/* $OpenBSD: fenv.c,v 1.8 2022/12/27 17:10:07 jmc Exp $ */ /* * Copyright (c) 2011 Martynas Venckus <martynas@openbsd.org> * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #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 = { 0x00000000, /* Control register */ 0x00000000 /* Status register */ }; /* * The feclearexcept() function clears the supported floating-point exceptions * represented by `excepts'. */ int feclearexcept(int excepts) { unsigned int fpsr; excepts &= FE_ALL_EXCEPT; /* Store the current floating-point status register */ __asm__ volatile ("fldcr %0, %%fcr62" : "=r" (fpsr)); /* Clear the requested floating-point exceptions */ fpsr &= ~excepts; /* Load the floating-point status register */ __asm__ volatile ("fstcr %0, %%fcr62" : : "r" (fpsr)); 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) { unsigned int fpsr; excepts &= FE_ALL_EXCEPT; /* Store the current floating-point status register */ __asm__ volatile ("fldcr %0, %%fcr62" : "=r" (fpsr)); /* Store the results in flagp */ *flagp = fpsr & excepts; return (0); } /* * The feraiseexcept() function raises the supported floating-point exceptions * represented by the argument `excepts'. */ 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 = 0x1p1023; d = 0x1p-1022 / d; } if (excepts & FE_INEXACT) { d = 0x1p-1022; d += 1.0; } return (0); } DEF_STD(feraiseexcept); /* * 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) { unsigned int fpsr; excepts &= FE_ALL_EXCEPT; /* Store the current floating-point status register */ __asm__ volatile ("fldcr %0, %%fcr62" : "=r" (fpsr)); /* Set the requested status flags */ fpsr &= ~excepts; fpsr |= *flagp & excepts; /* Load the floating-point status register */ __asm__ volatile ("fstcr %0, %%fcr62" : : "r" (fpsr)); return (0); } DEF_STD(fesetexceptflag); /* * 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) { unsigned int fpsr; excepts &= FE_ALL_EXCEPT; /* Store the current floating-point status register */ __asm__ volatile ("fldcr %0, %%fcr62" : "=r" (fpsr)); return (fpsr & excepts); } DEF_STD(fetestexcept); /* * The fegetround() function gets the current rounding direction. */ int fegetround(void) { unsigned int fpcr; /* Store the current floating-point control register */ __asm__ volatile ("fldcr %0, %%fcr63" : "=r" (fpcr)); return (fpcr & _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) { unsigned int fpcr; /* Check whether requested rounding direction is supported */ if (round & ~_ROUND_MASK) return (-1); /* Store the current floating-point control register */ __asm__ volatile ("fldcr %0, %%fcr63" : "=r" (fpcr)); /* Set the rounding direction */ fpcr &= ~_ROUND_MASK; fpcr |= round; /* Load the floating-point control register */ __asm__ volatile ("fstcr %0, %%fcr63" : : "r" (fpcr)); 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) { /* Store the current floating-point control and status registers */ __asm__ volatile ("fldcr %0, %%fcr63" : "=r" (envp->__control)); __asm__ volatile ("fldcr %0, %%fcr62" : "=r" (envp->__status)); 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) { unsigned int fpsr, fpcr; /* Store the current floating-point control and status registers */ __asm__ volatile ("fldcr %0, %%fcr63" : "=r" (envp->__control)); __asm__ volatile ("fldcr %0, %%fcr62" : "=r" (envp->__status)); /* Clear exception flags in FPSR */ fpsr = envp->__status; fpsr &= ~FE_ALL_EXCEPT; __asm__ volatile ("fstcr %0, %%fcr62" : : "r" (fpsr)); /* Mask all exceptions */ fpcr = envp->__control; fpcr &= ~FE_ALL_EXCEPT; __asm__ volatile ("fstcr %0, %%fcr63" : : "r" (fpcr)); 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) { fenv_t fenv; /* Store the current floating-point control and status registers */ __asm__ volatile ("fldcr %0, %%fcr63" : "=r" (fenv.__control)); __asm__ volatile ("fldcr %0, %%fcr62" : "=r" (fenv.__status)); /* Set the requested control flags */ fenv.__control &= ~(FE_ALL_EXCEPT | _ROUND_MASK); fenv.__control |= envp->__control & (FE_ALL_EXCEPT | _ROUND_MASK); /* Set the requested status flags */ fenv.__status &= ~FE_ALL_EXCEPT; fenv.__status |= envp->__status & FE_ALL_EXCEPT; /* Load the floating-point control and status registers */ __asm__ volatile ("fstcr %0, %%fcr63" : : "r" (fenv.__control)); __asm__ volatile ("fstcr %0, %%fcr62" : : "r" (fenv.__status)); 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) { unsigned int fpsr; /* Store the current floating-point status register */ __asm__ volatile ("fldcr %0, %%fcr62" : "=r" (fpsr)); /* Install new floating-point environment */ fesetenv(envp); /* Raise any previously accumulated exceptions */ feraiseexcept(fpsr); return (0); } DEF_STD(feupdateenv); /* * The following functions are extensions to the standard */ int feenableexcept(int mask) { unsigned int fpcr, omask; mask &= FE_ALL_EXCEPT; /* Store the current floating-point control register */ __asm__ volatile ("fldcr %0, %%fcr63" : "=r" (fpcr)); omask = fpcr & FE_ALL_EXCEPT; fpcr |= mask; /* Load the floating-point control register */ __asm__ volatile ("fstcr %0, %%fcr63" : : "r" (fpcr)); return (omask); } int fedisableexcept(int mask) { unsigned int fpcr, omask; mask &= FE_ALL_EXCEPT; /* Store the current floating-point control register */ __asm__ volatile ("fldcr %0, %%fcr63" : "=r" (fpcr)); omask = fpcr & FE_ALL_EXCEPT; fpcr &= ~mask; /* Load the floating-point control register */ __asm__ volatile ("fstcr %0, %%fcr63" : : "r" (fpcr)); return (omask); } int fegetexcept(void) { unsigned int fpcr; /* Store the current floating-point control register */ __asm__ volatile ("fldcr %0, %%fcr63" : "=r" (fpcr)); return (fpcr & FE_ALL_EXCEPT); }
