1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // ignore-fast #[feature] doesn't work with check-fast
14 #[cfg(target_arch = "x86")]
15 #[cfg(target_arch = "x86_64")]
16 unsafe fn next_power_of_2(n: u32) -> u32 {
18 asm!("dec $0" : "+rm"(tmp) :: "cc");
25 : "+&rm"(tmp), "+{ecx}"(shift) : "r"(tmp) : "cc"
28 asm!("inc $0" : "+rm"(tmp) :: "cc");
32 #[cfg(target_arch = "x86")]
33 #[cfg(target_arch = "x86_64")]
36 assert_eq!(64, next_power_of_2(37));
37 assert_eq!(2147483648, next_power_of_2(2147483647));
43 // Treat the output as initialization.
48 : "=r"(x), "+r"(y) : "i"(3u), "ir"(7u) : "cc"
58 // Assignment to mutable.
60 // Forbids the use of a single register by both operands.
61 asm!("shr $$2, $1; add $1, $0" : "+&r"(x) : "r"(x) : "cc");
66 #[cfg(not(target_arch = "x86"), not(target_arch = "x86_64"))]