// ============================================================================
//
// Copyright (c) 1997 The CGAL Consortium
//
// This software and related documentation is part of an INTERNAL release
// of the Computational Geometry Algorithms Library (CGAL). It is not
// intended for general use.
//
// ----------------------------------------------------------------------------
//
// release       :
// release_date  :
//
// file          : include/CGAL/_FPU.h
// revision      : 1.3
// revision_date : 6 February 1998
// author(s)     : Sylvain Pion <Sylvain.Pion@sophia.inria.fr>
//
// coordinator   : INRIA Sophia-Antipolis (<Herve.Bronnimann@sophia.inria.fr>)
//
// ============================================================================

#ifndef _FPU_H
#define _FPU_H

/*
 * Specify some *very* platform dependant functions, regarding the FPU
 * directed rounding modes. There is only support for double precision.
 *
 * I try to make it work with gcc/g++/cc/CC.
 * And I also try to provide the equivalent assembly code for GNU C.
 *
 * TODO: Check the exception flags, according to Christoph's remarks/code.
 *        (ie should we erase all, should we save&restore, etc...)
 */

#if defined(__osf__)
#undef __osf
#define __osf
#endif

#if defined(__i386__) || defined(i386)	/* Needed by egcs */
#undef __i386
#define __i386
#endif

#if (!defined(__i386)&&!defined(__sparc)&&!defined(__alpha)&&!defined(__mips))
#error "Architecture not recognized."
#endif

#if ( (defined(__i386) || defined(__sparc) || defined(__alpha)) && \
      defined(__GNUC__))
#define __USE_ASSEMBLY
#endif

#ifndef __USE_ASSEMBLY
#ifdef __linux
#include <fpu_control.h>
#endif
#ifdef __osf
#include <float.h>
#endif
#ifdef __sgi
  /* This #define is forced for backward compatibility with Irix 5.3. */
  /* I think it slows down Irix 6.2... */
#define __SGI_ieeefph__
#ifdef __SGI_ieeefph__
#include <ieeefp.h>
#else
#include <sys/fpu.h>
#endif
#endif
#ifdef __sun
#include <ieeefp.h>
#endif
#else	/* __USE_ASSEMBLY */
#ifdef __i386
#define SETFPCW(CW) asm volatile ("fldcw %0" : : "m" (*&CW))
/* x86:                       rounding   | precision  | default mask */
static unsigned int _FPU_cw_zero = 0xC00      | 0x200      | 0x107f; 
static unsigned int _FPU_cw_near = 0x0        | 0x200      | 0x107f;
static unsigned int _FPU_cw_up   = 0x800      | 0x200      | 0x107f; 
static unsigned int _FPU_cw_down = 0x400      | 0x200      | 0x107f;
#endif
#ifdef __sparc
#define SETFPCW(CW) asm volatile ("ld %0,%%fsr" : "=m" (*&CW))
/* Sparc:                     rounding   | precision  | default mask */
static unsigned int _FPU_cw_zero = 0x40000000 | 0x20000000 | 0x1f;
static unsigned int _FPU_cw_near = 0x0        | 0x20000000 | 0x1f;
static unsigned int _FPU_cw_up   = 0x80000000 | 0x20000000 | 0x1f;
static unsigned int _FPU_cw_down = 0xc0000000 | 0x20000000 | 0x1f;
#endif
#ifdef __alpha
#define SETFPCW(CW) asm volatile ("mt_fpcr %0; excb" : : "f"(CW))
/* Alpha:                      rounding */
static unsigned long _FPU_cw_zero = 0x0000000000000000UL;
static unsigned long _FPU_cw_near = 0x0800000000000000UL;
static unsigned long _FPU_cw_up   = 0x0c00000000000000UL;
static unsigned long _FPU_cw_down = 0x0400000000000000UL;
#endif
#endif

#if !defined(__GNUC__) && !defined(__cplusplus)
#define inline /* */
#endif

static inline void _FPU_set_rounding_to_zero (void);
static inline void _FPU_set_rounding_to_nearest (void);
static inline void _FPU_set_rounding_to_infinity (void);
static inline void _FPU_set_rounding_to_minus_infinity (void);


/* Code of those inline functions: */

static inline void _FPU_set_rounding_to_zero (void)
{
#ifdef __USE_ASSEMBLY
	SETFPCW(_FPU_cw_zero);
#else
#ifdef __linux
#ifdef __i386 
        __setfpucw(0x1e72);
#else
        __setfpucw(0x1f72);	/* FIX ME */
#endif
#endif

#ifdef __osf
	write_rnd(FP_RND_RZ);
#endif

#ifdef __sun
        fpsetround(FP_RZ);
#endif

#ifdef __sgi
#ifdef __SGI_ieeefph__
	fp_rnd mode = FP_RZ;
	fpsetround(mode);
#else
	union fpc_csr fpu_ctl;
	fpu_ctl.fc_word = get_fpc_csr();
	fpu_ctl.fc_struct.rounding_mode = ROUND_TO_ZERO;
	set_fpc_csr (fpu_ctl.fc_word);
#endif
#endif
#endif
}

static inline void _FPU_set_rounding_to_nearest (void)
{
#ifdef __USE_ASSEMBLY
	SETFPCW(_FPU_cw_near);
#else
#ifdef __osf
	write_rnd(FP_RND_RN);
#endif

#ifdef __sun
	fpsetround(FP_RN);
#endif

#ifdef __linux
#ifdef __i386
	__setfpucw(0x1272);
#else
	__setfpucw(0x1372);
#endif
#endif

#ifdef __sgi
#ifdef __SGI_ieeefph__
	fp_rnd mode = FP_RN;
	fpsetround(mode);
#else
	union fpc_csr fpu_ctl;
	fpu_ctl.fc_word = get_fpc_csr();
	fpu_ctl.fc_struct.rounding_mode = ROUND_TO_NEAREST;
	set_fpc_csr (fpu_ctl.fc_word);
#endif
#endif
#endif
}

static inline void _FPU_set_rounding_to_infinity (void)
{
#ifdef __USE_ASSEMBLY
	SETFPCW(_FPU_cw_up);
#else
#ifdef __osf
	write_rnd(FP_RND_RP);
#endif

#ifdef __sun
        fpsetround(FP_RP);
#endif

#ifdef __linux
#ifdef __i386
	__setfpucw(0x1a72);
#else
	__setfpucw(0x1b72);
#endif
#endif

#ifdef __sgi
#ifdef __SGI_ieeefph__
	fp_rnd mode = FP_RP;
	fpsetround(mode);
#else
	union fpc_csr fpu_ctl;
	fpu_ctl.fc_word = get_fpc_csr();
	fpu_ctl.fc_struct.rounding_mode = ROUND_TO_PLUS_INFINITY;
	set_fpc_csr (fpu_ctl.fc_word);
#endif
#endif
#endif
}

static inline void _FPU_set_rounding_to_minus_infinity (void)
{
#ifdef __USE_ASSEMBLY
	SETFPCW(_FPU_cw_down);
#else
#ifdef __osf
	write_rnd(FP_RND_RM);
#endif

#ifdef __sun
        fpsetround(FP_RM);
#endif

#ifdef __linux
#ifdef __i386
        __setfpucw(0x1672);
#else
        __setfpucw(0x1772);
#endif
#endif

#ifdef __sgi
#ifdef __SGI_ieeefph__
	fp_rnd mode = FP_RM;
	fpsetround(mode);
#else
	union fpc_csr fpu_ctl;
	fpu_ctl.fc_word = get_fpc_csr();
	fpu_ctl.fc_struct.rounding_mode = ROUND_TO_MINUS_INFINITY;
	set_fpc_csr (fpu_ctl.fc_word);
#endif
#endif
#endif
}

#endif /* _FPU_H */