525 lines
13 KiB
C
525 lines
13 KiB
C
|
/* $NetBSD: fenv.c,v 1.1 2010/07/31 21:47:53 joerg Exp $ */
|
||
|
|
||
|
/*-
|
||
|
* Copyright (c) 2004-2005 David Schultz <das (at) 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
|
||
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
||
|
* SUCH DAMAGE.
|
||
|
*/
|
||
|
|
||
|
#include <sys/cdefs.h>
|
||
|
__RCSID("$NetBSD: fenv.c,v 1.1 2010/07/31 21:47:53 joerg Exp $");
|
||
|
|
||
|
#include <assert.h>
|
||
|
#include <fenv.h>
|
||
|
#include <stddef.h>
|
||
|
#include <string.h>
|
||
|
|
||
|
/* Load x87 Control Word */
|
||
|
#define __fldcw(__cw) __asm__ __volatile__ \
|
||
|
("fldcw %0" : : "m" (__cw))
|
||
|
|
||
|
/* No-Wait Store Control Word */
|
||
|
#define __fnstcw(__cw) __asm__ __volatile__ \
|
||
|
("fnstcw %0" : "=m" (*(__cw)))
|
||
|
|
||
|
/* No-Wait Store Status Word */
|
||
|
#define __fnstsw(__sw) __asm__ __volatile__ \
|
||
|
("fnstsw %0" : "=am" (*(__sw)))
|
||
|
|
||
|
/* No-Wait Clear Exception Flags */
|
||
|
#define __fnclex() __asm__ __volatile__ \
|
||
|
("fnclex")
|
||
|
|
||
|
/* Load x87 Environment */
|
||
|
#define __fldenv(__env) __asm__ __volatile__ \
|
||
|
("fldenv %0" : : "m" (__env))
|
||
|
|
||
|
/* No-Wait Store x87 environment */
|
||
|
#define __fnstenv(__env) __asm__ __volatile__ \
|
||
|
("fnstenv %0" : "=m" (*(__env)))
|
||
|
|
||
|
/* Load the MXCSR register */
|
||
|
#define __ldmxcsr(__mxcsr) __asm__ __volatile__ \
|
||
|
("ldmxcsr %0" : : "m" (__mxcsr))
|
||
|
|
||
|
/* Store the MXCSR register state */
|
||
|
#define __stmxcsr(__mxcsr) __asm__ __volatile__ \
|
||
|
("stmxcsr %0" : "=m" (*(__mxcsr)))
|
||
|
|
||
|
/*
|
||
|
* 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().
|
||
|
*
|
||
|
* x87 fpu registers are 16bit wide. The upper bits, 31-16, are marked as
|
||
|
* RESERVED. We provide a partial floating-point environment, where we
|
||
|
* define only the lower bits. The reserved bits are extracted and set by
|
||
|
* the consumers of FE_DFL_ENV, during runtime.
|
||
|
*/
|
||
|
fenv_t __fe_dfl_env = {
|
||
|
{
|
||
|
__NetBSD_NPXCW__, /* Control word register */
|
||
|
0x00000000, /* Status word register */
|
||
|
0x0000ffff, /* Tag word register */
|
||
|
{
|
||
|
0x00000000,
|
||
|
0x00000000,
|
||
|
0x00000000,
|
||
|
0x00000000,
|
||
|
},
|
||
|
},
|
||
|
__INITIAL_MXCSR__ /* MXCSR register */
|
||
|
};
|
||
|
#define FE_DFL_ENV ((const fenv_t *) &__fe_dfl_env)
|
||
|
|
||
|
|
||
|
/*
|
||
|
* The feclearexcept() function clears the supported floating-point exceptions
|
||
|
* represented by `excepts'.
|
||
|
*/
|
||
|
int
|
||
|
feclearexcept(int excepts)
|
||
|
{
|
||
|
fenv_t fenv;
|
||
|
int ex;
|
||
|
|
||
|
_DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
|
||
|
|
||
|
ex = excepts & FE_ALL_EXCEPT;
|
||
|
|
||
|
/* Store the current x87 floating-point environment */
|
||
|
__fnstenv(&fenv);
|
||
|
|
||
|
/* Clear the requested floating-point exceptions */
|
||
|
fenv.x87.status &= ~ex;
|
||
|
|
||
|
/* Load the x87 floating-point environent */
|
||
|
__fldenv(fenv);
|
||
|
|
||
|
/* Same for SSE environment */
|
||
|
__stmxcsr(&fenv.mxcsr);
|
||
|
fenv.mxcsr &= ~ex;
|
||
|
__ldmxcsr(fenv.mxcsr);
|
||
|
|
||
|
/* 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)
|
||
|
{
|
||
|
uint32_t mxcsr;
|
||
|
uint16_t x87_status;
|
||
|
int ex;
|
||
|
|
||
|
_DIAGASSERT(flagp != NULL);
|
||
|
_DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
|
||
|
|
||
|
ex = excepts & FE_ALL_EXCEPT;
|
||
|
|
||
|
/* Store the current x87 status register */
|
||
|
__fnstsw(&x87_status);
|
||
|
|
||
|
/* Store the MXCSR register */
|
||
|
__stmxcsr(&mxcsr);
|
||
|
|
||
|
/* Store the results in flagp */
|
||
|
*flagp = (x87_status | mxcsr) & ex;
|
||
|
|
||
|
/* Success */
|
||
|
return (0);
|
||
|
}
|
||
|
|
||
|
/*
|
||
|
* The feraiseexcept() function raises the supported floating-point exceptions
|
||
|
* represented by the argument `excepts'.
|
||
|
*
|
||
|
* The standard explicitly allows us to execute an instruction that has the
|
||
|
* exception as a side effect, but we choose to manipulate the status register
|
||
|
* directly.
|
||
|
*
|
||
|
* The validation of input is being deferred to fesetexceptflag().
|
||
|
*/
|
||
|
int
|
||
|
feraiseexcept(int excepts)
|
||
|
{
|
||
|
int ex;
|
||
|
|
||
|
_DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
|
||
|
|
||
|
ex = excepts & FE_ALL_EXCEPT;
|
||
|
fesetexceptflag((unsigned int *)&excepts, excepts);
|
||
|
|
||
|
/* 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)
|
||
|
{
|
||
|
fenv_t fenv;
|
||
|
int ex;
|
||
|
|
||
|
_DIAGASSERT(flagp != NULL);
|
||
|
_DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
|
||
|
|
||
|
ex = excepts & FE_ALL_EXCEPT;
|
||
|
|
||
|
/* Store the current x87 floating-point environment */
|
||
|
__fnstenv(&fenv);
|
||
|
|
||
|
/* Set the requested status flags */
|
||
|
fenv.x87.status |= *flagp & ex;
|
||
|
|
||
|
/* Load the x87 floating-point environent */
|
||
|
__fldenv(fenv);
|
||
|
|
||
|
/* Same for SSE environment */
|
||
|
__stmxcsr(&fenv.mxcsr);
|
||
|
fenv.mxcsr |= *flagp & ex;
|
||
|
__ldmxcsr(fenv.mxcsr);
|
||
|
|
||
|
/* 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)
|
||
|
{
|
||
|
fenv_t fenv;
|
||
|
uint32_t mxcsr;
|
||
|
uint16_t status;
|
||
|
int ex;
|
||
|
|
||
|
_DIAGASSERT((excepts & ~FE_ALL_EXCEPT) == 0);
|
||
|
|
||
|
ex = excepts & FE_ALL_EXCEPT;
|
||
|
|
||
|
/* Store the current x87 floating-point environment */
|
||
|
memset(&fenv, 0, sizeof(fenv));
|
||
|
|
||
|
__fnstenv(&fenv);
|
||
|
__fnstsw(&status);
|
||
|
|
||
|
/* Store the MXCSR register state */
|
||
|
__stmxcsr(&fenv.mxcsr);
|
||
|
__stmxcsr(&mxcsr);
|
||
|
|
||
|
return ((fenv.x87.status | fenv.mxcsr) & ex);
|
||
|
}
|
||
|
|
||
|
/*
|
||
|
* The fegetround() function gets the current rounding direction.
|
||
|
*/
|
||
|
int
|
||
|
fegetround(void)
|
||
|
{
|
||
|
uint32_t mxcsr;
|
||
|
uint16_t control;
|
||
|
|
||
|
/*
|
||
|
* We check both the x87 floating-point unit _and_ the SSE unit.
|
||
|
* Normally, those two must agree with respect to each other. If they
|
||
|
* don't, it's not our fault and the result is non-determinable, in
|
||
|
* which case POSIX says that a negative value should be returned.
|
||
|
*/
|
||
|
__fnstcw(&control);
|
||
|
__stmxcsr(&mxcsr);
|
||
|
|
||
|
if ((control & _X87_ROUNDING_MASK)
|
||
|
!= ((mxcsr & _SSE_ROUNDING_MASK) >> 3)) {
|
||
|
return (-1);
|
||
|
}
|
||
|
|
||
|
return (control & _X87_ROUNDING_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)
|
||
|
{
|
||
|
uint32_t mxcsr;
|
||
|
uint16_t control;
|
||
|
|
||
|
/* Check whether requested rounding direction is supported */
|
||
|
if (round & (~_X87_ROUNDING_MASK))
|
||
|
return (-1);
|
||
|
|
||
|
/* Store the current x87 control word register */
|
||
|
__fnstcw(&control);
|
||
|
|
||
|
/*
|
||
|
* Set the rounding direction
|
||
|
* Rounding Control is bits 10-11, so shift appropriately
|
||
|
*/
|
||
|
control &= ~_X87_ROUNDING_MASK;
|
||
|
control |= round;
|
||
|
|
||
|
/* Load the x87 control word register */
|
||
|
__fldcw(control);
|
||
|
|
||
|
/*
|
||
|
* Same for the SSE environment
|
||
|
* Rounding Control is bits 13-14, so shift appropriately
|
||
|
*/
|
||
|
__stmxcsr(&mxcsr);
|
||
|
mxcsr &= ~_SSE_ROUNDING_MASK;
|
||
|
mxcsr |= (round << _SSE_ROUND_SHIFT);
|
||
|
__ldmxcsr(mxcsr);
|
||
|
|
||
|
/* 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);
|
||
|
|
||
|
/* Store the current x87 floating-point environment */
|
||
|
__fnstenv(envp);
|
||
|
|
||
|
/* Store the MXCSR register state */
|
||
|
__stmxcsr(&envp->mxcsr);
|
||
|
|
||
|
/*
|
||
|
* When an FNSTENV instruction is executed, all pending exceptions are
|
||
|
* essentially lost (either the x87 FPU status register is cleared or all
|
||
|
* exceptions are masked).
|
||
|
*
|
||
|
* 8.6 X87 FPU EXCEPTION SYNCHRONIZATION -
|
||
|
* Intel(R) 64 and IA-32 Architectures Softare Developer's Manual - Vol 1
|
||
|
*
|
||
|
*/
|
||
|
__fldcw(envp->x87.control);
|
||
|
|
||
|
/* 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)
|
||
|
{
|
||
|
uint32_t mxcsr;
|
||
|
|
||
|
_DIAGASSERT(envp != NULL);
|
||
|
|
||
|
/* Store the current x87 floating-point environment */
|
||
|
__fnstenv(envp);
|
||
|
|
||
|
/* Clear all exception flags in FPU */
|
||
|
__fnclex();
|
||
|
|
||
|
/* Store the MXCSR register state */
|
||
|
__stmxcsr(&envp->mxcsr);
|
||
|
|
||
|
/* Clear exception flags in MXCSR XXX */
|
||
|
mxcsr = envp->mxcsr;
|
||
|
mxcsr &= ~FE_ALL_EXCEPT;
|
||
|
|
||
|
/* Mask all exceptions */
|
||
|
mxcsr |= FE_ALL_EXCEPT << _SSE_EMASK_SHIFT;
|
||
|
|
||
|
__ldmxcsr(mxcsr);
|
||
|
|
||
|
/* 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)
|
||
|
{
|
||
|
fenv_t fenv;
|
||
|
|
||
|
_DIAGASSERT(envp != NULL);
|
||
|
|
||
|
/* Store the x87 floating-point environment */
|
||
|
memset(&fenv, 0, sizeof fenv);
|
||
|
__fnstenv(&fenv);
|
||
|
|
||
|
__fe_dfl_env.x87.control = (fenv.x87.control & 0xffff0000)
|
||
|
| (__fe_dfl_env.x87.control & 0x0000ffff);
|
||
|
__fe_dfl_env.x87.status = (fenv.x87.status & 0xffff0000)
|
||
|
| (__fe_dfl_env.x87.status & 0x0000ffff);
|
||
|
__fe_dfl_env.x87.tag = (fenv.x87.tag & 0xffff0000)
|
||
|
| (__fe_dfl_env.x87.tag & 0x0000ffff);
|
||
|
__fe_dfl_env.x87.others[3] = (fenv.x87.others[3] & 0xffff0000)
|
||
|
| (__fe_dfl_env.x87.others[3] & 0x0000ffff);
|
||
|
__fldenv(*envp);
|
||
|
|
||
|
/* Store the MXCSR register */
|
||
|
__ldmxcsr(envp->mxcsr);
|
||
|
|
||
|
/* 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)
|
||
|
{
|
||
|
fenv_t fenv;
|
||
|
uint32_t mxcsr;
|
||
|
uint16_t sw;
|
||
|
|
||
|
_DIAGASSERT(envp != NULL);
|
||
|
|
||
|
/* Store the x87 floating-point environment */
|
||
|
memset(&fenv, 0, sizeof(fenv));
|
||
|
__fnstenv(&fenv);
|
||
|
|
||
|
__fe_dfl_env.x87.control = (fenv.x87.control & 0xffff0000)
|
||
|
| (__fe_dfl_env.x87.control & 0x0000ffff);
|
||
|
__fe_dfl_env.x87.status = (fenv.x87.status & 0xffff0000)
|
||
|
| (__fe_dfl_env.x87.status & 0x0000ffff);
|
||
|
__fe_dfl_env.x87.tag = (fenv.x87.tag & 0xffff0000)
|
||
|
| (__fe_dfl_env.x87.tag & 0x0000ffff);
|
||
|
__fe_dfl_env.x87.others[3] = (fenv.x87.others[3] & 0xffff0000)
|
||
|
| (__fe_dfl_env.x87.others[3] & 0x0000ffff);
|
||
|
|
||
|
/* Store the x87 status register */
|
||
|
__fnstsw(&sw);
|
||
|
|
||
|
/* Store the MXCSR register */
|
||
|
__stmxcsr(&mxcsr);
|
||
|
|
||
|
/* Install new floating-point environment */
|
||
|
fesetenv(envp);
|
||
|
|
||
|
/* Raise any previously accumulated exceptions */
|
||
|
feraiseexcept((sw | mxcsr) & FE_ALL_EXCEPT);
|
||
|
|
||
|
/* Success */
|
||
|
return (0);
|
||
|
}
|
||
|
|
||
|
/*
|
||
|
* The following functions are extentions to the standard
|
||
|
*/
|
||
|
int
|
||
|
feenableexcept(int mask)
|
||
|
{
|
||
|
uint32_t mxcsr, omask;
|
||
|
uint16_t control;
|
||
|
|
||
|
_DIAGASSERT((mask & ~FE_ALL_EXCEPT) == 0);
|
||
|
mask &= FE_ALL_EXCEPT;
|
||
|
|
||
|
__fnstcw(&control);
|
||
|
__stmxcsr(&mxcsr);
|
||
|
|
||
|
omask = (control | mxcsr >> _SSE_EMASK_SHIFT) & FE_ALL_EXCEPT;
|
||
|
control &= ~mask;
|
||
|
__fldcw(control);
|
||
|
|
||
|
mxcsr &= ~(mask << _SSE_EMASK_SHIFT);
|
||
|
__ldmxcsr(mxcsr);
|
||
|
|
||
|
return (~omask);
|
||
|
|
||
|
}
|
||
|
|
||
|
int
|
||
|
fedisableexcept(int mask)
|
||
|
{
|
||
|
uint32_t mxcsr, omask;
|
||
|
uint16_t control;
|
||
|
|
||
|
_DIAGASSERT((mask & ~FE_ALL_EXCEPT) == 0);
|
||
|
|
||
|
__fnstcw(&control);
|
||
|
__stmxcsr(&mxcsr);
|
||
|
|
||
|
omask = (control | mxcsr >> _SSE_EMASK_SHIFT) & FE_ALL_EXCEPT;
|
||
|
control |= mask;
|
||
|
__fldcw(control);
|
||
|
|
||
|
mxcsr |= mask << _SSE_EMASK_SHIFT;
|
||
|
__ldmxcsr(mxcsr);
|
||
|
|
||
|
return (~omask);
|
||
|
}
|
||
|
|
||
|
int
|
||
|
fegetexcept(void)
|
||
|
{
|
||
|
uint16_t control;
|
||
|
|
||
|
/*
|
||
|
* We assume that the masks for the x87 and the SSE unit are
|
||
|
* the same.
|
||
|
*/
|
||
|
__fnstcw(&control);
|
||
|
|
||
|
return (control & FE_ALL_EXCEPT);
|
||
|
}
|
||
|
|