59 lines
962 B
C
59 lines
962 B
C
#include "f2c.h"
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#ifndef LONGBITS
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#define LONGBITS 32
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#endif
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integer
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lbit_bits (integer a, integer b, integer len)
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{
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/* Assume 2's complement arithmetic */
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unsigned long x, y;
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x = (unsigned long) a;
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y = (unsigned long) -1L;
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x >>= b;
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y <<= len;
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return (integer) (x & ~y);
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}
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integer
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lbit_cshift (integer a, integer b, integer len)
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{
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unsigned long x, y, z;
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x = (unsigned long) a;
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if (len <= 0)
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{
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if (len == 0)
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return 0;
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goto full_len;
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}
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if (len >= LONGBITS)
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{
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full_len:
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if (b >= 0)
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{
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b %= LONGBITS;
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return (integer) (x << b | x >> LONGBITS - b);
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}
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b = -b;
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b %= LONGBITS;
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return (integer) (x << LONGBITS - b | x >> b);
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}
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y = z = (unsigned long) -1;
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y <<= len;
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z &= ~y;
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y &= x;
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x &= z;
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if (b >= 0)
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{
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b %= len;
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return (integer) (y | z & (x << b | x >> len - b));
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}
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b = -b;
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b %= len;
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return (integer) (y | z & (x >> b | x << len - b));
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}
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