lbitbits.c

来自「DTMK软件开发包,此为开源软件,是一款很好的医学图像开发资源.」· C语言 代码 · 共 69 行

#include "v3p_f2c.h"
#ifdef __cplusplus
extern "C" {
#endif

#ifndef LONGBITS
#define LONGBITS 32
#endif

 integer
#ifdef KR_headers
lbit_bits(a, b, len) integer a, b, len;
#else
lbit_bits(integer a, integer b, integer len)
#endif
{
        /* Assume 2's complement arithmetic */

        unsigned long x, y;

        x = (unsigned long) a;
        y = (unsigned long)-1L;
        x >>= b;
        y <<= len;
        return (integer)(x & ~y);
        }

 integer
#ifdef KR_headers
lbit_cshift(a, b, len) integer a, b, len;
#else
lbit_cshift(integer a, integer b, integer len)
#endif
{
        unsigned long x, y, z;

        x = (unsigned long)a;
        if (len <= 0) {
                if (len == 0)
                        return 0;
                goto full_len;
                }
        if (len >= LONGBITS) {
 full_len:
                if (b >= 0) {
                        b %= LONGBITS;
                        return (integer)(x << b | x >> LONGBITS -b );
                        }
                b = -b;
                b %= LONGBITS;
                return (integer)(x << LONGBITS - b | x >> b);
                }
        y = z = (unsigned long)-1;
        y <<= len;
        z &= ~y;
        y &= x;
        x &= z;
        if (b >= 0) {
                b %= len;
                return (integer)(y | z & (x << b | x >> len - b));
                }
        b = -b;
        b %= len;
        return (integer)(y | z & (x >> b | x << len - b));
        }
#ifdef __cplusplus
}
#endif