/* $NetBSD: fenv.c,v 1.4 2017/03/22 23:11:08 chs Exp $ */ /*- * Copyright (c) 2004-2005 David Schultz * 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 __RCSID("$NetBSD: fenv.c,v 1.4 2017/03/22 23:11:08 chs Exp $"); #include "namespace.h" #include #include #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 /* * Convert from exception flags (__BITS(27,32)) to exception enable bits * (__BITS(5,0)) by right-shifting this much: */ #define FE_FLAGS_SHIFT 27 /* * Mask all rounding mode bits */ #define FE_ROUND_MASK (FE_TONEAREST | FE_DOWNWARD | \ FE_UPWARD | FE_TOWARDZERO) /* Load lower 32 bits from floating-point state register */ static inline uint32_t readfpsr(void) { uint32_t rv; __asm__ __volatile__ ("fstw %%fr0, 0(%1)" : "=m" (rv) : "r"(&rv)); return rv; } /* Save floating-point state register */ static inline void writefpsr(uint32_t val) { __asm__ __volatile__("fldw 0(%1),%%fr0" : : "m" (val), "r"(&val)); } /* * 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) << FE_FLAGS_SHIFT; r = readfpsr(); r &= ~ex; writefpsr(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) << FE_FLAGS_SHIFT; r = readfpsr(); *flagp = (r & ex) >> FE_FLAGS_SHIFT; /* 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) << FE_FLAGS_SHIFT; r = readfpsr(); r &= ~ex; r |= (*flagp << FE_FLAGS_SHIFT) & ex; writefpsr(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); r = readfpsr(); return (r >> FE_FLAGS_SHIFT) & (excepts & FE_ALL_EXCEPT); } /* * The fegetround() function gets the current rounding direction. */ int fegetround(void) { fenv_t r; r = readfpsr(); return r & FE_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 & ~FE_ROUND_MASK) == 0); if (round & ~FE_ROUND_MASK) return -1; r = readfpsr(); r &= ~FE_ROUND_MASK; r |= round; writefpsr(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); *envp = readfpsr(); /* 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); r = readfpsr(); *envp = r; r &= ~FE_ALL_EXCEPT; writefpsr(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); writefpsr(*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); r = readfpsr(); writefpsr(*envp); _DIAGASSERT((r & ~FE_ALL_EXCEPT) == 0); feraiseexcept(r & FE_ALL_EXCEPT); /* Success */ return 0; } /* * The following functions are extentions to the standard */ int feenableexcept(int mask) { fenv_t old_r, new_r; old_r = readfpsr(); new_r = old_r | (mask & FE_ALL_EXCEPT); writefpsr(new_r); return old_r & FE_ALL_EXCEPT; } int fedisableexcept(int mask) { fenv_t old_r, new_r; old_r = readfpsr(); new_r = old_r & ~(mask & FE_ALL_EXCEPT); writefpsr(new_r); return old_r & FE_ALL_EXCEPT; } int fegetexcept(void) { fenv_t r; r = readfpsr(); return r & FE_ALL_EXCEPT; }