?? bitstr.c
字號:
/*
file : bitstr.c
author : Erik Mavrinac
version : 1.10
description: These routines manipulate bits in an unsigned int array, to
facilitate efficient true-false/boolean arrays. Originally an idea in
Computer Language magazine (April, 1989, pages 34-43), I have made very ex-
tensive modifications. These routines may or may not only be able to be
used on i80x86-- I have no way to try portability experiments.
*/
#include "bitstr.h"
/* size of unsigned int in bits */
#define US 16
void clear_bit(unsigned *string, int bit)
/* sets the "bit" bit to 0 */
{
*(string+bit/US) &= (~(HEX1 << (US-1-(bit % US))));
}
void set_bit(unsigned *string, int bit)
/* sets the "bit" bit to 1 */
{
*(string+bit/US) |= (HEX1 << (US-1-(bit % US)));
}
int test_bit(unsigned *string, int bit)
/* returns non-zero if "bit" is set */
{
return (*(string+bit/US) & (HEX1 << (US-1-(bit % US))));
}
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