bt.rs.html -- source
Description: Source to the Rust file `src\libcore\..\stdarch\crates\core_arch\src\x86\bt.rs`.
Keywords: rust, rustlang, rust-lang

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    #[cfg(test)]
    use stdarch_test::assert_instr;

    /// Returns the bit in position `b` of the memory addressed by `p`.
    #[inline]
    #[cfg_attr(test, assert_instr(bt))]
    #[unstable(feature = "simd_x86_bittest", issue = "59414")]
    pub unsafe fn _bittest(p: *const i32, b: i32) -> u8 {
        let r: u8;
        asm!("btl $2, $1\n\tsetc ${0:b}"
             : "=r"(r)
             : "*m"(p), "r"(b)
             : "cc", "memory");
        r
    }

    /// Returns the bit in position `b` of the memory addressed by `p`, then sets the bit to `1`.
    #[inline]
    #[cfg_attr(test, assert_instr(bts))]
    #[unstable(feature = "simd_x86_bittest", issue = "59414")]
    pub unsafe fn _bittestandset(p: *mut i32, b: i32) -> u8 {
        let r: u8;
        asm!("btsl $2, $1\n\tsetc ${0:b}"
             : "=r"(r), "+*m"(p)
             : "r"(b)
             : "cc", "memory");
        r
    }

    /// Returns the bit in position `b` of the memory addressed by `p`, then resets that bit to `0`.
    #[inline]
    #[cfg_attr(test, assert_instr(btr))]
    #[unstable(feature = "simd_x86_bittest", issue = "59414")]
    pub unsafe fn _bittestandreset(p: *mut i32, b: i32) -> u8 {
        let r: u8;
        asm!("btrl $2, $1\n\tsetc ${0:b}"
             : "=r"(r), "+*m"(p)
             : "r"(b)
             : "cc", "memory");
        r
    }

    /// Returns the bit in position `b` of the memory addressed by `p`, then inverts that bit.
    #[inline]
    #[cfg_attr(test, assert_instr(btc))]
    #[unstable(feature = "simd_x86_bittest", issue = "59414")]
    pub unsafe fn _bittestandcomplement(p: *mut i32, b: i32) -> u8 {
        let r: u8;
        asm!("btcl $2, $1\n\tsetc ${0:b}"
             : "=r"(r), "+*m"(p)
             : "r"(b)
             : "cc", "memory");
        r
    }

    #[cfg(test)]
    mod tests {
        use crate::core_arch::x86::*;

        #[test]
        fn test_bittest() {
            unsafe {
                let a = 0b0101_0000i32;
                assert_eq!(_bittest(&a as _, 4), 1);
                assert_eq!(_bittest(&a as _, 5), 0);
            }
        }

        #[test]
        fn test_bittestandset() {
            unsafe {
                let mut a = 0b0101_0000i32;
                assert_eq!(_bittestandset(&mut a as _, 4), 1);
                assert_eq!(_bittestandset(&mut a as _, 4), 1);
                assert_eq!(_bittestandset(&mut a as _, 5), 0);
                assert_eq!(_bittestandset(&mut a as _, 5), 1);
            }
        }

        #[test]
        fn test_bittestandreset() {
            unsafe {
                let mut a = 0b0101_0000i32;
                assert_eq!(_bittestandreset(&mut a as _, 4), 1);
                assert_eq!(_bittestandreset(&mut a as _, 4), 0);
                assert_eq!(_bittestandreset(&mut a as _, 5), 0);
                assert_eq!(_bittestandreset(&mut a as _, 5), 0);
            }
        }

        #[test]
        fn test_bittestandcomplement() {
            unsafe {
                let mut a = 0b0101_0000i32;
                assert_eq!(_bittestandcomplement(&mut a as _, 4), 1);
                assert_eq!(_bittestandcomplement(&mut a as _, 4), 0);
                assert_eq!(_bittestandcomplement(&mut a as _, 4), 1);
                assert_eq!(_bittestandcomplement(&mut a as _, 5), 0);
                assert_eq!(_bittestandcomplement(&mut a as _, 5), 1);
            }
        }
    }