src/common/bits.cpp

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/***********************************************************
*PANALIX 0.06, (c) Adrian Panasiuk 2002-4                  *
*adek336[at]o2.pl, panalix.prv.pl                          *
*under GPLv3 license                                       *
*                                                          *
*panalix - small osdev project                             *
************************************************************
*       bits.cpp, version 1.1                              *
************************************************************
*                                                          *
*primitive and naive bit operations, not very optimised.   *
*                                                          *
*03'05'04- forked from o.05 branch.s bits.cpp(1.0)         *
*                                                          *
***********************************************************/

#include "src/common/shared.hpp"
#include "src/common/bits.hpp"

//returns the value of bit (which) in (n)
char bit_val(char n, char which)
 {
char x;
        /*the chosen bit is now 1*/
        x = 1 << which;

        /*use the mask*/
        return (n & x) >> which;
 }

//returns (n) with bit (which) set to (what).
char bit_set(char n, char which, char what)
 {
        /*bit (which) = (what), all other bits = 0*/
        what = what << which;

        /*mask excluding bit (which)*/
        which = 0xFF - (1 << which);

        /*masked n*/
        n = n & which;

        return n + what;
 }

//changes bit (which) in (*n) to (what). returns the value
char bit_ptr(char *n, char which, char what)
 {
char x;
        x = bit_set(*n, which, what);
        *n = x;
        return x;
 }

/*****************************************************
*
*panalix 0.04 (c) Adrian Panasiuk 2003
*adek336[at]o2.pl, panalix.prv.pl
*
*****************************************************/

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