/* $NetBSD: fenv.c,v 1.4 2021/09/03 21:54:59 andvar Exp $ */
/*-
* Copyright (c) 2004-2005 David Schultz <das@FreeBSD.ORG>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: fenv.c,v 1.4 2021/09/03 21:54:59 andvar Exp $");
#include "namespace.h"
#include <assert.h>
#include <fenv.h>
#ifdef __weak_alias
__weak_alias(feclearexcept,_feclearexcept)
__weak_alias(fedisableexcept,_fedisableexcept)
__weak_alias(feenableexcept,_feenableexcept)
__weak_alias(fegetenv,_fegetenv)
__weak_alias(fegetexcept,_fegetexcept)
__weak_alias(fegetexceptflag,_fegetexceptflag)
__weak_alias(fegetround,_fegetround)
__weak_alias(feholdexcept,_feholdexcept)
__weak_alias(feraiseexcept,_feraiseexcept)
__weak_alias(fesetenv,_fesetenv)
__weak_alias(fesetexceptflag,_fesetexceptflag)
__weak_alias(fesetround,_fesetround)
__weak_alias(fetestexcept,_fetestexcept)
__weak_alias(feupdateenv,_feupdateenv)
#endif
#ifdef __arch64__
/* Load floating-point state register (all 64bits) */
#define __ldxfsr(__r) __asm__ __volatile__ \
("ldx %0, %%fsr" : : "m" (__r))
/* Save floating-point state register (all 64bits) */
#define __stxfsr(__r) __asm__ __volatile__ \
("stx %%fsr, %0" : "=m" (*(__r)))
#else /* !__arch64__ */
/* Load floating-point state register (32bits) */
#define __ldxfsr(__r) __asm__ __volatile__ \
("ld %0, %%fsr" : : "m" (__r))
/* Save floating-point state register (32bits) */
#define __stxfsr(__r) __asm__ __volatile__ \
("st %%fsr, %0" : "=m" (*(__r)))
#endif /* __arch64__ */
/*
* The feclearexcept() function clears the supported floating-point exceptions
* represented by `excepts'.
*/
int
feclearexcept(int excepts)
{
fexcept_t r;
int ex;
_DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
ex = excepts & FE_ALL_EXCEPT;
__stxfsr(&r);
r &= ~ex;
__ldxfsr(r);
/* Success */
return 0;
}
/*
* The fegetexceptflag() function stores an implementation-defined
* representation of the states of the floating-point status flags indicated
* by the argument excepts in the object pointed to by the argument flagp.
*/
int
fegetexceptflag(fexcept_t *flagp, int excepts)
{
fexcept_t r;
int ex;
_DIAGASSERT(flagp != NULL);
_DIAGASSERT((excepts & ~_FE_ALL_EXCEPT) == 0);
ex = excepts & FE_ALL_EXCEPT;
__stxfsr(&r);
*flagp = r & ex;
/* Success */
return 0;
}
/*
* This function sets the floating-point status flags indicated by the argument
* `excepts' to the states stored in the object pointed to by `flagp'. It does
* NOT raise any floating-point exceptions, but only sets the state of the flags.
*/
int
fesetexceptflag(const fexcept_t *flagp, int excepts)
{
fexcept_t r;
int ex;
_DIAGASSERT(flagp != NULL);
_DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
ex = excepts & FE_ALL_EXCEPT;
__stxfsr(&r);
r &= ~ex;
r |= *flagp & ex;
__ldxfsr(r);
/* Success */
return 0;
}
/*
* The feraiseexcept() function raises the supported floating-point exceptions
* represented by the argument `excepts'.
*
* The order in which these floating-point exceptions are raised is unspecified
* (by the standard).
*/
int
feraiseexcept(int excepts)
{
volatile double d;
int ex;
_DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
ex = excepts & FE_ALL_EXCEPT;
/*
* With a compiler that supports the FENV_ACCESS pragma properly, simple
* expressions like '0.0 / 0.0' should be sufficient to generate traps.
* Unfortunately, we need to bring a volatile variable into the equation
* to prevent incorrect optimizations.
*/
if (ex & FE_INVALID) {
d = 0.0;
d = 0.0 / d;
}
if (ex & FE_DIVBYZERO) {
d = 0.0;
d = 1.0 / d;
}
if (ex & FE_OVERFLOW) {
d = 0x1.ffp1023;
d *= 2.0;
}
if (ex & FE_UNDERFLOW) {
d = 0x1p-1022;
d /= 0x1p1023;
}
if (ex & FE_INEXACT) {
d = 0x1p-1022;
d += 1.0;
}
/* Success */
return 0;
}
/*
* The fetestexcept() function determines which of a specified subset of the
* floating-point exception flags are currently set. The `excepts' argument
* specifies the floating-point status flags to be queried.
*/
int
fetestexcept(int excepts)
{
fexcept_t r;
_DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
__stxfsr(&r);
return r & (excepts & FE_ALL_EXCEPT);
}
/*
* The fegetround() function gets the current rounding direction.
*/
int
fegetround(void)
{
fenv_t r;
__stxfsr(&r);
return (r >> _ROUND_SHIFT) & _ROUND_MASK;
}
/*
* The fesetround() function establishes the rounding direction represented by
* its argument `round'. If the argument is not equal to the value of a rounding
* direction macro, the rounding direction is not changed.
*/
int
fesetround(int round)
{
fenv_t r;
_DIAGASSERT((round & ~_ROUND_MASK) == 0);
if (round & ~_ROUND_MASK)
return -1;
__stxfsr(&r);
r &= ~(_ROUND_MASK << _ROUND_SHIFT);
r |= round << _ROUND_SHIFT;
__ldxfsr(r);
/* Success */
return 0;
}
/*
* The fegetenv() function attempts to store the current floating-point
* environment in the object pointed to by envp.
*/
int
fegetenv(fenv_t *envp)
{
_DIAGASSERT(envp != NULL);
__stxfsr(envp);
/* Success */
return 0;
}
/*
* The feholdexcept() function saves the current floating-point environment
* in the object pointed to by envp, clears the floating-point status flags, and
* then installs a non-stop (continue on floating-point exceptions) mode, if
* available, for all floating-point exceptions.
*/
int
feholdexcept(fenv_t *envp)
{
fenv_t r;
_DIAGASSERT(envp != NULL);
__stxfsr(&r);
*envp = r;
r &= ~(FE_ALL_EXCEPT | _ENABLE_MASK);
__ldxfsr(r);
/* Success */
return 0;
}
/*
* The fesetenv() function attempts to establish the floating-point environment
* represented by the object pointed to by envp. The argument `envp' points
* to an object set by a call to fegetenv() or feholdexcept(), or equal a
* floating-point environment macro. The fesetenv() function does not raise
* floating-point exceptions, but only installs the state of the floating-point
* status flags represented through its argument.
*/
int
fesetenv(const fenv_t *envp)
{
_DIAGASSERT(envp != NULL);
__ldxfsr(*envp);
/* Success */
return 0;
}
/*
* The feupdateenv() function saves the currently raised floating-point
* exceptions in its automatic storage, installs the floating-point environment
* represented by the object pointed to by `envp', and then raises the saved
* floating-point exceptions. The argument `envp' shall point to an object set
* by a call to feholdexcept() or fegetenv(), or equal a floating-point
* environment macro.
*/
int
feupdateenv(const fenv_t *envp)
{
fexcept_t r;
_DIAGASSERT(envp != NULL);
__stxfsr(&r);
__ldxfsr(*envp);
_DIAGASSERT((r & ~FE_ALL_EXCEPT) == 0);
feraiseexcept(r & FE_ALL_EXCEPT);
/* Success */
return 0;
}
/*
* The following functions are extensions to the standard
*/
int
feenableexcept(int mask)
{
fenv_t old_r, new_r;
__stxfsr(&old_r);
new_r = old_r | ((mask & FE_ALL_EXCEPT) << _FPUSW_SHIFT);
__ldxfsr(new_r);
return (old_r >> _FPUSW_SHIFT) & FE_ALL_EXCEPT;
}
int
fedisableexcept(int mask)
{
fenv_t old_r, new_r;
__stxfsr(&old_r);
new_r = old_r & ~((mask & FE_ALL_EXCEPT) << _FPUSW_SHIFT);
__ldxfsr(new_r);
return (old_r >> _FPUSW_SHIFT) & FE_ALL_EXCEPT;
}
int
fegetexcept(void)
{
fenv_t r;
__stxfsr(&r);
return (r & _ENABLE_MASK) >> _FPUSW_SHIFT;
}