| FFS32(3) | Library Functions Manual | FFS32(3) | 
ffs32, ffs64,
  fls32, fls64 —
#include <sys/bitops.h>
int
  
  ffs32(uint32_t
    n);
int
  
  ffs64(uint64_t
    n);
int
  
  fls32(uint32_t
    n);
int
  
  fls64(uint64_t
    n);
ffs32() and ffs64()
  functions find the first bit set in n and return the
  index of that bit. Conversely, the fls32() and
  fls64() functions 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.
<sys/bitops.h> header. The
  standard C library includes a more portable
  ffs(3) for user applications.
uint32_t n = 0x44; /* 01000100 */ int f, l; f = ffs32(n); l = fls32(n);
| April 8, 2011 | NetBSD 9.4 |