[rustc.git] / src / libcompiler_builtins / compiler-rt / lib / builtins / clzti2.c

/* ===-- clzti2.c - Implement __clzti2 -------------------------------------===
 *
 *      	       The LLVM Compiler Infrastructure
 *
 * This file is dual licensed under the MIT and the University of Illinois Open
 * Source Licenses. See LICENSE.TXT for details.
 *
 * ===----------------------------------------------------------------------===
 *
 * This file implements __clzti2 for the compiler_rt library.
 *
 * ===----------------------------------------------------------------------===
 */

#include "int_lib.h"

#ifdef CRT_HAS_128BIT

/* Returns: the number of leading 0-bits */

/* Precondition: a != 0 */

COMPILER_RT_ABI si_int
__clzti2(ti_int a)
{
    twords x;
    x.all = a;
    const di_int f = -(x.s.high == 0);
    return __builtin_clzll((x.s.high & ~f) | (x.s.low & f)) +
           ((si_int)f & ((si_int)(sizeof(di_int) * CHAR_BIT)));
}

#endif /* CRT_HAS_128BIT */
Commit	Line	Data
1a4d82fc JJ	1	/* ===-- clzti2.c - Implement __clzti2 -------------------------------------===
	2	*
	3	* The LLVM Compiler Infrastructure
	4	*
	5	* This file is dual licensed under the MIT and the University of Illinois Open
	6	* Source Licenses. See LICENSE.TXT for details.
	7	*
	8	* ===----------------------------------------------------------------------===
	9	*
	10	* This file implements __clzti2 for the compiler_rt library.
	11	*
	12	* ===----------------------------------------------------------------------===
	13	*/
	14
	15	#include "int_lib.h"
	16
	17	#ifdef CRT_HAS_128BIT
	18
	19	/* Returns: the number of leading 0-bits */
	20
	21	/* Precondition: a != 0 */
	22
	23	COMPILER_RT_ABI si_int
	24	__clzti2(ti_int a)
	25	{
	26	twords x;
	27	x.all = a;
	28	const di_int f = -(x.s.high == 0);
	29	return __builtin_clzll((x.s.high & ~f) \| (x.s.low & f)) +
	30	((si_int)f & ((si_int)(sizeof(di_int) * CHAR_BIT)));
	31	}
	32
	33	#endif /* CRT_HAS_128BIT */