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fenv.c revision 1.6.12.1
      1  1.6.12.1    bouyer /* $NetBSD: fenv.c,v 1.6.12.1 2017/04/21 16:53:11 bouyer Exp $ */
      2       1.1     joerg 
      3       1.1     joerg /*-
      4       1.1     joerg  * Copyright (c) 2004-2005 David Schultz <das (at) FreeBSD.ORG>
      5       1.1     joerg  * All rights reserved.
      6       1.1     joerg  *
      7       1.1     joerg  * Redistribution and use in source and binary forms, with or without
      8       1.1     joerg  * modification, are permitted provided that the following conditions
      9       1.1     joerg  * are met:
     10       1.1     joerg  * 1. Redistributions of source code must retain the above copyright
     11       1.1     joerg  *    notice, this list of conditions and the following disclaimer.
     12       1.1     joerg  * 2. Redistributions in binary form must reproduce the above copyright
     13       1.1     joerg  *    notice, this list of conditions and the following disclaimer in the
     14       1.1     joerg  *    documentation and/or other materials provided with the distribution.
     15       1.1     joerg  *
     16       1.1     joerg  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     17       1.1     joerg  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     18       1.1     joerg  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     19       1.1     joerg  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     20       1.1     joerg  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     21       1.1     joerg  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     22       1.1     joerg  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     23       1.1     joerg  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     24       1.1     joerg  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     25       1.1     joerg  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26       1.1     joerg  * SUCH DAMAGE.
     27       1.1     joerg  */
     28       1.1     joerg 
     29       1.1     joerg #include <sys/cdefs.h>
     30  1.6.12.1    bouyer __RCSID("$NetBSD: fenv.c,v 1.6.12.1 2017/04/21 16:53:11 bouyer Exp $");
     31  1.6.12.1    bouyer 
     32  1.6.12.1    bouyer #include "namespace.h"
     33       1.1     joerg 
     34       1.1     joerg #include <assert.h>
     35       1.1     joerg #include <fenv.h>
     36       1.1     joerg #include <stddef.h>
     37       1.1     joerg #include <string.h>
     38       1.1     joerg 
     39  1.6.12.1    bouyer #ifdef __weak_alias
     40  1.6.12.1    bouyer __weak_alias(feclearexcept,_feclearexcept)
     41  1.6.12.1    bouyer __weak_alias(fedisableexcept,_fedisableexcept)
     42  1.6.12.1    bouyer __weak_alias(feenableexcept,_feenableexcept)
     43  1.6.12.1    bouyer __weak_alias(fegetenv,_fegetenv)
     44  1.6.12.1    bouyer __weak_alias(fegetexcept,_fegetexcept)
     45  1.6.12.1    bouyer __weak_alias(fegetexceptflag,_fegetexceptflag)
     46  1.6.12.1    bouyer __weak_alias(fegetround,_fegetround)
     47  1.6.12.1    bouyer __weak_alias(feholdexcept,_feholdexcept)
     48  1.6.12.1    bouyer __weak_alias(feraiseexcept,_feraiseexcept)
     49  1.6.12.1    bouyer __weak_alias(fesetenv,_fesetenv)
     50  1.6.12.1    bouyer __weak_alias(fesetexceptflag,_fesetexceptflag)
     51  1.6.12.1    bouyer __weak_alias(fesetround,_fesetround)
     52  1.6.12.1    bouyer __weak_alias(fetestexcept,_fetestexcept)
     53  1.6.12.1    bouyer __weak_alias(feupdateenv,_feupdateenv)
     54  1.6.12.1    bouyer #endif
     55  1.6.12.1    bouyer 
     56       1.1     joerg /* Load x87 Control Word */
     57       1.1     joerg #define	__fldcw(__cw)		__asm__ __volatile__ \
     58       1.1     joerg 	("fldcw %0" : : "m" (__cw))
     59       1.1     joerg 
     60       1.1     joerg /* No-Wait Store Control Word */
     61       1.1     joerg #define	__fnstcw(__cw)		__asm__ __volatile__ \
     62       1.1     joerg 	("fnstcw %0" : "=m" (*(__cw)))
     63       1.1     joerg 
     64       1.1     joerg /* No-Wait Store Status Word */
     65       1.1     joerg #define	__fnstsw(__sw)		__asm__ __volatile__ \
     66       1.1     joerg 	("fnstsw %0" : "=am" (*(__sw)))
     67       1.1     joerg 
     68       1.1     joerg /* No-Wait Clear Exception Flags */
     69       1.1     joerg #define	__fnclex()		__asm__ __volatile__ \
     70       1.1     joerg 	("fnclex")
     71       1.1     joerg 
     72       1.1     joerg /* Load x87 Environment */
     73       1.1     joerg #define	__fldenv(__env)		__asm__ __volatile__ \
     74       1.1     joerg 	("fldenv %0" : : "m" (__env))
     75       1.1     joerg 
     76       1.1     joerg /* No-Wait Store x87 environment */
     77       1.1     joerg #define	__fnstenv(__env)	__asm__ __volatile__ \
     78       1.1     joerg 	("fnstenv %0" : "=m" (*(__env)))
     79       1.1     joerg 
     80       1.4  riastrad /* Check for and handle pending unmasked x87 pending FPU exceptions */
     81       1.4  riastrad #define	__fwait(__env)		__asm__	__volatile__	\
     82       1.4  riastrad 	("fwait")
     83       1.4  riastrad 
     84       1.1     joerg /* Load the MXCSR register */
     85       1.1     joerg #define	__ldmxcsr(__mxcsr)	__asm__ __volatile__ \
     86       1.1     joerg 	("ldmxcsr %0" : : "m" (__mxcsr))
     87       1.1     joerg 
     88       1.1     joerg /* Store the MXCSR register state */
     89       1.1     joerg #define	__stmxcsr(__mxcsr)	__asm__ __volatile__ \
     90       1.1     joerg 	("stmxcsr %0" : "=m" (*(__mxcsr)))
     91       1.1     joerg 
     92       1.1     joerg /*
     93       1.1     joerg  * The following constant represents the default floating-point environment
     94       1.1     joerg  * (that is, the one installed at program startup) and has type pointer to
     95       1.1     joerg  * const-qualified fenv_t.
     96       1.1     joerg  *
     97       1.1     joerg  * It can be used as an argument to the functions within the <fenv.h> header
     98       1.1     joerg  * that manage the floating-point environment, namely fesetenv() and
     99       1.1     joerg  * feupdateenv().
    100       1.1     joerg  *
    101       1.1     joerg  * x87 fpu registers are 16bit wide. The upper bits, 31-16, are marked as
    102       1.1     joerg  * RESERVED. We provide a partial floating-point environment, where we
    103       1.1     joerg  * define only the lower bits. The reserved bits are extracted and set by
    104       1.1     joerg  * the consumers of FE_DFL_ENV, during runtime.
    105       1.1     joerg  */
    106       1.1     joerg fenv_t __fe_dfl_env = {
    107       1.1     joerg 	{
    108       1.1     joerg 		__NetBSD_NPXCW__,	/* Control word register */
    109       1.1     joerg 		0x00000000,		/* Status word register */
    110       1.1     joerg 		0x0000ffff,		/* Tag word register */
    111       1.1     joerg 		{
    112       1.1     joerg 			0x00000000,
    113       1.1     joerg 			0x00000000,
    114       1.1     joerg 			0x00000000,
    115       1.1     joerg 			0x00000000,
    116       1.1     joerg 		},
    117       1.1     joerg 	},
    118       1.1     joerg 	__INITIAL_MXCSR__       /* MXCSR register */
    119       1.1     joerg };
    120       1.1     joerg #define FE_DFL_ENV      ((const fenv_t *) &__fe_dfl_env)
    121       1.1     joerg 
    122       1.6     joerg static void __init_libm(void) __attribute__ ((constructor, used));
    123       1.6     joerg 
    124       1.6     joerg static void __init_libm(void)
    125       1.6     joerg {
    126       1.6     joerg 	uint16_t control;
    127       1.6     joerg 
    128       1.6     joerg 	__fnstcw(&control);
    129       1.6     joerg 	__fe_dfl_env.x87.control = control;
    130       1.6     joerg }
    131       1.6     joerg 
    132       1.1     joerg 
    133       1.1     joerg /*
    134       1.1     joerg  * The feclearexcept() function clears the supported floating-point exceptions
    135       1.1     joerg  * represented by `excepts'.
    136       1.1     joerg  */
    137       1.1     joerg int
    138       1.1     joerg feclearexcept(int excepts)
    139       1.1     joerg {
    140       1.1     joerg 	fenv_t fenv;
    141       1.1     joerg 	int ex;
    142       1.1     joerg 
    143       1.1     joerg 	_DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
    144       1.1     joerg 
    145       1.1     joerg 	ex = excepts & FE_ALL_EXCEPT;
    146       1.1     joerg 
    147       1.1     joerg 	/* Store the current x87 floating-point environment */
    148       1.1     joerg 	__fnstenv(&fenv);
    149       1.1     joerg 
    150       1.1     joerg 	/* Clear the requested floating-point exceptions */
    151       1.1     joerg 	fenv.x87.status &= ~ex;
    152       1.1     joerg 
    153       1.1     joerg 	/* Load the x87 floating-point environent */
    154       1.1     joerg 	__fldenv(fenv);
    155       1.1     joerg 
    156       1.1     joerg 	/* Same for SSE environment */
    157       1.1     joerg 	__stmxcsr(&fenv.mxcsr);
    158       1.1     joerg 	fenv.mxcsr &= ~ex;
    159       1.1     joerg 	__ldmxcsr(fenv.mxcsr);
    160       1.1     joerg 
    161       1.1     joerg 	/* Success */
    162       1.1     joerg 	return (0);
    163       1.1     joerg }
    164       1.1     joerg 
    165       1.1     joerg /*
    166       1.1     joerg  * The fegetexceptflag() function stores an implementation-defined
    167       1.1     joerg  * representation of the states of the floating-point status flags indicated by
    168       1.1     joerg  * the argument excepts in the object pointed to by the argument flagp.
    169       1.1     joerg  */
    170       1.1     joerg int
    171       1.1     joerg fegetexceptflag(fexcept_t *flagp, int excepts)
    172       1.1     joerg {
    173       1.1     joerg 	uint32_t mxcsr;
    174       1.1     joerg 	uint16_t x87_status;
    175       1.1     joerg 	int ex;
    176       1.1     joerg 
    177       1.1     joerg 	_DIAGASSERT(flagp != NULL);
    178       1.1     joerg 	_DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
    179       1.1     joerg 
    180       1.1     joerg 	ex = excepts & FE_ALL_EXCEPT;
    181       1.1     joerg 
    182       1.1     joerg 	/* Store the current x87 status register */
    183       1.1     joerg 	__fnstsw(&x87_status);
    184       1.1     joerg 
    185       1.1     joerg 	/* Store the MXCSR register */
    186       1.1     joerg 	__stmxcsr(&mxcsr);
    187       1.1     joerg 
    188       1.1     joerg 	/* Store the results in flagp */
    189       1.1     joerg 	*flagp = (x87_status | mxcsr) & ex;
    190       1.1     joerg 
    191       1.1     joerg 	/* Success */
    192       1.1     joerg 	return (0);
    193       1.1     joerg }
    194       1.1     joerg 
    195       1.1     joerg /*
    196       1.1     joerg  * The feraiseexcept() function raises the supported floating-point exceptions
    197       1.1     joerg  * represented by the argument `excepts'.
    198       1.1     joerg  *
    199       1.1     joerg  * The standard explicitly allows us to execute an instruction that has the
    200       1.1     joerg  * exception as a side effect, but we choose to manipulate the status register
    201       1.1     joerg  * directly.
    202       1.1     joerg  *
    203       1.1     joerg  * The validation of input is being deferred to fesetexceptflag().
    204       1.1     joerg  */
    205       1.1     joerg int
    206       1.1     joerg feraiseexcept(int excepts)
    207       1.1     joerg {
    208       1.1     joerg 	int ex;
    209       1.1     joerg 
    210       1.1     joerg 	_DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
    211       1.1     joerg 
    212       1.1     joerg 	ex = excepts & FE_ALL_EXCEPT;
    213       1.5  christos 	fesetexceptflag((unsigned int *)&ex, ex);
    214       1.4  riastrad 	__fwait();
    215       1.1     joerg 
    216       1.1     joerg 	/* Success */
    217       1.1     joerg 	return (0);
    218       1.1     joerg }
    219       1.1     joerg 
    220       1.1     joerg /*
    221       1.1     joerg  * This function sets the floating-point status flags indicated by the argument
    222       1.1     joerg  * `excepts' to the states stored in the object pointed to by `flagp'. It does
    223       1.1     joerg  * NOT raise any floating-point exceptions, but only sets the state of the flags.
    224       1.1     joerg  */
    225       1.1     joerg int
    226       1.1     joerg fesetexceptflag(const fexcept_t *flagp, int excepts)
    227       1.1     joerg {
    228       1.1     joerg 	fenv_t fenv;
    229       1.1     joerg 	int ex;
    230       1.1     joerg 
    231       1.1     joerg 	_DIAGASSERT(flagp != NULL);
    232       1.1     joerg 	_DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
    233       1.1     joerg 
    234       1.1     joerg 	ex = excepts & FE_ALL_EXCEPT;
    235       1.1     joerg 
    236       1.1     joerg 	/* Store the current x87 floating-point environment */
    237       1.1     joerg 	__fnstenv(&fenv);
    238       1.1     joerg 
    239       1.1     joerg 	/* Set the requested status flags */
    240       1.1     joerg 	fenv.x87.status |= *flagp & ex;
    241       1.1     joerg 
    242       1.1     joerg 	/* Load the x87 floating-point environent */
    243       1.1     joerg 	__fldenv(fenv);
    244       1.1     joerg 
    245       1.1     joerg 	/* Same for SSE environment */
    246       1.1     joerg 	__stmxcsr(&fenv.mxcsr);
    247       1.1     joerg 	fenv.mxcsr |= *flagp & ex;
    248       1.1     joerg 	__ldmxcsr(fenv.mxcsr);
    249       1.1     joerg 
    250       1.1     joerg 	/* Success */
    251       1.1     joerg 	return (0);
    252       1.1     joerg }
    253       1.1     joerg 
    254       1.1     joerg /*
    255       1.1     joerg  * The fetestexcept() function determines which of a specified subset of the
    256       1.1     joerg  * floating-point exception flags are currently set. The `excepts' argument
    257       1.1     joerg  * specifies the floating-point status flags to be queried.
    258       1.1     joerg  */
    259       1.1     joerg int
    260       1.1     joerg fetestexcept(int excepts)
    261       1.1     joerg {
    262       1.1     joerg 	fenv_t fenv;
    263       1.1     joerg 	uint32_t mxcsr;
    264       1.1     joerg 	uint16_t status;
    265       1.1     joerg 	int ex;
    266       1.1     joerg 
    267       1.1     joerg 	_DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
    268       1.1     joerg 
    269       1.1     joerg 	ex = excepts & FE_ALL_EXCEPT;
    270       1.1     joerg 
    271       1.1     joerg 	/* Store the current x87 floating-point environment */
    272       1.1     joerg 	memset(&fenv, 0, sizeof(fenv));
    273       1.1     joerg 
    274       1.1     joerg 	__fnstenv(&fenv);
    275       1.1     joerg 	__fnstsw(&status);
    276       1.1     joerg 
    277       1.1     joerg 	/* Store the MXCSR register state */
    278       1.1     joerg 	__stmxcsr(&fenv.mxcsr);
    279       1.1     joerg 	__stmxcsr(&mxcsr);
    280       1.1     joerg 
    281       1.1     joerg 	return ((fenv.x87.status | fenv.mxcsr) & ex);
    282       1.1     joerg }
    283       1.1     joerg 
    284       1.1     joerg /*
    285       1.1     joerg  * The fegetround() function gets the current rounding direction.
    286       1.1     joerg  */
    287       1.1     joerg int
    288       1.1     joerg fegetround(void)
    289       1.1     joerg {
    290       1.1     joerg 	uint32_t mxcsr;
    291       1.1     joerg 	uint16_t control;
    292       1.1     joerg 
    293       1.1     joerg 	/*
    294       1.1     joerg 	 * We check both the x87 floating-point unit _and_ the SSE unit.
    295       1.1     joerg 	 * Normally, those two must agree with respect to each other. If they
    296       1.1     joerg 	 * don't, it's not our fault and the result is non-determinable, in
    297       1.1     joerg 	 * which case POSIX says that a negative value should be returned.
    298       1.1     joerg 	 */
    299       1.1     joerg 	__fnstcw(&control);
    300       1.1     joerg 	__stmxcsr(&mxcsr);
    301       1.1     joerg 
    302       1.1     joerg 	if ((control & _X87_ROUNDING_MASK)
    303       1.1     joerg 	    != ((mxcsr & _SSE_ROUNDING_MASK) >> 3)) {
    304       1.1     joerg 		return (-1);
    305       1.1     joerg 	}
    306       1.1     joerg 
    307       1.1     joerg 	return (control & _X87_ROUNDING_MASK);
    308       1.1     joerg }
    309       1.1     joerg 
    310       1.1     joerg /*
    311       1.1     joerg  * The fesetround() function establishes the rounding direction represented by
    312       1.1     joerg  * its argument `round'. If the argument is not equal to the value of a rounding
    313       1.1     joerg  * direction macro, the rounding direction is not changed.
    314       1.1     joerg  */
    315       1.1     joerg int
    316       1.1     joerg fesetround(int round)
    317       1.1     joerg {
    318       1.1     joerg 	uint32_t  mxcsr;
    319       1.1     joerg 	uint16_t control;
    320       1.1     joerg 
    321       1.1     joerg 	/* Check whether requested rounding direction is supported */
    322       1.1     joerg 	if (round & (~_X87_ROUNDING_MASK))
    323       1.1     joerg 		return (-1);
    324       1.1     joerg 
    325       1.1     joerg 	/* Store the current x87 control word register  */
    326       1.1     joerg 	__fnstcw(&control);
    327       1.1     joerg 
    328       1.1     joerg 	/*
    329       1.1     joerg 	 * Set the rounding direction
    330       1.1     joerg 	 * Rounding Control is bits 10-11, so shift appropriately
    331       1.1     joerg 	 */
    332       1.1     joerg 	control &= ~_X87_ROUNDING_MASK;
    333       1.1     joerg 	control |= round;
    334       1.1     joerg 
    335       1.1     joerg 	/* Load the x87 control word register */
    336       1.1     joerg 	__fldcw(control);
    337       1.1     joerg 
    338       1.1     joerg 	/*
    339       1.1     joerg 	 * Same for the SSE environment
    340       1.1     joerg 	 * Rounding Control is bits 13-14, so shift appropriately
    341       1.1     joerg 	 */
    342       1.1     joerg 	__stmxcsr(&mxcsr);
    343       1.1     joerg 	mxcsr &= ~_SSE_ROUNDING_MASK;
    344       1.1     joerg 	mxcsr |= (round << _SSE_ROUND_SHIFT);
    345       1.1     joerg 	__ldmxcsr(mxcsr);
    346       1.1     joerg 
    347       1.1     joerg 	/* Success */
    348       1.1     joerg 	return (0);
    349       1.1     joerg }
    350       1.1     joerg 
    351       1.1     joerg /*
    352       1.1     joerg  * The fegetenv() function attempts to store the current floating-point
    353       1.1     joerg  * environment in the object pointed to by envp.
    354       1.1     joerg  */
    355       1.1     joerg int
    356       1.1     joerg fegetenv(fenv_t *envp)
    357       1.1     joerg {
    358       1.1     joerg 	_DIAGASSERT(envp != NULL);
    359       1.1     joerg 
    360       1.1     joerg 	/* Store the current x87 floating-point environment */
    361       1.1     joerg 	__fnstenv(envp);
    362       1.1     joerg 
    363       1.1     joerg 	/* Store the MXCSR register state */
    364       1.1     joerg 	__stmxcsr(&envp->mxcsr);
    365       1.1     joerg 
    366       1.1     joerg      /*
    367       1.1     joerg       * When an FNSTENV instruction is executed, all pending exceptions are
    368       1.1     joerg       * essentially lost (either the x87 FPU status register is cleared or all
    369       1.1     joerg       * exceptions are masked).
    370       1.1     joerg       *
    371       1.1     joerg       * 8.6 X87 FPU EXCEPTION SYNCHRONIZATION -
    372       1.1     joerg       * Intel(R) 64 and IA-32 Architectures Softare Developer's Manual - Vol 1
    373       1.1     joerg       *
    374       1.1     joerg       */
    375       1.1     joerg 	__fldcw(envp->x87.control);
    376       1.1     joerg 
    377       1.1     joerg 	/* Success */
    378       1.1     joerg 	return (0);
    379       1.1     joerg }
    380       1.1     joerg 
    381       1.1     joerg /*
    382       1.1     joerg  * The feholdexcept() function saves the current floating-point environment
    383       1.1     joerg  * in the object pointed to by envp, clears the floating-point status flags, and
    384       1.1     joerg  * then installs a non-stop (continue on floating-point exceptions) mode, if
    385       1.1     joerg  * available, for all floating-point exceptions.
    386       1.1     joerg  */
    387       1.1     joerg int
    388       1.1     joerg feholdexcept(fenv_t *envp)
    389       1.1     joerg {
    390       1.1     joerg 	uint32_t mxcsr;
    391       1.1     joerg 
    392       1.1     joerg 	_DIAGASSERT(envp != NULL);
    393       1.1     joerg 
    394       1.1     joerg 	/* Store the current x87 floating-point environment */
    395       1.1     joerg 	__fnstenv(envp);
    396       1.1     joerg 
    397       1.1     joerg 	/* Clear all exception flags in FPU */
    398       1.1     joerg 	__fnclex();
    399       1.1     joerg 
    400       1.1     joerg 	/* Store the MXCSR register state */
    401       1.1     joerg 	__stmxcsr(&envp->mxcsr);
    402       1.1     joerg 
    403       1.1     joerg 	/* Clear exception flags in MXCSR XXX */
    404       1.1     joerg 	mxcsr = envp->mxcsr;
    405       1.1     joerg 	mxcsr &= ~FE_ALL_EXCEPT;
    406       1.1     joerg 
    407       1.1     joerg 	/* Mask all exceptions */
    408       1.1     joerg 	mxcsr |= FE_ALL_EXCEPT << _SSE_EMASK_SHIFT;
    409       1.1     joerg 
    410       1.1     joerg 	__ldmxcsr(mxcsr);
    411       1.1     joerg 
    412       1.1     joerg 	/* Success */
    413       1.1     joerg 	return (0);
    414       1.1     joerg }
    415       1.1     joerg 
    416       1.1     joerg /*
    417       1.1     joerg  * The fesetenv() function attempts to establish the floating-point environment
    418       1.1     joerg  * represented by the object pointed to by envp. The argument `envp' points
    419       1.1     joerg  * to an object set by a call to fegetenv() or feholdexcept(), or equal a
    420       1.1     joerg  * floating-point environment macro. The fesetenv() function does not raise
    421       1.1     joerg  * floating-point exceptions, but only installs the state of the floating-point
    422       1.1     joerg  * status flags represented through its argument.
    423       1.1     joerg  */
    424       1.1     joerg int
    425       1.1     joerg fesetenv(const fenv_t *envp)
    426       1.1     joerg {
    427       1.1     joerg 	fenv_t fenv;
    428       1.1     joerg 
    429       1.1     joerg 	_DIAGASSERT(envp != NULL);
    430       1.1     joerg 
    431       1.1     joerg 	/* Store the x87 floating-point environment */
    432       1.1     joerg 	memset(&fenv, 0, sizeof fenv);
    433       1.1     joerg 	__fnstenv(&fenv);
    434       1.1     joerg 
    435       1.1     joerg 	__fe_dfl_env.x87.control = (fenv.x87.control & 0xffff0000)
    436       1.1     joerg 	    | (__fe_dfl_env.x87.control & 0x0000ffff);
    437       1.1     joerg 	__fe_dfl_env.x87.status = (fenv.x87.status & 0xffff0000)
    438       1.1     joerg 	    | (__fe_dfl_env.x87.status & 0x0000ffff);
    439       1.1     joerg 	__fe_dfl_env.x87.tag = (fenv.x87.tag & 0xffff0000)
    440       1.1     joerg 	    | (__fe_dfl_env.x87.tag & 0x0000ffff);
    441       1.1     joerg 	__fe_dfl_env.x87.others[3] = (fenv.x87.others[3] & 0xffff0000)
    442       1.1     joerg 	    | (__fe_dfl_env.x87.others[3] & 0x0000ffff);
    443       1.1     joerg 	__fldenv(*envp);
    444       1.1     joerg 
    445       1.1     joerg 	/* Store the MXCSR register */
    446       1.1     joerg 	__ldmxcsr(envp->mxcsr);
    447       1.1     joerg 
    448       1.1     joerg 	/* Success */
    449       1.1     joerg 	return (0);
    450       1.1     joerg }
    451       1.1     joerg 
    452       1.1     joerg /*
    453       1.1     joerg  * The feupdateenv() function saves the currently raised floating-point
    454       1.1     joerg  * exceptions in its automatic storage, installs the floating-point environment
    455       1.1     joerg  * represented by the object pointed to by `envp', and then raises the saved
    456       1.1     joerg  * floating-point exceptions. The argument `envp' shall point to an object set
    457       1.1     joerg  * by a call to feholdexcept() or fegetenv(), or equal a floating-point
    458       1.1     joerg  * environment macro.
    459       1.1     joerg  */
    460       1.1     joerg int
    461       1.1     joerg feupdateenv(const fenv_t *envp)
    462       1.1     joerg {
    463       1.1     joerg 	fenv_t fenv;
    464       1.1     joerg 	uint32_t mxcsr;
    465       1.1     joerg 	uint16_t sw;
    466       1.1     joerg 
    467       1.1     joerg 	_DIAGASSERT(envp != NULL);
    468       1.1     joerg 
    469       1.1     joerg 	/* Store the x87 floating-point environment */
    470       1.1     joerg 	memset(&fenv, 0, sizeof(fenv));
    471       1.1     joerg 	__fnstenv(&fenv);
    472       1.1     joerg 
    473       1.1     joerg 	__fe_dfl_env.x87.control = (fenv.x87.control & 0xffff0000)
    474       1.1     joerg 	    | (__fe_dfl_env.x87.control & 0x0000ffff);
    475       1.1     joerg 	__fe_dfl_env.x87.status = (fenv.x87.status & 0xffff0000)
    476       1.1     joerg 	    | (__fe_dfl_env.x87.status & 0x0000ffff);
    477       1.1     joerg 	__fe_dfl_env.x87.tag = (fenv.x87.tag & 0xffff0000)
    478       1.1     joerg 	    | (__fe_dfl_env.x87.tag & 0x0000ffff);
    479       1.1     joerg 	__fe_dfl_env.x87.others[3] = (fenv.x87.others[3] & 0xffff0000)
    480       1.1     joerg 	    | (__fe_dfl_env.x87.others[3] & 0x0000ffff);
    481       1.1     joerg 
    482       1.1     joerg 	/* Store the x87 status register */
    483       1.1     joerg 	__fnstsw(&sw);
    484       1.1     joerg 
    485       1.1     joerg 	/* Store the MXCSR register */
    486       1.1     joerg 	__stmxcsr(&mxcsr);
    487       1.1     joerg 
    488       1.1     joerg 	/* Install new floating-point environment */
    489       1.1     joerg 	fesetenv(envp);
    490       1.1     joerg 
    491       1.1     joerg 	/* Raise any previously accumulated exceptions */
    492       1.1     joerg 	feraiseexcept((sw | mxcsr) & FE_ALL_EXCEPT);
    493       1.1     joerg 
    494       1.1     joerg 	/* Success */
    495       1.1     joerg 	return (0);
    496       1.1     joerg }
    497       1.1     joerg 
    498       1.1     joerg /*
    499       1.1     joerg  * The following functions are extentions to the standard
    500       1.1     joerg  */
    501       1.1     joerg int
    502       1.1     joerg feenableexcept(int mask)
    503       1.1     joerg {
    504       1.1     joerg 	uint32_t mxcsr, omask;
    505       1.1     joerg 	uint16_t control;
    506       1.1     joerg 
    507       1.1     joerg 	_DIAGASSERT((mask & ~FE_ALL_EXCEPT) == 0);
    508       1.1     joerg 	mask &= FE_ALL_EXCEPT;
    509       1.1     joerg 
    510       1.1     joerg 	__fnstcw(&control);
    511       1.1     joerg 	__stmxcsr(&mxcsr);
    512       1.1     joerg 
    513       1.1     joerg 	omask = (control | mxcsr >> _SSE_EMASK_SHIFT) & FE_ALL_EXCEPT;
    514       1.1     joerg 	control &= ~mask;
    515       1.1     joerg 	__fldcw(control);
    516       1.1     joerg 
    517       1.1     joerg 	mxcsr &= ~(mask << _SSE_EMASK_SHIFT);
    518       1.1     joerg 	__ldmxcsr(mxcsr);
    519       1.1     joerg 
    520       1.2  riastrad 	return (FE_ALL_EXCEPT & ~omask);
    521       1.1     joerg 
    522       1.1     joerg }
    523       1.1     joerg 
    524       1.1     joerg int
    525       1.1     joerg fedisableexcept(int mask)
    526       1.1     joerg {
    527       1.1     joerg 	uint32_t mxcsr, omask;
    528       1.1     joerg 	uint16_t control;
    529       1.1     joerg 
    530       1.1     joerg 	_DIAGASSERT((mask & ~FE_ALL_EXCEPT) == 0);
    531       1.1     joerg 
    532       1.1     joerg 	__fnstcw(&control);
    533       1.1     joerg 	__stmxcsr(&mxcsr);
    534       1.1     joerg 
    535       1.1     joerg 	omask = (control | mxcsr >> _SSE_EMASK_SHIFT) & FE_ALL_EXCEPT;
    536       1.1     joerg 	control |= mask;
    537       1.1     joerg 	__fldcw(control);
    538       1.1     joerg 
    539       1.1     joerg 	mxcsr |= mask << _SSE_EMASK_SHIFT;
    540       1.1     joerg 	__ldmxcsr(mxcsr);
    541       1.1     joerg 
    542       1.2  riastrad 	return (FE_ALL_EXCEPT & ~omask);
    543       1.1     joerg }
    544       1.1     joerg 
    545       1.1     joerg int
    546       1.1     joerg fegetexcept(void)
    547       1.1     joerg {
    548       1.1     joerg 	uint16_t control;
    549       1.1     joerg 
    550       1.1     joerg 	/*
    551       1.1     joerg 	 * We assume that the masks for the x87 and the SSE unit are
    552       1.1     joerg 	 * the same.
    553       1.1     joerg 	 */
    554       1.1     joerg 	__fnstcw(&control);
    555       1.1     joerg 
    556       1.3  riastrad 	return (~control & FE_ALL_EXCEPT);
    557       1.1     joerg }
    558       1.1     joerg 
    559