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/* Round to integer type (C23 version). Common helper functions.
Copyright (C) 2016-2026 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 <errno.h>
#include <fenv.h>
#include <float.h>
#include <math.h>
#include <math-barriers.h>
#include <stdbool.h>
#include <stdint.h>
/* The including file should have defined UNSIGNED to 0 (signed return
type) or 1 (unsigned return type), INEXACT to 0 (no inexact
exceptions) or 1 (raise inexact exceptions), FLOAT to the floating
type for the function being defined, PREFIX to the prefix of
<float.h> macros for that type and SUFFIX to the suffix of <math.h>
functions for that type. */
#define M_CONCATX(X, Y) X ## Y
#define M_CONCAT(X, Y) M_CONCATX (X, Y)
#define M_SUF(F) M_CONCAT (F, SUFFIX)
#define M_MAX_EXP M_CONCAT (PREFIX, MAX_EXP)
/* Adjust WIDTH into a range sufficient to cover all possible finite
results from calls to this function. */
static unsigned int
fromfp_adjust_width (unsigned int width)
{
if (width > (UNSIGNED ? M_MAX_EXP : M_MAX_EXP + 1))
return UNSIGNED ? M_MAX_EXP : M_MAX_EXP + 1;
return width;
}
/* Return the maximum unbiased exponent for a rounded result (negative
if NEGATIVE is set) that might be in range for a call to a fromfp
function with width WIDTH (greater than 0, and not exceeding that
returned by fromfp_adjust_width). The result may still be out of
range in the case of negative arguments. */
static int
fromfp_max_exponent (bool negative, int width)
{
if (UNSIGNED)
return negative ? -1 : width - 1;
else
return negative ? width - 1 : width - 2;
}
/* Return the result of rounding an argument X in the rounding
direction ROUND. */
static FLOAT
fromfp_round (FLOAT x, int rm)
{
switch (rm)
{
case FP_INT_UPWARD:
return M_SUF (ceil) (x);
case FP_INT_DOWNWARD:
return M_SUF (floor) (x);
case FP_INT_TOWARDZERO:
default:
/* Unknown rounding directions are defined to mean unspecified
rounding; treat this as truncation. */
return M_SUF (trunc) (x);
case FP_INT_TONEARESTFROMZERO:
return M_SUF (round) (x);
case FP_INT_TONEAREST:
return M_SUF (roundeven) (x);
}
}
/* Handle a domain error for a call to a fromfp function. */
static FLOAT
fromfp_domain_error (void)
{
__set_errno (EDOM);
return (FLOAT) 0 / (FLOAT) 0;
}
/* X has rounded to RX, which is within range. Return RX, with
"inexact" raised if appropriate. */
static FLOAT
fromfp_return (FLOAT x, FLOAT rx)
{
if (INEXACT && rx != x)
{
/* There is no need for this to use the specific floating-point
type for which this header is included (and indeed 1 +
LDBL_MIN may not raise "inexact" for IBM long double). */
float force_inexact = 1.0f + FLT_MIN;
math_force_eval (force_inexact);
}
return rx;
}
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