bitops(3) [netbsd man page]

BITOPS(3)						   BSD Library Functions Manual 						 BITOPS(3)

NAME

     bitops -- functions related to bits and integers

SYNOPSIS

     #include <sys/bitops.h>

DESCRIPTION

     The <sys/bitops.h> header includes some static inline functions related bits and integers.  Among these are:

	   ffs32(3)	      functions to find the first and last bit in integers of type uint32_t and uint64_t

	   ilog2(3)	      a macro for binary logarithm

	   fast_divide32(3)   a function for fast 32-bit division

SEE ALSO

     bits(3), bitstring(3), cdefs(3), param(3)

HISTORY

     The <sys/bitops.h> header first appeared in NetBSD 4.0.

BSD
								   April 8, 2011							       BSD

FFS32(3)						   BSD Library Functions Manual 						  FFS32(3)

NAME

     ffs32, ffs64, fls32, fls64 -- find first or last bit set

SYNOPSIS

     #include <sys/bitops.h>

     int
     ffs32(uint32_t n);

     int
     ffs64(uint64_t n);

     int
     fls32(uint32_t n);

     int
     fls64(uint64_t n);

DESCRIPTION

     The ffs32() and ffs64() functions find the first bit set in n and return the index of that bit.  Conversely, the fls32() and fls64() func-
     tions find the last bit set in n, returning the index of the bit.

     The search always starts from the bit 1 (the least significant bit).  If the argument n is zero, each function returns zero.

IMPLEMENTATION NOTES

     The described functions are implemented as static inline functions in the <sys/bitops.h> header.  The standard C library includes a more por-
     table ffs(3) for user applications.

EXAMPLES

     In the following example f = 3 and l = 7:

	   uint32_t n = 0x44;	   /* 01000100 */
	   int f, l;

	   f = ffs32(n);
	   l = fls32(n);

SEE ALSO

     bitops(3), bits(3), bitstring(3), ffs(3), setbit(9)

HISTORY

     These functions first appeared in NetBSD 5.0.

BSD
								   April 8, 2011							       BSD