Commit 3c6a0755 authored by Rémi Denis-Courmont's avatar Rémi Denis-Courmont
Browse files

clz: count leading zeroes

parent 44c71045
......@@ -621,6 +621,29 @@ static inline uint8_t clip_uint8_vlc( int32_t a )
else return a;
}
/* Count leading zeroes */
LIBVLC_USED
static inline unsigned clz (unsigned x)
{
#ifdef __GNUC_
return __builtin_clz (x);
#else
unsigned i = sizeof (x) * 8;
while (x)
{
x = x >> 1;
i--;
}
return i;
#endif
}
#define clz8( x ) (clz(x) - ((sizeof(unsigned) - sizeof (uint8_t)) * 8))
#define clz16( x ) (clz(x) - ((sizeof(unsigned) - sizeof (uint16_t)) * 8))
/* XXX: this assumes that int is 32-bits or more */
#define clz32( x ) (clz(x) - ((sizeof(unsigned) - sizeof (uint32_t)) * 8))
/* Free and set set the variable to NULL */
#define FREENULL(a) do { free( a ); a = NULL; } while(0)
......
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