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#[derive(Copy)] pub struct Hc256Rng { p: [u32; 1024], q: [u32; 1024], c: usize } impl Clone for Hc256Rng { fn clone(&self) -> Hc256Rng { *self } } impl Hc256Rng { pub fn init(key: &[u32; 8], iv: &[u32; 8]) -> Hc256Rng { let mut w = [0; 2560]; w[..8].copy_from_slice(key); w[8..16].copy_from_slice(iv); Self::with_w(&mut w) } pub fn with_w(w: &mut [u32; 2560]) -> Hc256Rng { let mut hc256 = Hc256Rng { p: [0; 1024], q: [0; 1024], c: 0 }; for i in 16..2560 { w[i] = f2(w[i - 2]) .wrapping_add(w[i - 7]) .wrapping_add(f1(w[i - 15])) .wrapping_add(w[i - 16]) .wrapping_add(i as u32); } hc256.p.copy_from_slice(&w[512..1536]); hc256.q.copy_from_slice(&w[1536..]); for _ in 0..4096 { hc256.gen(); } hc256 } pub fn gen(&mut self) -> u32 { let i = self.c & 0x3ff; let i3 = i.wrapping_sub(3) & 0x3ff; let i10 = i.wrapping_sub(10) & 0x3ff; let i12 = i.wrapping_sub(12) & 0x3ff; let i1023 = i.wrapping_sub(1023) & 0x3ff; let output = if self.c < 1024 { self.p[i] = self.p[i] .wrapping_add(self.p[i10]) .wrapping_add(self.p[i3].rotate_right(10) ^ self.p[i1023].rotate_right(23)) .wrapping_add(self.q[(self.p[i3] ^ self.p[i1023]) as usize & 0x3ff]); h(&self.q, self.p[i12]) ^ self.p[i] } else { self.q[i] = self.q[i] .wrapping_add(self.q[i10]) .wrapping_add(self.q[i3].rotate_right(10) ^ self.q[i1023].rotate_right(23)) .wrapping_add(self.p[(self.q[i3] ^ self.q[i1023]) as usize & 0x3ff]); h(&self.p, self.q[i12]) ^ self.q[i] }; self.c = (self.c + 1) & 0x7ff; output } } #[inline] fn h(q: &[u32], u: u32) -> u32 { q[(u & 0xff) as usize] .wrapping_add(q[256 + (u >> 8 & 0xff) as usize]) .wrapping_add(q[512 + (u >> 16 & 0xff) as usize]) .wrapping_add(q[768 + (u >> 24 & 0xff) as usize]) } #[inline] fn f1(x: u32) -> u32 { x.rotate_right(7) ^ x.rotate_right(18) ^ x.wrapping_shr(3) } #[inline] fn f2(x: u32) -> u32 { x.rotate_right(17) ^ x.rotate_right(19) ^ x.wrapping_shr(10) } #[test] fn test() { assert_eq!( Hc256Rng::init(&[0; 8], &[0; 8]).gen(), 2240350043 ); }