libf2c/libF77/lbitbits.c

   1 #include "f2c.h"
   2
   3 #ifndef LONGBITS
   4 #define LONGBITS 32
   5 #endif
   6
   7 integer
   8 lbit_bits (integer a, integer b, integer len)
   9 {
  10   /* Assume 2's complement arithmetic */
  11
  12   unsigned long x, y;
  13
  14   x = (unsigned long) a;
  15   y = (unsigned long) -1L;
  16   x >>= b;
  17   y <<= len;
  18   return (integer) (x & ~y);
  19 }
  20
  21 integer
  22 lbit_cshift (integer a, integer b, integer len)
  23 {
  24   unsigned long x, y, z;
  25
  26   x = (unsigned long) a;
  27   if (len <= 0)
  28     {
  29       if (len == 0)
  30         return 0;
  31       goto full_len;
  32     }
  33   if (len >= LONGBITS)
  34     {
  35     full_len:
  36       if (b >= 0)
  37         {
  38           b %= LONGBITS;
  39           return (integer) (x << b | x >> (LONGBITS - b));
  40         }
  41       b = -b;
  42       b %= LONGBITS;
  43       return (integer) (x << (LONGBITS - b) | x >> b);
  44     }
  45   y = z = (unsigned long) -1;
  46   y <<= len;
  47   z &= ~y;
  48   y &= x;
  49   x &= z;
  50   if (b >= 0)
  51     {
  52       b %= len;
  53       return (integer) (y | (z & (x << b | x >> (len - b))));
  54     }
  55   b = -b;
  56   b %= len;
  57   return (integer) (y | (z & (x >> b | x << (len - b))));
  58 }