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/* Set FP exception mask and rounding mode.
Copyright (C) 1996-2022 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/>. */
#include <fpu_control.h>
#include <fenv_libc.h>
#define convert_bit(M, F, T) \
((T) < (F) \
? ((M) / ((F) / (T))) & (T) \
: ((M) & (F)) * ((T) / (F)))
void
__setfpucw (fpu_control_t fpu_control)
{
unsigned long fpcr, swcr, fc = (int)fpu_control;
/* ??? If this was a real external interface we'd want to read the current
exception state with __ieee_get_fp_control. But this is an internal
function only called at process startup, so there's no point in trying
to preserve exceptions that cannot have been raised yet. Indeed, this
entire function is likely to be one big nop unless the user overrides
the default __fpu_control variable. */
/* Convert the rounding mode from fpu_control.h format. */
const unsigned long conv_rnd
= ( (FE_TOWARDZERO << (_FPU_RC_ZERO >> 8))
| (FE_DOWNWARD << (_FPU_RC_DOWN >> 8))
| (FE_TONEAREST << (_FPU_RC_NEAREST >> 8))
| (FE_UPWARD << (_FPU_RC_UP >> 8)));
fpcr = ((conv_rnd >> ((fc >> 8) & 3)) & 3) << FPCR_ROUND_SHIFT;
/* Convert the exception mask from fpu_control.h format. */
swcr = convert_bit (~fc, _FPU_MASK_IM, FE_INVALID >> SWCR_ENABLE_SHIFT);
swcr |= convert_bit (~fc, _FPU_MASK_DM, FE_UNDERFLOW >> SWCR_ENABLE_SHIFT);
swcr |= convert_bit (~fc, _FPU_MASK_ZM, FE_DIVBYZERO >> SWCR_ENABLE_SHIFT);
swcr |= convert_bit (~fc, _FPU_MASK_OM, FE_OVERFLOW >> SWCR_ENABLE_SHIFT);
swcr |= convert_bit (~fc, _FPU_MASK_PM, FE_INEXACT >> SWCR_ENABLE_SHIFT);
/* Install everything. */
__fpu_control = fc;
asm volatile ("mt_fpcr %0" : : "f"(fpcr));
__ieee_set_fp_control(swcr);
}
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