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//! Bit Manipulation Instruction (BMI) Set 1.0.
//!
//! The reference is [Intel 64 and IA-32 Architectures Software Developer's
//! Manual Volume 2: Instruction Set Reference, A-Z][intel64_ref].
//!
//! [Wikipedia][wikipedia_bmi] provides a quick overview of the instructions
//! available.
//!
//! [intel64_ref]: http://www.intel.de/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf
//! [wikipedia_bmi]: https://en.wikipedia.org/wiki/Bit_Manipulation_Instruction_Sets#ABM_.28Advanced_Bit_Manipulation.29
#[cfg(test)]
use stdarch_test::assert_instr;
/// Extracts bits in range [`start`, `start` + `length`) from `a` into
/// the least significant bits of the result.
///
/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_bextr_u32)
#[inline]
#[target_feature(enable = "bmi1")]
#[cfg_attr(test, assert_instr(bextr))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub unsafe fn _bextr_u32(a: u32, start: u32, len: u32) -> u32 {
_bextr2_u32(a, (start & 0xff_u32) | ((len & 0xff_u32) << 8_u32))
}
/// Extracts bits of `a` specified by `control` into
/// the least significant bits of the result.
///
/// Bits `[7,0]` of `control` specify the index to the first bit in the range
/// to be extracted, and bits `[15,8]` specify the length of the range.
///
/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_bextr2_u32)
#[inline]
#[target_feature(enable = "bmi1")]
#[cfg_attr(test, assert_instr(bextr))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub unsafe fn _bextr2_u32(a: u32, control: u32) -> u32 {
x86_bmi_bextr_32(a, control)
}
/// Bitwise logical `AND` of inverted `a` with `b`.
///
/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_andn_u32)
#[inline]
#[target_feature(enable = "bmi1")]
#[cfg_attr(test, assert_instr(andn))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub unsafe fn _andn_u32(a: u32, b: u32) -> u32 {
!a & b
}
/// Extracts lowest set isolated bit.
///
/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_blsi_u32)
#[inline]
#[target_feature(enable = "bmi1")]
#[cfg_attr(test, assert_instr(blsi))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub unsafe fn _blsi_u32(x: u32) -> u32 {
x & x.wrapping_neg()
}
/// Gets mask up to lowest set bit.
///
/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_blsmsk_u32)
#[inline]
#[target_feature(enable = "bmi1")]
#[cfg_attr(test, assert_instr(blsmsk))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub unsafe fn _blsmsk_u32(x: u32) -> u32 {
x ^ (x.wrapping_sub(1_u32))
}
/// Resets the lowest set bit of `x`.
///
/// If `x` is sets CF.
///
/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_blsr_u32)
#[inline]
#[target_feature(enable = "bmi1")]
#[cfg_attr(test, assert_instr(blsr))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub unsafe fn _blsr_u32(x: u32) -> u32 {
x & (x.wrapping_sub(1))
}
/// Counts the number of trailing least significant zero bits.
///
/// When the source operand is `0`, it returns its size in bits.
///
/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_tzcnt_u32)
#[inline]
#[target_feature(enable = "bmi1")]
#[cfg_attr(test, assert_instr(tzcnt))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub unsafe fn _tzcnt_u32(x: u32) -> u32 {
x.trailing_zeros()
}
/// Counts the number of trailing least significant zero bits.
///
/// When the source operand is `0`, it returns its size in bits.
///
/// [Intel's documentation](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_mm_tzcnt_32)
#[inline]
#[target_feature(enable = "bmi1")]
#[cfg_attr(test, assert_instr(tzcnt))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub unsafe fn _mm_tzcnt_32(x: u32) -> i32 {
x.trailing_zeros() as i32
}
extern "C" {
#[link_name = "llvm.x86.bmi.bextr.32"]
fn x86_bmi_bextr_32(x: u32, y: u32) -> u32;
}
#[cfg(test)]
mod tests {
use stdarch_test::simd_test;
use crate::core_arch::x86::*;
#[simd_test(enable = "bmi1")]
unsafe fn test_bextr_u32() {
let r = _bextr_u32(0b0101_0000u32, 4, 4);
assert_eq!(r, 0b0000_0101u32);
}
#[simd_test(enable = "bmi1")]
unsafe fn test_andn_u32() {
assert_eq!(_andn_u32(0, 0), 0);
assert_eq!(_andn_u32(0, 1), 1);
assert_eq!(_andn_u32(1, 0), 0);
assert_eq!(_andn_u32(1, 1), 0);
let r = _andn_u32(0b0000_0000u32, 0b0000_0000u32);
assert_eq!(r, 0b0000_0000u32);
let r = _andn_u32(0b0000_0000u32, 0b1111_1111u32);
assert_eq!(r, 0b1111_1111u32);
let r = _andn_u32(0b1111_1111u32, 0b0000_0000u32);
assert_eq!(r, 0b0000_0000u32);
let r = _andn_u32(0b1111_1111u32, 0b1111_1111u32);
assert_eq!(r, 0b0000_0000u32);
let r = _andn_u32(0b0100_0000u32, 0b0101_1101u32);
assert_eq!(r, 0b0001_1101u32);
}
#[simd_test(enable = "bmi1")]
unsafe fn test_blsi_u32() {
assert_eq!(_blsi_u32(0b1101_0000u32), 0b0001_0000u32);
}
#[simd_test(enable = "bmi1")]
unsafe fn test_blsmsk_u32() {
let r = _blsmsk_u32(0b0011_0000u32);
assert_eq!(r, 0b0001_1111u32);
}
#[simd_test(enable = "bmi1")]
unsafe fn test_blsr_u32() {
// TODO: test the behavior when the input is `0`.
let r = _blsr_u32(0b0011_0000u32);
assert_eq!(r, 0b0010_0000u32);
}
#[simd_test(enable = "bmi1")]
unsafe fn test_tzcnt_u32() {
assert_eq!(_tzcnt_u32(0b0000_0001u32), 0u32);
assert_eq!(_tzcnt_u32(0b0000_0000u32), 32u32);
assert_eq!(_tzcnt_u32(0b1001_0000u32), 4u32);
}
}
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