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