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Annotation of 43BSD/contrib/X/hacks/bitrot/twiddle.h, revision 1.1.1.1

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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