v8.rs.html -- source
Description: Source to the Rust file `src/libcore/../stdsimd/crates/core_arch/src/aarch64/v8.rs`.
Keywords: rust, rustlang, rust-lang

      1
      2
      3
      4
      5
      6
      7
      8
      9
     10
     11
     12
     13
     14
     15
     16
     17
     18
     19
     20
     21
     22
     23
     24
     25
     26
     27
     28
     29
     30
     31
     32
     33
     34
     35
     36
     37
     38
     39
     40
     41
     42
     43
     44
     45
     46
     47
     48
     49
     50
     51
     52
     53
     54
     55
     56
     57
     58
     59
     60
     61
     62
     63
     64
     65
     66
     67
     68
     69
     70
     71
     72
     73
     74
     75
     76
     77
     78
     79
     80
     81
     82
     83
     84
     85
     86
     87
     88
     89
     90
     91
     92
     93
     94
     95
     96
     97
     98
     99
    100
    101
    102
    103
    104

    //! ARMv8 intrinsics.
    //!
    //! The reference is [ARMv8-A Reference Manual][armv8].
    //!
    //! [armv8]: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.
    //! ddi0487a.k_10775/index.html

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

    /// Reverse the order of the bytes.
    #[inline]
    #[cfg_attr(test, assert_instr(rev))]
    pub unsafe fn _rev_u64(x: u64) -> u64 {
        x.swap_bytes() as u64
    }

    /// Count Leading Zeros.
    #[inline]
    #[cfg_attr(test, assert_instr(clz))]
    pub unsafe fn _clz_u64(x: u64) -> u64 {
        x.leading_zeros() as u64
    }

    /// Reverse the bit order.
    #[inline]
    #[cfg_attr(test, assert_instr(rbit))]
    pub unsafe fn _rbit_u64(x: u64) -> u64 {
        crate::intrinsics::bitreverse(x)
    }

    /// Counts the leading most significant bits set.
    ///
    /// When all bits of the operand are set it returns the size of the operand in
    /// bits.
    #[inline]
    #[cfg_attr(test, assert_instr(cls))]
    pub unsafe fn _cls_u32(x: u32) -> u32 {
        u32::leading_zeros((((((x as i32) >> 31) as u32) ^ x) << 1) | 1) as u32
    }

    /// Counts the leading most significant bits set.
    ///
    /// When all bits of the operand are set it returns the size of the operand in
    /// bits.
    #[inline]
    #[cfg_attr(test, assert_instr(cls))]
    pub unsafe fn _cls_u64(x: u64) -> u64 {
        u64::leading_zeros((((((x as i64) >> 63) as u64) ^ x) << 1) | 1) as u64
    }

    #[cfg(test)]
    mod tests {
        use crate::core_arch::aarch64::v8;

        #[test]
        fn _rev_u64() {
            unsafe {
                assert_eq!(
                    v8::_rev_u64(0b0000_0000_1111_1111_0000_0000_1111_1111_u64),
                    0b1111_1111_0000_0000_1111_1111_0000_0000_0000_0000_0000_0000_0000_0000_0000_0000_u64
                );
            }
        }

        #[test]
        fn _clz_u64() {
            unsafe {
                assert_eq!(v8::_clz_u64(0b0000_1010u64), 60u64);
            }
        }

        #[test]
        fn _rbit_u64() {
            unsafe {
                assert_eq!(
                    v8::_rbit_u64(0b0000_0000_1111_1101_0000_0000_1111_1111_u64),
                    0b1111_1111_0000_0000_1011_1111_0000_0000_0000_0000_0000_0000_0000_0000_0000_0000_u64
                );
            }
        }

        #[test]
        fn _cls_u32() {
            unsafe {
                assert_eq!(
                    v8::_cls_u32(0b1111_1111_1111_1111_0000_0000_1111_1111_u32),
                    15_u32
                );
            }
        }

        #[test]
        fn _cls_u64() {
            unsafe {
                assert_eq!(
                    v8::_cls_u64(
                        0b1111_1111_1111_1111_0000_0000_1111_1111_0000_0000_0000_0000_0000_0000_0000_0000_u64
                    ),
                    15_u64
                );
            }
        }
    }

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g., `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g., `vec -> usize` or `* -> vec`)

Search multiple things at once by splitting your query with comma (e.g., `str,u8` or `String,struct:Vec,test`)