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/* Internal libc stuff for floating point environment routines.
Copyright (C) 1997 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#ifndef _FENV_LIBC_H
#define _FENV_LIBC_H 1
#include <fenv.h>
/* The sticky bits in the FPSCR indicating exceptions have occurred. */
#define FPSCR_STICKY_BITS ((FE_ALL_EXCEPT | FE_ALL_INVALID) & ~FE_INVALID)
/* Equivalent to fegetenv, but returns a fenv_t instead of taking a
pointer. */
#define fegetenv_register() \
({ fenv_t env; asm volatile ("mffs %0" : "=f" (env)); env; })
/* Equivalent to fesetenv, but takes a fenv_t instead of a pointer. */
#define fesetenv_register(env) \
({ double d = (env); asm volatile ("mtfsf 0xff,%0" : : "f" (d)); })
/* This very handy macro:
- Sets the rounding mode to 'round to nearest';
- Sets the processor into IEEE mode; and
- Prevents exceptions from being raised for inexact results.
These things happen to be exactly what you need for typical elementary
functions. */
#define relax_fenv_state() asm ("mtfsfi 7,0")
/* Set/clear a particular FPSCR bit (for instance,
reset_fpscr_bit(FPSCR_VE);
prevents INVALID exceptions from being raised). */
#define set_fpscr_bit(x) asm volatile ("mtfsb1 %0" : : "i"(x))
#define reset_fpscr_bit(x) asm volatile ("mtfsb0 %0" : : "i"(x))
typedef union
{
fenv_t fenv;
unsigned int l[2];
} fenv_union_t;
/* Definitions of all the FPSCR bit numbers */
enum {
FPSCR_FX = 0, /* exception summary */
FPSCR_FEX, /* enabled exception summary */
FPSCR_VX, /* invalid operation summary */
FPSCR_OX, /* overflow */
FPSCR_UX, /* underflow */
FPSCR_ZX, /* zero divide */
FPSCR_XX, /* inexact */
FPSCR_VXSNAN, /* invalid operation for SNaN */
FPSCR_VXISI, /* invalid operation for Inf-Inf */
FPSCR_VXIDI, /* invalid operation for Inf/Inf */
FPSCR_VXZDZ, /* invalid operation for 0/0 */
FPSCR_VXIMZ, /* invalid operation for Inf*0 */
FPSCR_VXVC, /* invalid operation for invalid compare */
FPSCR_FR, /* fraction rounded [fraction was incremented by round] */
FPSCR_FI, /* fraction inexact */
FPSCR_FPRF_C, /* result class descriptor */
FPSCR_FPRF_FL, /* result less than (usually, less than 0) */
FPSCR_FPRF_FG, /* result greater than */
FPSCR_FPRF_FE, /* result equal to */
FPSCR_FPRF_FU, /* result unordered */
FPSCR_20, /* reserved */
FPSCR_VXSOFT, /* invalid operation set by software */
FPSCR_VXSQRT, /* invalid operation for square root */
FPSCR_VXCVI, /* invalid operation for invalid integer convert */
FPSCR_VE, /* invalid operation exception enable */
FPSCR_OE, /* overflow exception enable */
FPSCR_UE, /* underflow exception enable */
FPSCR_ZE, /* zero divide exception enable */
FPSCR_XE, /* inexact exception enable */
FPSCR_NI /* non-IEEE mode (typically, no denormalised numbers) */
/* the remaining two least-significant bits keep the rounding mode */
};
/* This operation (i) sets the appropriate FPSCR bits for its
parameter, (ii) converts SNaN to the corresponding NaN, and (iii)
otherwise passes its parameter through unchanged (in particular, -0
and +0 stay as they were). The `obvious' way to do this is optimised
out by gcc. */
#define f_wash(x) \
({ double d; asm volatile ("fmul %0,%1,%2" \
: "=f"(d) \
: "f" (x), "f"((float)1.0)); d; })
#define f_washf(x) \
({ float f; asm volatile ("fmuls %0,%1,%2" \
: "=f"(f) \
: "f" (x), "f"((float)1.0)); f; })
#endif /* fenv_libc.h */
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