Dogcows Code - chaz/tar/blob - src/arith.h

   1 /* Simple arithmetic for numbers greater than a long int, for GNU tar.
   2    Copyright (C) 1996, 1997 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Also, see comments at beginning of arith.c.  */
  19
  20 #define BITS_PER_BYTE 8         /* number of bits in each sizeof unit */
  21 #define BITS_PER_TARLONG 42     /* wanted number of bits in each tarlong */
  22
  23 /* In all cases, tarlong is the proper type for a big number.
  24
  25    For simulated arithmetic, SUPERDIGIT is the base, TARLONG_FORMAT is the
  26    format to print a single super-digit filled with zeroes to the left, and
  27    BITS_PER_SUPERDIGIT is the smallest number of bits required to fully
  28    represent each super-digit.  LONGS_PER_TARLONG says how many longs are
  29    required for a full tarlong, and SIZEOF_TARLONG is the size of a tarlong
  30    in bytes.
  31
  32    For straight compiler arithmetic, SUPERDIGIT is zero and TARLONG_FORMAT
  33    is the format to directly print a tarlong (without zero-filling).
  34
  35    The values of SIZEOF_LONG_LONG and SIZEOF_UNSIGNED_LONG, below, are
  36    obtained through the configuration process.  */
  37
  38 #if BITS_PER_BYTE * SIZEOF_UNSIGNED_LONG >= BITS_PER_TARLONG
  39 # define SUPERDIGIT 0
  40 # define TARLONG_FORMAT "%uld"
  41 typedef unsigned long tarlong;
  42 #else
  43 # if BITS_PER_BYTE * SIZEOF_LONG_LONG >= BITS_PER_TARLONG + 1
  44 #  define SUPERDIGIT 0
  45 #  define TARLONG_FORMAT "%lld"
  46 typedef long long tarlong;
  47 # else
  48 #  if BITS_PER_BYTE * SIZEOF_UNSIGNED_LONG >= 64
  49 #   define SUPERDIGIT 1000000000L
  50 #   define BITS_PER_SUPERDIGIT 29
  51 #   define TARLONG_FORMAT "%09uld"
  52 #  else
  53 #   if BITS_PER_BYTE * SIZEOF_UNSIGNED_LONG >= 32
  54 #    define SUPERDIGIT 10000L
  55 #    define BITS_PER_SUPERDIGIT 14
  56 #    define TARLONG_FORMAT "%04uld"
  57 #   endif
  58 #  endif
  59 # endif
  60 #endif
  61
  62 #if SUPERDIGIT
  63
  64 # define LONGS_PER_TARLONG \
  65     ((BITS_PER_TARLONG + BITS_PER_SUPERDIGIT - 1) / BITS_PER_SUPERDIGIT)
  66 # define SIZEOF_TARLONG (LONGS_PER_TARLONG * sizeof (unsigned long))
  67
  68 /* The NEC EWS 4.2 C compiler gets confused by a pointer to a typedef that
  69    is an array.  So we wrap the array into a struct.  (Pouah!)  */
  70
  71 struct tarlong
  72 {
  73   unsigned long digit[LONGS_PER_TARLONG];
  74 };
  75
  76 typedef struct tarlong tarlong;
  77
  78 int zerop_tarlong_helper PARAMS ((unsigned long *));
  79 int lessp_tarlong_helper PARAMS ((unsigned long *, unsigned long *));
  80 void clear_tarlong_helper PARAMS ((unsigned long *));
  81 void add_to_tarlong_helper PARAMS ((unsigned long *, int));
  82 void mult_tarlong_helper PARAMS ((unsigned long *, int));
  83 void print_tarlong_helper PARAMS ((unsigned long *, FILE *));
  84
  85 # define zerop_tarlong(Accumulator) \
  86    zerop_tarlong_helper (&(Accumulator).digit[0])
  87
  88 # define lessp_tarlong(First, Second) \
  89    lessp_tarlong_helper (&(First).digit[0], &(Second).digit[0])
  90
  91 # define clear_tarlong(Accumulator) \
  92    clear_tarlong_helper (&(Accumulator).digit[0])
  93
  94 # define add_to_tarlong(Accumulator, Value) \
  95    add_to_tarlong_helper (&(Accumulator).digit[0], (Value))
  96
  97 # define mult_tarlong(Accumulator, Value) \
  98    mult_tarlong_helper (&(Accumulator).digit[0], (Value))
  99
 100 # define print_tarlong(Accumulator, File) \
 101    print_tarlong_helper (&(Accumulator).digit[0], (File))
 102
 103 #else /* not SUPERDIGIT */
 104
 105 # define zerop_tarlong(Accumulator) \
 106    ((Accumulator) == 0)
 107
 108 # define lessp_tarlong(First, Second) \
 109    ((First) < (Second))
 110
 111 # define clear_tarlong(Accumulator) \
 112    ((Accumulator) = 0)
 113
 114 # define add_to_tarlong(Accumulator, Value) \
 115    ((Accumulator) += (Value))
 116
 117 # define mult_tarlong(Accumulator, Value) \
 118    ((Accumulator) *= (Value))
 119
 120 # define print_tarlong(Accumulator, File) \
 121    (fprintf ((File), TARLONG_FORMAT, (Accumulator)))
 122
 123 #endif /* not SUPERDIGIT */