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If compiled with z196 zarch support, the convert-to-fixed instruction is used to implement lrint, lrintf, lrintl. Otherwise the common-code implementation is used.
56 lines
1.9 KiB
C
56 lines
1.9 KiB
C
/* lrint() - S390 version.
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Copyright (C) 2019 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifdef HAVE_S390_MIN_Z196_ZARCH_ASM_SUPPORT
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# include <math.h>
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# include <libm-alias-double.h>
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/* The sizeof (long int) differs between s390x (8byte) and s390 (4byte).
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Thus we need different instructions as the target size is encoded there.
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Note: On s390 this instruction is only used if build with -mzarch. */
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# ifdef __s390x__
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# define INSN "cgdbra"
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# else
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# define INSN "cfdbra"
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# endif
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long int
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__lrint (double x)
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{
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long int y;
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/* The z196 zarch "convert to fixed" (cgdbra) instruction is rounding
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according to current rounding mode (M3-field: 0).
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First convert x with suppressed inexact exception and check if the
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resulting value is beyond the target limits (indicated by cc=3;
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Note: a nan is also indicated by cc=3).
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If the resulting value is within the target limits, redo
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without suppressing the inexact exception. */
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__asm__ (INSN " %0,0,%1,4 \n\t"
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"jo 1f \n\t"
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INSN " %0,0,%1,0 \n\t"
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"1:"
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: "=&d" (y) : "f" (x) : "cc");
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return y;
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}
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libm_alias_double (__lrint, lrint)
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#else
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# include <sysdeps/ieee754/dbl-64/s_lrint.c>
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#endif
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