1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154

// Copyright 2015-2020 Parity Technologies (UK) Ltd.
// This file is part of OpenEthereum.

// OpenEthereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// OpenEthereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.

use primal::is_prime;

pub const DATASET_BYTES_INIT: u64 = 1 << 30;
pub const DATASET_BYTES_GROWTH: u64 = 1 << 23;
pub const CACHE_BYTES_INIT: u64 = 1 << 24;
pub const CACHE_BYTES_GROWTH: u64 = 1 << 17;

pub const ETHASH_EPOCH_LENGTH: u64 = 30000;
pub const ETHASH_CACHE_ROUNDS: usize = 3;
pub const ETHASH_MIX_BYTES: usize = 128;
pub const ETHASH_ACCESSES: usize = 64;
pub const ETHASH_DATASET_PARENTS: u32 = 256;
pub const NODE_DWORDS: usize = NODE_WORDS / 2;
pub const NODE_WORDS: usize = NODE_BYTES / 4;
pub const NODE_BYTES: usize = 64;

pub fn epoch(block_number: u64) -> u64 {
    block_number / ETHASH_EPOCH_LENGTH
}

static CHARS: &'static [u8] = b"0123456789abcdef";
pub fn to_hex(bytes: &[u8]) -> String {
    let mut v = Vec::with_capacity(bytes.len() * 2);
    for &byte in bytes.iter() {
        v.push(CHARS[(byte >> 4) as usize]);
        v.push(CHARS[(byte & 0xf) as usize]);
    }

    unsafe { String::from_utf8_unchecked(v) }
}

pub fn get_cache_size(block_number: u64) -> usize {
    // TODO: Memoise
    let mut sz: u64 = CACHE_BYTES_INIT + CACHE_BYTES_GROWTH * (block_number / ETHASH_EPOCH_LENGTH);
    sz = sz - NODE_BYTES as u64;
    while !is_prime(sz / NODE_BYTES as u64) {
        sz = sz - 2 * NODE_BYTES as u64;
    }
    sz as usize
}

pub fn get_data_size(block_number: u64) -> usize {
    // TODO: Memoise
    let mut sz: u64 =
        DATASET_BYTES_INIT + DATASET_BYTES_GROWTH * (block_number / ETHASH_EPOCH_LENGTH);
    sz = sz - ETHASH_MIX_BYTES as u64;
    while !is_prime(sz / ETHASH_MIX_BYTES as u64) {
        sz = sz - 2 * ETHASH_MIX_BYTES as u64;
    }
    sz as usize
}

pub type NodeBytes = [u8; NODE_BYTES];
pub type NodeWords = [u32; NODE_WORDS];
pub type NodeDwords = [u64; NODE_DWORDS];

macro_rules! static_assert_size_eq {
	(@inner $a:ty, $b:ty, $($rest:ty),*) => {
		fn first() {
			static_assert_size_eq!($a, $b);
		}

		fn second() {
			static_assert_size_eq!($b, $($rest),*);
		}
	};
	(@inner $a:ty, $b:ty) => {
		unsafe {
			let val: $b = ::mem::MaybeUninit::uninit().assume_init();
			let _: $a = ::std::mem::transmute(val);
		}
	};
	($($rest:ty),*) => {
		static_assert_size_eq!(size_eq: $($rest),*);
	};
	($name:ident : $($rest:ty),*) => {
		#[allow(dead_code)]
		fn $name() {
			static_assert_size_eq!(@inner $($rest),*);
		}
	};
}

static_assert_size_eq!(Node, NodeBytes, NodeWords, NodeDwords);

#[repr(C)]
pub union Node {
    pub dwords: NodeDwords,
    pub words: NodeWords,
    pub bytes: NodeBytes,
}

impl Clone for Node {
    fn clone(&self) -> Self {
        unsafe {
            Node {
                bytes: *&self.bytes,
            }
        }
    }
}

// We use `inline(always)` because I was experiencing an 100% slowdown and `perf` showed that these
// calls were taking up ~30% of the runtime. Adding these annotations fixes the issue. Remove at
// your peril, if and only if you have benchmarks to prove that this doesn't reintroduce the
// performance regression. It's not caused by the `debug_assert_eq!` either, your guess is as good
// as mine.
impl Node {
    #[inline(always)]
    pub fn as_bytes(&self) -> &NodeBytes {
        unsafe { &self.bytes }
    }

    #[inline(always)]
    pub fn as_bytes_mut(&mut self) -> &mut NodeBytes {
        unsafe { &mut self.bytes }
    }

    #[inline(always)]
    pub fn as_words(&self) -> &NodeWords {
        unsafe { &self.words }
    }

    #[inline(always)]
    pub fn as_words_mut(&mut self) -> &mut NodeWords {
        unsafe { &mut self.words }
    }

    #[inline(always)]
    pub fn as_dwords(&self) -> &NodeDwords {
        unsafe { &self.dwords }
    }

    #[inline(always)]
    pub fn as_dwords_mut(&mut self) -> &mut NodeDwords {
        unsafe { &mut self.dwords }
    }
}