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#![no_std] #![feature(asm)] use core::ops::*; #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Debug)] pub struct u2size { pub msw: usize, pub lsw: usize, } impl u2size { #[inline] pub fn trailing_zeros(self) -> u32 { self.lsw.trailing_zeros() + (mask32(0 == self.lsw) & self.msw.trailing_zeros()) } #[inline] pub fn count_zeros(self) -> u32 { self.lsw.count_zeros() + self.msw.count_zeros() } #[inline] pub fn count_ones(self) -> u32 { self.lsw.count_ones() + self.msw.count_ones() } #[inline] pub fn rotate_left(self, k: u32) -> Self { u2size { msw: shld(self.msw, self.lsw, k), lsw: shld(self.lsw, self.msw, k), } } #[inline] pub fn rotate_right(self, k: u32) -> Self { u2size { msw: shrd(self.msw, self.lsw, k), lsw: shrd(self.lsw, self.msw, k), } } #[inline] pub fn overflowing_add(x: Self, y: Self) -> (Self, bool) { let (lsw, c) = addc(x.lsw, y.lsw, false); let (msw, c) = addc(x.msw, y.msw, c); (u2size { msw, lsw }, c) } #[inline] pub fn overflowing_sub(x: Self, y: Self) -> (Self, bool) { let (lsw, c) = subc(x.lsw, y.lsw, false); let (msw, c) = subc(x.msw, y.msw, c); (u2size { msw, lsw }, c) } #[inline] pub fn overflowing_mul(u2size { msw: x1, lsw: x0 }: Self, u2size { msw: y1, lsw: y0 }: Self) -> (Self, bool) { let c2 = 0 != x1 && 0 != y1; let (c0, z0) = carrying_mul(x0, y0); let (z1x, c1x) = usize::overflowing_mul(x0, y1); let (z1y, c1y) = usize::overflowing_mul(y0, x1); let (z1z, c1z) = usize::overflowing_add(z1x, z1y); let (z1, c) = addc(z1z, c0, c1z); (u2size { msw: z1, lsw: z0 }, c1x | c1y | c2 | c) } } impl From<usize> for u2size { #[inline] fn from(n: usize) -> Self { u2size { msw: 0, lsw: n } } } impl Shr<u32> for u2size { type Output = Self; #[inline] fn shr(self, k: u32) -> Self { if k < word_bits { u2size { msw: self.msw >> k, lsw: shrd(self.lsw, self.msw, k), } } else { Self::from(self.msw >> (k - word_bits)) } } } impl Shl<u32> for u2size { type Output = Self; #[inline] fn shl(self, k: u32) -> Self { if k < word_bits { u2size { msw: shld(self.msw, self.lsw, k), lsw: self.lsw << k, } } else { u2size { msw: self.lsw << (k - word_bits), lsw: 0, } } } } impl BitXor for u2size { type Output = Self; #[inline] fn bitxor(self, other: Self) -> Self { u2size { msw: self.msw ^ other.msw, lsw: self.lsw ^ other.lsw } } } impl BitXorAssign for u2size { #[inline] fn bitxor_assign(&mut self, other: Self) { *self = *self ^ other } } impl BitAnd for u2size { type Output = Self; #[inline] fn bitand(self, other: Self) -> Self { u2size { msw: self.msw & other.msw, lsw: self.lsw & other.lsw } } } impl BitAndAssign for u2size { #[inline] fn bitand_assign(&mut self, other: Self) { *self = *self & other } } impl BitOr for u2size { type Output = Self; #[inline] fn bitor(self, other: Self) -> Self { u2size { msw: self.msw | other.msw, lsw: self.lsw | other.lsw } } } impl BitOrAssign for u2size { #[inline] fn bitor_assign(&mut self, other: Self) { *self = *self | other } } impl Add for u2size { type Output = Self; #[inline] fn add(self, other: Self) -> Self { Self::overflowing_add(self, other).0 } } impl AddAssign for u2size { #[inline] fn add_assign(&mut self, other: Self) { *self = *self + other } } impl Sub for u2size { type Output = Self; #[inline] fn sub(self, other: Self) -> Self { Self::overflowing_sub(self, other).0 } } impl SubAssign for u2size { #[inline] fn sub_assign(&mut self, other: Self) { *self = *self - other } } impl Mul for u2size { type Output = Self; #[inline] fn mul(self, other: Self) -> Self { Self::overflowing_mul(self, other).0 } } impl MulAssign for u2size { #[inline] fn mul_assign(&mut self, other: Self) { *self = *self * other } } #[inline(always)] fn shld(x: usize, y: usize, k: u32) -> usize { x << k | mask(0 == k) & y >> (k.wrapping_neg() & (word_bits - 1)) } #[inline(always)] fn shrd(x: usize, y: usize, k: u32) -> usize { x >> k | mask(0 == k) & y << (k.wrapping_neg() & (word_bits - 1)) } #[inline(always)] fn addc(x: usize, y: usize, c: bool) -> (usize, bool) { let (z, c1) = usize::overflowing_add(x, y); let (z, c2) = usize::overflowing_add(z, c as usize); (z, c1 || c2) } #[inline(always)] fn subc(x: usize, y: usize, c: bool) -> (usize, bool) { let (z, c1) = usize::overflowing_sub(x, y); let (z, c2) = usize::overflowing_sub(z, c as usize); (z, c1 || c2) } #[inline(always)] fn mask(b: bool) -> usize { (b as usize).wrapping_neg() } #[inline(always)] fn mask32(b: bool) -> u32 { (b as u32).wrapping_neg() } const word_bits: u32 = (::core::mem::size_of::<usize>() << 3) as u32; #[cfg(target_arch = "x86_64")] #[inline(always)] fn carrying_mul(x: usize, y: usize) -> (usize, usize) { let mut c: usize; let mut z: usize; unsafe { asm!("mulq $3" : "={rax}"(z), "={rdx}"(c) : "{rax}"(x), "r"(y)) } (c, z) } #[cfg(not(target_arch = "x86_64"))] #[inline(always)] fn carrying_mul(x: usize, y: usize) -> (usize, usize) { let n = 0usize.count_zeros() >> 1; let halves = |x| (x >> n, x & !0 >> n); let ((x1, x0), (y1, y0)) = (halves(x), halves(y)); let (z2, z0) = (x1 * y1, x0 * y0); let z1 = (x1 + x0) * (y1 + y0) - z2 - z0; let (w, c) = usize::overflowing_add(z0, z1 << n); (z2 + (z1 >> n) + c as usize, w) }