M3-field: 0).
34 First convert x with suppressed inexact exception and check if the
35 resulting value is beyond the target limits (indicated by cc=3;
36 Note: a nan is also indicated by cc=3).
37 If the resulting value is within the target limits, redo
38 without suppressing the inexact exception. */
39 __asm__ ("cgdbra %0,0,%1,4 \n\t"
40 "jo 1f \n\t"
41 "cgdbra %0,0,%1,0 \n\t"
42 "1:"
43 : "=&d" (y) : "f" (x) : "cc");
44 return y;
45}
46libm_alias_double (__llrint, llrint)
47
48#else
49# include <sysdeps/ieee754/dbl-64/s_llrint.c>
50#endif
51

source code of glibc/sysdeps/s390/fpu/s_llrint.c