pub trait SelectInWord: core::ops::Not<Output = Self> + Sized + Copy {
fn select_in_word(&self, rank: usize) -> usize;
#[inline(always)]
fn select_zero_in_word(&self, rank: usize) -> usize {
(!*self).select_in_word(rank)
}
}
impl SelectInWord for u8 {
#[inline(always)]
fn select_in_word(&self, rank: usize) -> usize {
debug_assert!(rank < self.count_ones() as _);
let index = *self as usize | (rank << 8);
SELECT_IN_BYTE[index] as usize
}
}
#[cfg(not(target_feature = "bmi2"))]
macro_rules! popcount_check_byte {
($bytes:expr, $remaining:ident, $idx:expr) => {
let ones = POPCOUNT[$bytes[$idx] as usize] as usize;
if $remaining < ones {
return $idx * 8 + SELECT_IN_BYTE[$bytes[$idx] as usize | ($remaining << 8)] as usize;
}
$remaining -= ones;
};
}
#[cfg(not(target_feature = "bmi2"))]
const POPCOUNT: [u8; 256] = [
0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
];
impl SelectInWord for u16 {
#[inline(always)]
fn select_in_word(&self, rank: usize) -> usize {
debug_assert!(rank < self.count_ones() as _);
#[cfg(target_feature = "bmi2")]
{
(*self as u32).select_in_word(rank)
}
#[cfg(not(target_feature = "bmi2"))]
{
let bytes = self.to_le_bytes();
let mut remaining = rank;
popcount_check_byte!(bytes, remaining, 0);
8 + SELECT_IN_BYTE[bytes[1] as usize | (remaining << 8)] as usize
}
}
}
impl SelectInWord for u32 {
#[inline(always)]
fn select_in_word(&self, rank: usize) -> usize {
debug_assert!(rank < self.count_ones() as _);
#[cfg(target_feature = "bmi2")]
{
#[cfg(target_arch = "x86")]
use core::arch::x86::_pdep_u32;
#[cfg(target_arch = "x86_64")]
use core::arch::x86_64::_pdep_u32;
let mask = 1 << rank;
let one = unsafe { _pdep_u32(mask, *self) };
one.trailing_zeros() as usize
}
#[cfg(not(target_feature = "bmi2"))]
{
let bytes = self.to_le_bytes();
let mut remaining = rank;
popcount_check_byte!(bytes, remaining, 0);
popcount_check_byte!(bytes, remaining, 1);
popcount_check_byte!(bytes, remaining, 2);
24 + SELECT_IN_BYTE[bytes[3] as usize | (remaining << 8)] as usize
}
}
}
impl SelectInWord for u64 {
#[inline(always)]
fn select_in_word(&self, rank: usize) -> usize {
debug_assert!(rank < self.count_ones() as _);
#[cfg(all(target_feature = "bmi2", target_arch = "x86_64"))]
{
use core::arch::x86_64::_pdep_u64;
let mask = 1 << rank;
let one = unsafe { _pdep_u64(mask, *self) };
one.trailing_zeros() as usize
}
#[cfg(all(target_feature = "bmi2", not(target_arch = "x86_64")))]
{
let lower_ones = (*self as u32).count_ones() as usize;
if rank < lower_ones {
(*self as u32).select_in_word(rank)
} else {
32 + ((*self >> 32) as u32).select_in_word(rank - lower_ones)
}
}
#[cfg(not(target_feature = "bmi2"))]
{
let bytes = self.to_le_bytes();
let lower_ones = (*self as u32).count_ones() as usize;
if rank < lower_ones {
let mut remaining = rank;
popcount_check_byte!(bytes, remaining, 0);
popcount_check_byte!(bytes, remaining, 1);
popcount_check_byte!(bytes, remaining, 2);
24 + SELECT_IN_BYTE[bytes[3] as usize | (remaining << 8)] as usize
} else {
let mut remaining = rank - lower_ones;
popcount_check_byte!(bytes, remaining, 4);
popcount_check_byte!(bytes, remaining, 5);
popcount_check_byte!(bytes, remaining, 6);
56 + SELECT_IN_BYTE[bytes[7] as usize | (remaining << 8)] as usize
}
}
}
}
impl SelectInWord for u128 {
#[inline(always)]
fn select_in_word(&self, rank: usize) -> usize {
debug_assert!(rank < self.count_ones() as _);
#[cfg(target_feature = "bmi2")]
{
let ones = (*self as u64).count_ones() as usize;
if ones > rank {
(*self as u64).select_in_word(rank)
} else {
64 + ((*self >> 64) as u64).select_in_word(rank - ones)
}
}
#[cfg(not(target_feature = "bmi2"))]
{
let bytes = self.to_le_bytes();
let lower_ones = (*self as u64).count_ones() as usize;
if rank < lower_ones {
let lower_lower_ones = (*self as u32).count_ones() as usize;
if rank < lower_lower_ones {
let mut remaining = rank;
popcount_check_byte!(bytes, remaining, 0);
popcount_check_byte!(bytes, remaining, 1);
popcount_check_byte!(bytes, remaining, 2);
24 + SELECT_IN_BYTE[bytes[3] as usize | (remaining << 8)] as usize
} else {
let mut remaining = rank - lower_lower_ones;
popcount_check_byte!(bytes, remaining, 4);
popcount_check_byte!(bytes, remaining, 5);
popcount_check_byte!(bytes, remaining, 6);
56 + SELECT_IN_BYTE[bytes[7] as usize | (remaining << 8)] as usize
}
} else {
let upper = (*self >> 64) as u64;
let upper_lower_ones = (upper as u32).count_ones() as usize;
let remaining_in_upper = rank - lower_ones;
if remaining_in_upper < upper_lower_ones {
let mut remaining = remaining_in_upper;
popcount_check_byte!(bytes, remaining, 8);
popcount_check_byte!(bytes, remaining, 9);
popcount_check_byte!(bytes, remaining, 10);
88 + SELECT_IN_BYTE[bytes[11] as usize | (remaining << 8)] as usize
} else {
let mut remaining = remaining_in_upper - upper_lower_ones;
popcount_check_byte!(bytes, remaining, 12);
popcount_check_byte!(bytes, remaining, 13);
popcount_check_byte!(bytes, remaining, 14);
120 + SELECT_IN_BYTE[bytes[15] as usize | (remaining << 8)] as usize
}
}
}
}
}
#[cfg(target_pointer_width = "16")]
type Usize = u16;
#[cfg(target_pointer_width = "32")]
type Usize = u32;
#[cfg(target_pointer_width = "64")]
type Usize = u64;
impl SelectInWord for usize {
#[inline(always)]
fn select_in_word(&self, rank: usize) -> usize {
(*self as Usize).select_in_word(rank)
}
}
#[allow(clippy::all)]
const SELECT_IN_BYTE: [u8; 2048] = [
8, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
8, 8, 8, 1, 8, 2, 2, 1, 8, 3, 3, 1, 3, 2, 2, 1, 8, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
8, 5, 5, 1, 5, 2, 2, 1, 5, 3, 3, 1, 3, 2, 2, 1, 5, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
8, 6, 6, 1, 6, 2, 2, 1, 6, 3, 3, 1, 3, 2, 2, 1, 6, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
6, 5, 5, 1, 5, 2, 2, 1, 5, 3, 3, 1, 3, 2, 2, 1, 5, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
8, 7, 7, 1, 7, 2, 2, 1, 7, 3, 3, 1, 3, 2, 2, 1, 7, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
7, 5, 5, 1, 5, 2, 2, 1, 5, 3, 3, 1, 3, 2, 2, 1, 5, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
7, 6, 6, 1, 6, 2, 2, 1, 6, 3, 3, 1, 3, 2, 2, 1, 6, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
6, 5, 5, 1, 5, 2, 2, 1, 5, 3, 3, 1, 3, 2, 2, 1, 5, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
8, 8, 8, 8, 8, 8, 8, 2, 8, 8, 8, 3, 8, 3, 3, 2, 8, 8, 8, 4, 8, 4, 4, 2, 8, 4, 4, 3, 4, 3, 3, 2,
8, 8, 8, 5, 8, 5, 5, 2, 8, 5, 5, 3, 5, 3, 3, 2, 8, 5, 5, 4, 5, 4, 4, 2, 5, 4, 4, 3, 4, 3, 3, 2,
8, 8, 8, 6, 8, 6, 6, 2, 8, 6, 6, 3, 6, 3, 3, 2, 8, 6, 6, 4, 6, 4, 4, 2, 6, 4, 4, 3, 4, 3, 3, 2,
8, 6, 6, 5, 6, 5, 5, 2, 6, 5, 5, 3, 5, 3, 3, 2, 6, 5, 5, 4, 5, 4, 4, 2, 5, 4, 4, 3, 4, 3, 3, 2,
8, 8, 8, 7, 8, 7, 7, 2, 8, 7, 7, 3, 7, 3, 3, 2, 8, 7, 7, 4, 7, 4, 4, 2, 7, 4, 4, 3, 4, 3, 3, 2,
8, 7, 7, 5, 7, 5, 5, 2, 7, 5, 5, 3, 5, 3, 3, 2, 7, 5, 5, 4, 5, 4, 4, 2, 5, 4, 4, 3, 4, 3, 3, 2,
8, 7, 7, 6, 7, 6, 6, 2, 7, 6, 6, 3, 6, 3, 3, 2, 7, 6, 6, 4, 6, 4, 4, 2, 6, 4, 4, 3, 4, 3, 3, 2,
7, 6, 6, 5, 6, 5, 5, 2, 6, 5, 5, 3, 5, 3, 3, 2, 6, 5, 5, 4, 5, 4, 4, 2, 5, 4, 4, 3, 4, 3, 3, 2,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 3, 8, 8, 8, 8, 8, 8, 8, 4, 8, 8, 8, 4, 8, 4, 4, 3,
8, 8, 8, 8, 8, 8, 8, 5, 8, 8, 8, 5, 8, 5, 5, 3, 8, 8, 8, 5, 8, 5, 5, 4, 8, 5, 5, 4, 5, 4, 4, 3,
8, 8, 8, 8, 8, 8, 8, 6, 8, 8, 8, 6, 8, 6, 6, 3, 8, 8, 8, 6, 8, 6, 6, 4, 8, 6, 6, 4, 6, 4, 4, 3,
8, 8, 8, 6, 8, 6, 6, 5, 8, 6, 6, 5, 6, 5, 5, 3, 8, 6, 6, 5, 6, 5, 5, 4, 6, 5, 5, 4, 5, 4, 4, 3,
8, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 7, 8, 7, 7, 3, 8, 8, 8, 7, 8, 7, 7, 4, 8, 7, 7, 4, 7, 4, 4, 3,
8, 8, 8, 7, 8, 7, 7, 5, 8, 7, 7, 5, 7, 5, 5, 3, 8, 7, 7, 5, 7, 5, 5, 4, 7, 5, 5, 4, 5, 4, 4, 3,
8, 8, 8, 7, 8, 7, 7, 6, 8, 7, 7, 6, 7, 6, 6, 3, 8, 7, 7, 6, 7, 6, 6, 4, 7, 6, 6, 4, 6, 4, 4, 3,
8, 7, 7, 6, 7, 6, 6, 5, 7, 6, 6, 5, 6, 5, 5, 3, 7, 6, 6, 5, 6, 5, 5, 4, 6, 5, 5, 4, 5, 4, 4, 3,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 4,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 5, 8, 8, 8, 8, 8, 8, 8, 5, 8, 8, 8, 5, 8, 5, 5, 4,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 6, 8, 8, 8, 8, 8, 8, 8, 6, 8, 8, 8, 6, 8, 6, 6, 4,
8, 8, 8, 8, 8, 8, 8, 6, 8, 8, 8, 6, 8, 6, 6, 5, 8, 8, 8, 6, 8, 6, 6, 5, 8, 6, 6, 5, 6, 5, 5, 4,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 7, 8, 7, 7, 4,
8, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 7, 8, 7, 7, 5, 8, 8, 8, 7, 8, 7, 7, 5, 8, 7, 7, 5, 7, 5, 5, 4,
8, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 7, 8, 7, 7, 6, 8, 8, 8, 7, 8, 7, 7, 6, 8, 7, 7, 6, 7, 6, 6, 4,
8, 8, 8, 7, 8, 7, 7, 6, 8, 7, 7, 6, 7, 6, 6, 5, 8, 7, 7, 6, 7, 6, 6, 5, 7, 6, 6, 5, 6, 5, 5, 4,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 5,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 6,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 6, 8, 8, 8, 8, 8, 8, 8, 6, 8, 8, 8, 6, 8, 6, 6, 5,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 7, 8, 7, 7, 5,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 7, 8, 7, 7, 6,
8, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 7, 8, 7, 7, 6, 8, 8, 8, 7, 8, 7, 7, 6, 8, 7, 7, 6, 7, 6, 6, 5,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 6,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 8, 8, 8, 8, 7, 8, 8, 8, 7, 8, 7, 7, 6,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 7,
];