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      1 /* Operations with long integers.
      2    Copyright (C) 2006, 2007, 2008 Free Software Foundation, Inc.
      3 
      4 This file is part of GCC.
      5 
      6 GCC is free software; you can redistribute it and/or modify it
      7 under the terms of the GNU General Public License as published by the
      8 Free Software Foundation; either version 3, or (at your option) any
      9 later version.
     10 
     11 GCC is distributed in the hope that it will be useful, but WITHOUT
     12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
     13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
     14 for more details.
     15 
     16 You should have received a copy of the GNU General Public License
     17 along with GCC; see the file COPYING3.  If not see
     18 <http://www.gnu.org/licenses/>.  */
     19 
     20 #ifndef DOUBLE_INT_H
     21 #define DOUBLE_INT_H
     22 
     23 #ifndef GENERATOR_FILE
     24 #include <gmp.h>
     25 #endif
     26 #include "coretypes.h"
     27 
     28 /* A large integer is currently represented as a pair of HOST_WIDE_INTs.
     29    It therefore represents a number with precision of
     30    2 * HOST_BITS_PER_WIDE_INT bits (it is however possible that the
     31    internal representation will change, if numbers with greater precision
     32    are needed, so the users should not rely on it).  The representation does
     33    not contain any information about signedness of the represented value, so
     34    it can be used to represent both signed and unsigned numbers.  For
     35    operations where the results depend on signedness (division, comparisons),
     36    it must be specified separately.  For each such operation, there are three
     37    versions of the function -- double_int_op, that takes an extra UNS argument
     38    giving the signedness of the values, and double_int_sop and double_int_uop
     39    that stand for its specializations for signed and unsigned values.
     40 
     41    You may also represent with numbers in smaller precision using double_int.
     42    You however need to use double_int_ext (that fills in the bits of the
     43    number over the prescribed precision with zeros or with the sign bit) before
     44    operations that do not perform arithmetics modulo 2^precision (comparisons,
     45    division), and possibly before storing the results, if you want to keep
     46    them in some canonical form).  In general, the signedness of double_int_ext
     47    should match the signedness of the operation.
     48 
     49    ??? The components of double_int differ in signedness mostly for
     50    historical reasons (they replace an older structure used to represent
     51    numbers with precision higher than HOST_WIDE_INT).  It might be less
     52    confusing to have them both signed or both unsigned.  */
     53 
     54 typedef struct
     55 {
     56   unsigned HOST_WIDE_INT low;
     57   HOST_WIDE_INT high;
     58 } double_int;
     59 
     60 union tree_node;
     61 
     62 /* Constructors and conversions.  */
     63 
     64 union tree_node *double_int_to_tree (union tree_node *, double_int);
     65 bool double_int_fits_to_tree_p (const union tree_node *, double_int);
     66 double_int tree_to_double_int (const union tree_node *);
     67 
     68 /* Constructs double_int from integer CST.  The bits over the precision of
     69    HOST_WIDE_INT are filled with the sign bit.  */
     70 
     71 static inline double_int
     72 shwi_to_double_int (HOST_WIDE_INT cst)
     73 {
     74   double_int r;
     75 
     76   r.low = (unsigned HOST_WIDE_INT) cst;
     77   r.high = cst < 0 ? -1 : 0;
     78 
     79   return r;
     80 }
     81 
     82 /* Some useful constants.  */
     83 
     84 #define double_int_minus_one (shwi_to_double_int (-1))
     85 #define double_int_zero (shwi_to_double_int (0))
     86 #define double_int_one (shwi_to_double_int (1))
     87 #define double_int_two (shwi_to_double_int (2))
     88 #define double_int_ten (shwi_to_double_int (10))
     89 
     90 /* Constructs double_int from unsigned integer CST.  The bits over the
     91    precision of HOST_WIDE_INT are filled with zeros.  */
     92 
     93 static inline double_int
     94 uhwi_to_double_int (unsigned HOST_WIDE_INT cst)
     95 {
     96   double_int r;
     97 
     98   r.low = cst;
     99   r.high = 0;
    100 
    101   return r;
    102 }
    103 
    104 /* The following operations perform arithmetics modulo 2^precision,
    105    so you do not need to call double_int_ext between them, even if
    106    you are representing numbers with precision less than
    107    2 * HOST_BITS_PER_WIDE_INT bits.  */
    108 
    109 double_int double_int_mul (double_int, double_int);
    110 double_int double_int_add (double_int, double_int);
    111 double_int double_int_neg (double_int);
    112 
    113 /* You must ensure that double_int_ext is called on the operands
    114    of the following operations, if the precision of the numbers
    115    is less than 2 * HOST_BITS_PER_WIDE_INT bits.  */
    116 bool double_int_fits_in_hwi_p (double_int, bool);
    117 bool double_int_fits_in_shwi_p (double_int);
    118 bool double_int_fits_in_uhwi_p (double_int);
    119 HOST_WIDE_INT double_int_to_shwi (double_int);
    120 unsigned HOST_WIDE_INT double_int_to_uhwi (double_int);
    121 double_int double_int_div (double_int, double_int, bool, unsigned);
    122 double_int double_int_sdiv (double_int, double_int, unsigned);
    123 double_int double_int_udiv (double_int, double_int, unsigned);
    124 double_int double_int_mod (double_int, double_int, bool, unsigned);
    125 double_int double_int_smod (double_int, double_int, unsigned);
    126 double_int double_int_umod (double_int, double_int, unsigned);
    127 double_int double_int_divmod (double_int, double_int, bool, unsigned, double_int *);
    128 double_int double_int_sdivmod (double_int, double_int, unsigned, double_int *);
    129 double_int double_int_udivmod (double_int, double_int, unsigned, double_int *);
    130 bool double_int_negative_p (double_int);
    131 int double_int_cmp (double_int, double_int, bool);
    132 int double_int_scmp (double_int, double_int);
    133 int double_int_ucmp (double_int, double_int);
    134 void dump_double_int (FILE *, double_int, bool);
    135 
    136 /* Zero and sign extension of numbers in smaller precisions.  */
    137 
    138 double_int double_int_ext (double_int, unsigned, bool);
    139 double_int double_int_sext (double_int, unsigned);
    140 double_int double_int_zext (double_int, unsigned);
    141 double_int double_int_mask (unsigned);
    142 
    143 #define ALL_ONES (~((unsigned HOST_WIDE_INT) 0))
    144 
    145 /* The operands of the following comparison functions must be processed
    146    with double_int_ext, if their precision is less than
    147    2 * HOST_BITS_PER_WIDE_INT bits.  */
    148 
    149 /* Returns true if CST is zero.  */
    150 
    151 static inline bool
    152 double_int_zero_p (double_int cst)
    153 {
    154   return cst.low == 0 && cst.high == 0;
    155 }
    156 
    157 /* Returns true if CST is one.  */
    158 
    159 static inline bool
    160 double_int_one_p (double_int cst)
    161 {
    162   return cst.low == 1 && cst.high == 0;
    163 }
    164 
    165 /* Returns true if CST is minus one.  */
    166 
    167 static inline bool
    168 double_int_minus_one_p (double_int cst)
    169 {
    170   return (cst.low == ALL_ONES && cst.high == -1);
    171 }
    172 
    173 /* Returns true if CST1 == CST2.  */
    174 
    175 static inline bool
    176 double_int_equal_p (double_int cst1, double_int cst2)
    177 {
    178   return cst1.low == cst2.low && cst1.high == cst2.high;
    179 }
    180 
    181 #ifndef GENERATOR_FILE
    182 /* Conversion to and from GMP integer representations.  */
    183 
    184 void mpz_set_double_int (mpz_t, double_int, bool);
    185 double_int mpz_get_double_int (const_tree, mpz_t, bool);
    186 #endif
    187 
    188 #endif /* DOUBLE_INT_H */
    189