/* $OpenBSD: fenv.c,v 1.7 2022/12/27 17:10:07 jmc Exp $ */ /* $NetBSD: fenv.c,v 1.1 2011/01/31 00:19:33 christos 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 <fenv.h> /* * The following constant represents the default floating-point environment * (that is, the one installed at program startup) and has type pointer to * const-qualified fenv_t. * * It can be used as an argument to the functions within the <fenv.h> header * that manage the floating-point environment, namely fesetenv() and * feupdateenv(). */ fenv_t __fe_dfl_env = 0; /* * The feclearexcept() function clears the supported floating-point exceptions * represented by `excepts'. */ int feclearexcept(int excepts) { fexcept_t r; excepts &= FE_ALL_EXCEPT; /* Save floating-point state register */ __asm__ volatile ("stx %%fsr, %0" : "=m" (r)); r &= ~excepts; /* Load floating-point state register */ __asm__ volatile ("ldx %0, %%fsr" : : "m" (r)); return 0; } DEF_STD(feclearexcept); /* * 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; excepts &= FE_ALL_EXCEPT; /* Save floating-point state register */ __asm__ volatile ("stx %%fsr, %0" : "=m" (r)); *flagp = r & excepts; 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; excepts &= FE_ALL_EXCEPT; /* Save floating-point state register */ __asm__ volatile ("stx %%fsr, %0" : "=m" (r)); r &= ~excepts; r |= *flagp & excepts; /* Load floating-point state register */ __asm__ volatile ("ldx %0, %%fsr" : : "m" (r)); return 0; } DEF_STD(fesetexceptflag); /* * 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; 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 (excepts & FE_INVALID) { d = 0.0; d = 0.0 / d; } if (excepts & FE_DIVBYZERO) { d = 0.0; d = 1.0 / d; } if (excepts & FE_OVERFLOW) { d = 0x1.ffp1023; d *= 2.0; } if (excepts & FE_UNDERFLOW) { d = 0x1p-1022; d /= 0x1p1023; } if (excepts & FE_INEXACT) { d = 0x1p-1022; d += 1.0; } return 0; } DEF_STD(feraiseexcept); /* * 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; excepts &= FE_ALL_EXCEPT; /* Save floating-point state register */ __asm__ volatile ("stx %%fsr, %0" : "=m" (r)); return r & excepts; } DEF_STD(fetestexcept); /* * The fegetround() function gets the current rounding direction. */ int fegetround(void) { fenv_t r; /* Save floating-point state register */ __asm__ volatile ("stx %%fsr, %0" : "=m" (r)); return (r >> _ROUND_SHIFT) & _ROUND_MASK; } DEF_STD(fegetround); /* * 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; if (round & ~_ROUND_MASK) return -1; /* Save floating-point state register */ __asm__ volatile ("stx %%fsr, %0" : "=m" (r)); r &= ~(_ROUND_MASK << _ROUND_SHIFT); r |= round << _ROUND_SHIFT; /* Load floating-point state register */ __asm__ volatile ("ldx %0, %%fsr" : : "m" (r)); return 0; } DEF_STD(fesetround); /* * The fegetenv() function attempts to store the current floating-point * environment in the object pointed to by envp. */ int fegetenv(fenv_t *envp) { /* Save floating-point state register */ __asm__ volatile ("stx %%fsr, %0" : "=m" (*envp)); return 0; } DEF_STD(fegetenv); /* * 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; /* Save floating-point state register */ __asm__ volatile ("stx %%fsr, %0" : "=m" (r)); *envp = r; r &= ~(FE_ALL_EXCEPT | (FE_ALL_EXCEPT << _MASK_SHIFT)); /* Load floating-point state register */ __asm__ volatile ("ldx %0, %%fsr" : : "m" (r)); return 0; } DEF_STD(feholdexcept); /* * 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) { /* Load floating-point state register */ __asm__ volatile ("ldx %0, %%fsr" : : "m" (*envp)); return 0; } DEF_STD(fesetenv); /* * 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; /* Save floating-point state register */ __asm__ volatile ("stx %%fsr, %0" : "=m" (r)); /* Load floating-point state register */ __asm__ volatile ("ldx %0, %%fsr" : : "m" (*envp)); feraiseexcept(r & FE_ALL_EXCEPT); return 0; } DEF_STD(feupdateenv); /* * The following functions are extensions to the standard */ int feenableexcept(int mask) { fenv_t old_r, new_r; mask &= FE_ALL_EXCEPT; /* Save floating-point state register */ __asm__ volatile ("stx %%fsr, %0" : "=m" (old_r)); new_r = old_r | (mask << _MASK_SHIFT); /* Load floating-point state register */ __asm__ volatile ("ldx %0, %%fsr" : : "m" (new_r)); return (old_r >> _MASK_SHIFT) & FE_ALL_EXCEPT; } int fedisableexcept(int mask) { fenv_t old_r, new_r; mask &= FE_ALL_EXCEPT; /* Save floating-point state register */ __asm__ volatile ("stx %%fsr, %0" : "=m" (old_r)); new_r = old_r & ~(mask << _MASK_SHIFT); /* Load floating-point state register */ __asm__ volatile ("ldx %0, %%fsr" : : "m" (new_r)); return (old_r >> _MASK_SHIFT) & FE_ALL_EXCEPT; } int fegetexcept(void) { fenv_t r; /* Save floating-point state register */ __asm__ volatile ("stx %%fsr, %0" : "=m" (r)); return (r & (FE_ALL_EXCEPT << _MASK_SHIFT)) >> _MASK_SHIFT; }
