gcc/double-int.h

   1 /* Operations with long integers.
   2    Copyright (C) 2006, 2007 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 #include <gmp.h>
  24 #include "coretypes.h"
  25
  26 /* A large integer is currently represented as a pair of HOST_WIDE_INTs.
  27    It therefore represents a number with precision of
  28    2 * HOST_BITS_PER_WIDE_INT bits (it is however possible that the
  29    internal representation will change, if numbers with greater precision
  30    are needed, so the users should not rely on it).  The representation does
  31    not contain any information about signedness of the represented value, so
  32    it can be used to represent both signed and unsigned numbers.  For
  33    operations where the results depend on signedness (division, comparisons),
  34    it must be specified separately.  For each such operation, there are three
  35    versions of the function -- double_int_op, that takes an extra UNS argument
  36    giving the signedness of the values, and double_int_sop and double_int_uop
  37    that stand for its specializations for signed and unsigned values.
  38
  39    You may also represent with numbers in smaller precision using double_int.
  40    You however need to use double_int_ext (that fills in the bits of the
  41    number over the prescribed precision with zeros or with the sign bit) before
  42    operations that do not perform arithmetics modulo 2^precision (comparisons,
  43    division), and possibly before storing the results, if you want to keep
  44    them in some canonical form).  In general, the signedness of double_int_ext
  45    should match the signedness of the operation.
  46
  47    ??? The components of double_int differ in signedness mostly for
  48    historical reasons (they replace an older structure used to represent
  49    numbers with precision higher than HOST_WIDE_INT).  It might be less
  50    confusing to have them both signed or both unsigned.  */
  51
  52 typedef struct
  53 {
  54   unsigned HOST_WIDE_INT low;
  55   HOST_WIDE_INT high;
  56 } double_int;
  57
  58 union tree_node;
  59
  60 /* Constructors and conversions.  */
  61
  62 union tree_node *double_int_to_tree (union tree_node *, double_int);
  63 bool double_int_fits_to_tree_p (const union tree_node *, double_int);
  64 double_int tree_to_double_int (const union tree_node *);
  65
  66 /* Constructs double_int from integer CST.  The bits over the precision of
  67    HOST_WIDE_INT are filled with the sign bit.  */
  68
  69 static inline double_int
  70 shwi_to_double_int (HOST_WIDE_INT cst)
  71 {
  72   double_int r;
  73
  74   r.low = (unsigned HOST_WIDE_INT) cst;
  75   r.high = cst < 0 ? -1 : 0;
  76
  77   return r;
  78 }
  79
  80 /* Some useful constants.  */
  81
  82 #define double_int_minus_one (shwi_to_double_int (-1))
  83 #define double_int_zero (shwi_to_double_int (0))
  84 #define double_int_one (shwi_to_double_int (1))
  85 #define double_int_two (shwi_to_double_int (2))
  86 #define double_int_ten (shwi_to_double_int (10))
  87
  88 /* Constructs double_int from unsigned integer CST.  The bits over the
  89    precision of HOST_WIDE_INT are filled with zeros.  */
  90
  91 static inline double_int
  92 uhwi_to_double_int (unsigned HOST_WIDE_INT cst)
  93 {
  94   double_int r;
  95
  96   r.low = cst;
  97   r.high = 0;
  98
  99   return r;
 100 }
 101
 102 /* The following operations perform arithmetics modulo 2^precision,
 103    so you do not need to call double_int_ext between them, even if
 104    you are representing numbers with precision less than
 105    2 * HOST_BITS_PER_WIDE_INT bits.  */
 106
 107 double_int double_int_mul (double_int, double_int);
 108 double_int double_int_add (double_int, double_int);
 109 double_int double_int_neg (double_int);
 110
 111 /* You must ensure that double_int_ext is called on the operands
 112    of the following operations, if the precision of the numbers
 113    is less than 2 * HOST_BITS_PER_WIDE_INT bits.  */
 114 bool double_int_fits_in_hwi_p (double_int, bool);
 115 bool double_int_fits_in_shwi_p (double_int);
 116 bool double_int_fits_in_uhwi_p (double_int);
 117 HOST_WIDE_INT double_int_to_shwi (double_int);
 118 unsigned HOST_WIDE_INT double_int_to_uhwi (double_int);
 119 double_int double_int_div (double_int, double_int, bool, unsigned);
 120 double_int double_int_sdiv (double_int, double_int, unsigned);
 121 double_int double_int_udiv (double_int, double_int, unsigned);
 122 double_int double_int_mod (double_int, double_int, bool, unsigned);
 123 double_int double_int_smod (double_int, double_int, unsigned);
 124 double_int double_int_umod (double_int, double_int, unsigned);
 125 double_int double_int_divmod (double_int, double_int, bool, unsigned, double_int *);
 126 double_int double_int_sdivmod (double_int, double_int, unsigned, double_int *);
 127 double_int double_int_udivmod (double_int, double_int, unsigned, double_int *);
 128 bool double_int_negative_p (double_int);
 129 int double_int_cmp (double_int, double_int, bool);
 130 int double_int_scmp (double_int, double_int);
 131 int double_int_ucmp (double_int, double_int);
 132 void dump_double_int (FILE *, double_int, bool);
 133
 134 /* Zero and sign extension of numbers in smaller precisions.  */
 135
 136 double_int double_int_ext (double_int, unsigned, bool);
 137 double_int double_int_sext (double_int, unsigned);
 138 double_int double_int_zext (double_int, unsigned);
 139 double_int double_int_mask (unsigned);
 140
 141 #define ALL_ONES (~((unsigned HOST_WIDE_INT) 0))
 142
 143 /* The operands of the following comparison functions must be processed
 144    with double_int_ext, if their precision is less than
 145    2 * HOST_BITS_PER_WIDE_INT bits.  */
 146
 147 /* Returns true if CST is zero.  */
 148
 149 static inline bool
 150 double_int_zero_p (double_int cst)
 151 {
 152   return cst.low == 0 && cst.high == 0;
 153 }
 154
 155 /* Returns true if CST is one.  */
 156
 157 static inline bool
 158 double_int_one_p (double_int cst)
 159 {
 160   return cst.low == 1 && cst.high == 0;
 161 }
 162
 163 /* Returns true if CST is minus one.  */
 164
 165 static inline bool
 166 double_int_minus_one_p (double_int cst)
 167 {
 168   return (cst.low == ALL_ONES && cst.high == -1);
 169 }
 170
 171 /* Returns true if CST1 == CST2.  */
 172
 173 static inline bool
 174 double_int_equal_p (double_int cst1, double_int cst2)
 175 {
 176   return cst1.low == cst2.low && cst1.high == cst2.high;
 177 }
 178
 179 /* Conversion to and from GMP integer representations.  */
 180
 181 void mpz_set_double_int (mpz_t, double_int, bool);
 182 double_int mpz_get_double_int (const_tree, mpz_t, bool);
 183
 184
 185 #endif /* DOUBLE_INT_H */