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Annotation of 43BSDTahoe/new/X/hacks/bitrot/twiddle.h, revision 1.1

1.1     ! root        1: /*
        !             2:  *     $Source: /u1/X/hacks/bitrot/RCS/twiddle.h,v $
        !             3:  *     $Author: tony $
        !             4:  *     $Locker:  $
        !             5:  *     $Header: twiddle.h,v 10.1 86/02/01 15:43:23 tony Rel $
        !             6:  */
        !             7: 
        !             8: #include <sys/types.h>
        !             9: 
        !            10: /* WARNING!  ASSUMES 8-BIT CHARACTERS! */
        !            11: 
        !            12: /* Each of these operates on the xth bit from map */
        !            13: /* Map must be a pointer, not necessarily a u_char pointer */
        !            14: #define fetch(map, x) (1 & (((u_char *) map)[x >> 3] >> (x & 7)))
        !            15: #define set(map, x) ((((u_char *) map)[x>>3] |= 1 << (x & 7)))
        !            16: #define reset(map, x) ((((u_char *) map)[x>>3] &= ~(1 << (x & 7))))
        !            17: #define flip(map,x) ((((u_char *) map)[x>>3] ^=  1 << (x & 7)))
        !            18: #define place(map, x, bit) ((bit ? set(map,x),0 : reset(map,x), 0))

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