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+/*
+ * Copyright (c) 2002 Apple Computer, Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * The contents of this file constitute Original Code as defined in and
+ * are subject to the Apple Public Source License Version 1.1 (the
+ * "License"). You may not use this file except in compliance with the
+ * License. Please obtain a copy of the License at
+ * http://www.apple.com/publicsource and read it before using this file.
+ *
+ * This Original Code and all software distributed under the License are
+ * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
+ * License for the specific language governing rights and limitations
+ * under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+/*******************************************************************************
+* *
+* File: fenv.h *
+* *
+* Contains: typedefs and prototypes for C99 floating point environment. *
+* *
+*******************************************************************************/
+
+#ifndef __FENV__
+#define __FENV__
+
+#if defined(__GNUC__) && (__GNUC__ >= 4)
+#pragma GCC fenv
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ A collection of functions designed to provide access to the floating
+ point environment for numerical programming. It is compliant with
+ the floating-point requirements in C99.
+
+ Earlier versions of fenv.h were merely "modeled after" C9X. Many of the functions
+ that formerly returned ints now return void to be standard compliant.
+
+ Note: There are actually two physical floating point environments on x86. There
+ is the one described by the x87 floating point control and status words, which applies
+ primarily to calculations done with long double on MacOS X for Intel. There is the
+ MXCSR which applies primarily to calculations done with scalar float, scalar double
+ and SSE/SSE2/SSE3. The high level interface, which uses FE_ macros as int arguments
+ to configure the fexcep_t, returns and works with values that represents the logical
+ OR of these two sets of flags or masks. That is, if a flag or mask is set in either
+ environment, it will be set in fexcept_t when the state is read. Likewise, setting
+ the mask using a fexcep_t will set that mask on both environments. For this reason,
+ changing the value of the MXCSR state or floating point control/status word state on
+ your own will make the results of the functions declared in this header undefined.
+ See below for details about how and when. Exception: you may change the FZ, DAZ, DE
+ and DM bits in the MXCSR independent of this interface and retain defined behavior,
+ so long as you do not change the other bits. It is suggested that developers who wish
+ this level of control access the bits in the fenv_t directly. They are direct copies
+ of the hardware special purpose registers of similar name. Please consult appropriate
+ Intel documentation for the processor about the meaning of various bits in each register.
+
+ The file <fenv.h> declares many functions in support of numerical
+ programming. Programs that test flags or run under
+ non-default modes must do so under the effect of an enabling
+ "fenv_access" pragma.
+*/
+
+/********************************************************************************
+* *
+* fenv_t is a type for representing the entire floating-point *
+* environment in a single object. *
+* *
+* fexcept_t is a type for representing the floating-point *
+* exception flag state collectively. *
+* *
+********************************************************************************/
+typedef struct {
+ unsigned short __control; /* A direct copy of the floaing point control word */
+ unsigned short __status; /* A direct copy of the floaing point status word */
+ unsigned int __mxcsr; /* A direct copy of the MXCSR */
+ char __reserved[8]; /* Reserved for future expansion. */
+} fenv_t;
+
+typedef unsigned short fexcept_t;
+
+/* Definitions of floating-point exception macros */
+enum {
+ _FE_INEXACT = 0x0020,
+ _FE_DIVBYZERO = 0x0004,
+ _FE_UNDERFLOW = 0x0010,
+ _FE_OVERFLOW = 0x0008,
+ _FE_INVALID = 0x0001,
+ _FE_ALL_EXCEPT = 0x003D /* FE_INEXACT | FE_DIVBYZERO | FE_UNDERFLOW | FE_OVERFLOW | FE_INVALID*/
+};
+
+#define FE_INEXACT _FE_INEXACT
+#define FE_DIVBYZERO _FE_DIVBYZERO
+#define FE_UNDERFLOW _FE_UNDERFLOW
+#define FE_OVERFLOW _FE_OVERFLOW
+#define FE_INVALID _FE_INVALID
+#define FE_ALL_EXCEPT _FE_ALL_EXCEPT
+
+/* Definitions of rounding direction macros */
+enum {
+ _FE_TONEAREST = 0x0000,
+ _FE_TOWARDZERO = 0x0C00,
+ _FE_UPWARD = 0x0800,
+ _FE_DOWNWARD = 0x0400
+};
+
+#define FE_TONEAREST _FE_TONEAREST
+#define FE_TOWARDZERO _FE_TOWARDZERO
+#define FE_UPWARD _FE_UPWARD
+#define FE_DOWNWARD _FE_DOWNWARD
+
+/* default environment object */
+extern const fenv_t _FE_DFL_ENV;
+#define FE_DFL_ENV &_FE_DFL_ENV /* pointer to default environment */
+
+/*******************************************************************************
+* A environment object that sets to defualt settings and in addition sets the *
+* FZ and DAZ bits in the MXCSR, which causes flush-to-zero behavior of *
+* denormals. When using this environment, denormals encountered by XMM based *
+* calculation (which normally should be all single and double precision scalar *
+* floating point calculations, and all SSE/SSE2/SSE3 computation) will be *
+* treated as zero. Calculation results that are denormals will also be *
+* truncated to zero. This calculation mode is not IEEE-754 compliant, but may *
+* prevent lengthy stalls that occur in code that encounters denormals. It is *
+* suggested that you do not use this mode unless you have established that *
+* denormals are causing trouble for your code. Please use wisely. *
+* *
+* It is not possible to disable denorm stalls on calculation using the x87 FPU.*
+*******************************************************************************/
+extern const fenv_t _FE_DFL_DISABLE_SSE_DENORMS_ENV;
+#define FE_DFL_DISABLE_SSE_DENORMS_ENV &_FE_DFL_DISABLE_SSE_DENORMS_ENV
+
+/*******************************************************************************
+* The following functions provide high level access to the exception flags.*
+* The "int" input argument can be constructed by bitwise ORs of the *
+* exception macros: for example: FE_OVERFLOW | FE_INEXACT. *
+*******************************************************************************/
+
+/*******************************************************************************
+* The function "feclearexcept" clears the supported floating point *
+* exceptions represented by its argument. *
+*******************************************************************************/
+
+extern int feclearexcept(int /*excepts*/);
+
+
+/*******************************************************************************
+* The function "fegetexceptflag" stores a implementation-defined *
+* representation of the states of the floating-point status flags indicated *
+* by its integer argument excepts in the object pointed to by the argument, *
+* flagp. *
+*******************************************************************************/
+
+extern int fegetexceptflag(fexcept_t * /*flagp*/, int /*excepts*/);
+
+
+/*******************************************************************************
+* The function "feraiseexcept" raises the supported floating-point *
+* exceptions represented by its argument. The order in which these *
+* floating-point exceptions are raised is unspecified. *
+*******************************************************************************/
+
+extern int feraiseexcept(int /*excepts*/);
+
+
+/*******************************************************************************
+* The function "fesetexceptflag" sets or clears the floating point status *
+* flags indicated by the argument excepts to the states stored in the *
+* object pointed to by flagp. The value of the *flagp shall have been set *
+* by a previous call to fegetexceptflag whose second argument represented *
+* at least those floating-point exceptions represented by the argument *
+* excepts. This function does not raise floating-point exceptions; it just *
+* sets the state of the flags. *
+*******************************************************************************/
+
+extern int fesetexceptflag(const fexcept_t * /*flagp*/, int /*excepts*/);
+
+
+/*******************************************************************************
+* The function "fetestexcept" determines which of the specified subset of *
+* the floating-point exception flags are currently set. The excepts *
+* argument specifies the floating-point status flags to be queried. This *
+* function returns the value of the bitwise OR of the floating-point *
+* exception macros corresponding to the currently set floating-point *
+* exceptions included in excepts. *
+* *
+* On MacOS X for Intel, the result is the value of union of the *
+* corresponding result from the x87 and SSE floating point states. *
+*******************************************************************************/
+
+extern int fetestexcept(int /*excepts*/);
+
+
+/*******************************************************************************
+* The following functions provide control of rounding direction modes. *
+*******************************************************************************/
+
+/*******************************************************************************
+* The function "fegetround" returns the value of the rounding direction *
+* macro which represents the current rounding direction, or a negative *
+* if there is no such rounding direction macro or the current rounding *
+* direction is not determinable. *
+*******************************************************************************/
+
+extern int fegetround(void);
+
+
+/*******************************************************************************
+* The function "fesetround" 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. It *
+* returns zero if and only if the argument is equal to a rounding *
+* direction macro. *
+*******************************************************************************/
+
+extern int fesetround(int /*round*/);
+
+
+/*******************************************************************************
+* The following functions manage the floating-point environment, exception *
+* flags and dynamic modes, as one entity. *
+*******************************************************************************/
+
+/*******************************************************************************
+* The fegetenv function stores the current floating-point enviornment in *
+* the object pointed to by envp. *
+*******************************************************************************/
+extern int fegetenv(fenv_t * /*envp*/);
+
+/*******************************************************************************
+* 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. The feholdexcept *
+* function returns zero if and only if non-stop floating-point exceptions *
+* handling was successfully installed. *
+*******************************************************************************/
+extern int feholdexcept(fenv_t * /*envp*/);
+
+/*******************************************************************************
+* The fesetnv function establishes the floating-point environment *
+* represented by the object pointed to by envp. The argument envp shall *
+* point to an object set by a call to fegetenv or feholdexcept, or equal to *
+* a floating-point environment macro -- we define only *FE_DFL_ENV and *
+* FE_DISABLE_SSE_DENORMS_ENV -- to be C99 standard compliant and portable *
+* to other architectures. Note that fesetnv merely installs the state of *
+* the floating-point status flags represented through its argument, and *
+* does not raise these floating-point exceptions. *
+* *
+* On MacOS X for Intel you may test and set the bits in *envp yourself, *
+* provided that you conditionalize the code appropriately to preserve *
+* portability and you follow the various strictures and suggestions *
+* provided by Intel in appropriate processor documentation. Please be aware *
+* that because there are two hardware locations for setting and reading *
+* floating point environment, this function (and others like it) are not *
+* atomic -- that is, for a brief period of time during the function call *
+* your new environment will have been applied to one but not both of the *
+* floating point engines (x87 and SSE). In addition, the behavior of some *
+* higher level interfaces (fegetround) is undefined if the x87 and SSE *
+* floating point units rounding modes are configured differently. Please *
+* use common sense. *
+*******************************************************************************/
+extern int fesetenv(const fenv_t * /*envp*/);
+
+/*******************************************************************************
+* 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. *
+* *
+* Please see the description of feholdexcept for additional ways to create *
+* a fenv_t object, which are valid only for MacOS X for Intel. *
+*******************************************************************************/
+extern int feupdateenv(const fenv_t * /*envp*/);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __FENV__ */
+
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