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pub(crate) fn rng_32() -> u32 {
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
{
if is_x86_feature_detected!("rdrand") {
let mut x: u32 = 0;
unsafe { core::arch::x86_64::_rdrand32_step(&mut x) };
return x;
}
}
{
let mut seed = std::time::Instant::now().elapsed().as_nanos() as u64; for _ in 0..10 {
seed = seed
.overflowing_mul(18029154779448018981u64)
.0
.overflowing_add(3935559000370003845u64)
.0
}
(seed >> 32) as u32
}
}
pub(crate) fn rng_64() -> u64 {
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
{
if is_x86_feature_detected!("rdrand") {
let mut x: u64 = 0;
unsafe { core::arch::x86_64::_rdrand64_step(&mut x) };
return x;
}
}
{
let mut seed = std::time::Instant::now().elapsed().as_nanos() as u64;
for _ in 0..10 {
seed = seed
.overflowing_mul(18029154779448018981u64)
.0
.overflowing_add(3935559000370003845u64)
.0
}
seed
}
}
#[inline(always)]
pub(crate) const fn split(x: u128) -> (u64, u64) {
unsafe { std::mem::transmute::<u128, (u64, u64)>(x) }
}
#[inline(always)]
pub(crate) const fn fuse(hi: u64, lo: u64) -> u128 {
unsafe { std::mem::transmute::<(u64, u64), u128>((lo, hi)) }
}
#[inline]
pub(crate) fn adc(carry: u8, x: u64, y: u64, output: &mut u64) -> u8 {
unsafe { core::arch::x86_64::_addcarry_u64(carry, x, y, output) }
}
#[inline]
pub(crate) fn sbb(carry: u8, x: u64, y: u64, output: &mut u64) -> u8 {
unsafe { core::arch::x86_64::_subborrow_u64(carry, x, y, output) }
}
#[inline]
pub(crate) fn carry_mul(carry: u64, x: u64, y: u64, output: &mut u64) -> u64 {
let product = (x as u128 * y as u128) + carry as u128;
let (jtmp, car) = split(product);
*output = jtmp;
car
}
#[inline]
pub(crate) fn mul_acc(carry: u64, x: u64, y: u64, acc: &mut u128) -> u64 {
*acc += carry as u128;
*acc += x as u128 * y as u128;
let lo = *acc as u64;
*acc >>= 64;
lo
}
#[inline]
pub(crate) fn carry_div(carry: u64, x: u64, y: u64, output: &mut u64) -> u64 {
let num = fuse(carry, x);
let factor = num / y as u128;
*output = factor as u64;
(num % y as u128) as u64
}
#[inline]
pub(crate) fn carry_mod(carry: u64, x: u64, y: u64) -> u64 {
let num = fuse(carry, x);
(num % y as u128) as u64
}
#[inline]
pub(crate) fn wide_div(upper: u64, lower: u64, divisor: u64) -> (u64, u64) {
let interim = fuse(upper, lower);
(
(interim / divisor as u128) as u64,
(interim % divisor as u128) as u64,
)
}
pub(crate) fn divide3by2(ahi: u64, amid: u64, alo: u64, bhi: u64, blo: u64) -> u64 {
let (mut q0, mut r) = if ahi < bhi {
let (q0, r) = wide_div(ahi, amid, bhi);
(q0, r as u128)
} else {
(u64::MAX, ahi as u128 + amid as u128)
};
while r <= u64::MAX as u128
&& unsafe { std::mem::transmute::<(u64, u64), u128>((alo, r as u64)) }
< q0 as u128 * blo as u128
{
q0 -= 1;
r += blo as u128;
}
q0
}
#[inline]
pub(crate) fn carry_shl(carry: u64, x: u64, places: u32, output: &mut u64) -> u64 {
*output = (x.overflowing_shl(places).0) | carry;
unsafe { core::arch::x86_64::_bextr_u64(x, 64 - places, 64) }
}
#[inline]
pub(crate) fn carry_shr(carry: u64, x: u64, places: u32, output: &mut u64) -> u64 {
*output = (x >> places) | carry;
if places == 0 {
return 0;
}
unsafe { core::arch::x86_64::_bextr_u64(x, 0, places) << (64 - places) }
}
pub(crate) fn remove_lead_zeros(x: &mut Vec<u64>) {
if let Some(&0) = x.last() {
let len = x.iter().rposition(|&d| d != 0).map_or(0, |i| i + 1);
x.truncate(len);
}
if x.len() < x.capacity() / 4 {
x.shrink_to_fit();
}
}