real.h

这是完整的gcc源代码

/* Front-end tree definitions for GNU compiler.
   Copyright (C) 1989 Free Software Foundation, Inc.

This file is part of GNU CC.

GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 1, or (at your option)
any later version.

GNU CC 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

#ifndef REAL_H_INCLUDED
#define REAL_H_INCLUDED

/* If we are not cross-compiling, use a `double' to represent the
   floating-point value.  Otherwise, use some other type
   (probably a struct containing an array of longs).  */
#ifndef REAL_VALUE_TYPE
#define REAL_VALUE_TYPE double
#else
#define REAL_IS_NOT_DOUBLE
#endif

/* Compare two floating-point values for equality.  */
#ifndef REAL_VALUES_EQUAL
#define REAL_VALUES_EQUAL(x,y) ((x) == (y))
#endif

/* Compare two floating-point values for less than.  */
#ifndef REAL_VALUES_LESS
#define REAL_VALUES_LESS(x,y) ((x) < (y))
#endif

/* Scale X by Y powers of 2.  */
#ifndef REAL_VALUE_LDEXP
#define REAL_VALUE_LDEXP(x,y) ldexp (x, y)
extern double ldexp ();
#endif

/* Convert the string X to a floating-point value.  */
#ifndef REAL_VALUE_ATOF
#define REAL_VALUE_ATOF(x) atof (x)
extern double atof ();
#endif

/* Negate the floating-point value X.  */
#ifndef REAL_VALUE_NEGATE
#define REAL_VALUE_NEGATE(x) (- (x))
#endif

/* Truncate the floating-point value X to single-precision.  */
#ifndef REAL_VALUE_TRUNCATE
#define REAL_VALUE_TRUNCATE(x) ((float) (x))
#endif

/* Union type used for extracting real values from CONST_DOUBLEs
   or putting them in.  */

union real_extract 
{
  REAL_VALUE_TYPE d;
  int i[sizeof (REAL_VALUE_TYPE) / sizeof (int)];
};

/* For a CONST_DOUBLE:
   The usual two ints that hold the value.
   For a DImode, that is all there are;
    and CONST_DOUBLE_LOW is the low-order word and ..._HIGH the high-order.
   For a float, the number of ints varies,
    and CONST_DOUBLE_LOW is the one that should come first *in memory*.
    So use &CONST_DOUBLE_LOW(r) as the address of an array of ints.  */
#define CONST_DOUBLE_LOW(r) XINT (r, 2)
#define CONST_DOUBLE_HIGH(r) XINT (r, 3)

/* Link for chain of all CONST_DOUBLEs in use in current function.  */
#define CONST_DOUBLE_CHAIN(r) XEXP (r, 1)
/* The MEM which represents this CONST_DOUBLE's value in memory,
   or const0_rtx if no MEM has been made for it yet,
   or cc0_rtx if it is not on the chain.  */
#define CONST_DOUBLE_MEM(r) XEXP (r, 0)

/* Function to return a real value (not a tree node)
   from a given integer constant.  */
REAL_VALUE_TYPE real_value_from_int_cst ();

#endif /* Not REAL_H_INCLUDED */