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// Copyright 2021 Centrifuge Foundation (centrifuge.io).
//
// This file is part of the Centrifuge chain project.
// Centrifuge 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 (see http://www.gnu.org/licenses).
// Centrifuge 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.
// Ensure we're `no_std` when compiling for WebAssembly.
#![cfg_attr(not(feature = "std"), no_std)]
use parity_scale_codec::Encode;
use sp_std::cmp::min;
pub struct BufferReader<'a>(pub &'a [u8]);
impl<'a> BufferReader<'a> {
pub fn read_bytes(&mut self, bytes: usize) -> Option<&[u8]> {
if self.0.len() < bytes {
return None;
}
let (consumed, remaining) = self.0.split_at(bytes);
self.0 = remaining;
Some(consumed)
}
pub fn read_array<const N: usize>(&mut self) -> Option<&[u8; N]> {
let (consumed, remaining) = self.0.split_first_chunk::<N>()?;
self.0 = remaining;
Some(consumed)
}
}
/// Build a fixed-size array using as many elements from `src` as possible
/// without overflowing and ensuring that the array is 0 padded in the case
/// where `src.len()` is smaller than S.
pub fn vec_to_fixed_array<const S: usize>(src: impl AsRef<[u8]>) -> [u8; S] {
let mut dest = [0; S];
let len = min(src.as_ref().len(), S);
dest[..len].copy_from_slice(&src.as_ref()[..len]);
dest
}
/// Function that initializes the frame system & Aura, so a timestamp can be set
/// and pass validation
#[cfg(any(feature = "runtime-benchmarks", feature = "std"))]
pub fn set_block_number_timestamp<T>(
block_number: frame_system::pallet_prelude::BlockNumberFor<T>,
timestamp: T::Moment,
) where
T: pallet_aura::Config + frame_system::Config + pallet_timestamp::Config,
{
use frame_support::traits::Hooks;
use sp_consensus_aura::AURA_ENGINE_ID;
use sp_runtime::{Digest, DigestItem};
use sp_std::vec;
let slot = timestamp / pallet_aura::Pallet::<T>::slot_duration();
let digest = Digest {
logs: vec![DigestItem::PreRuntime(AURA_ENGINE_ID, slot.encode())],
};
frame_system::Pallet::<T>::initialize(&block_number, &Default::default(), &digest);
pallet_aura::Pallet::<T>::on_initialize(block_number);
pallet_timestamp::Pallet::<T>::set_timestamp(timestamp);
}
pub mod math {
use sp_arithmetic::{
traits::{BaseArithmetic, EnsureFixedPointNumber},
ArithmeticError, FixedPointOperand, FixedU128,
};
/// Returns the coordinate `y` for coordinate `x`,
/// in a function given by 2 points: (x1, y1) and (x2, y2)
pub fn y_coord_in_rect<X, Y>(
(x1, y1): (X, Y),
(x2, y2): (X, Y),
x: X,
) -> Result<Y, ArithmeticError>
where
X: BaseArithmetic + FixedPointOperand,
Y: BaseArithmetic + FixedPointOperand,
{
// From the equation: (x - x1) / (x2 - x1) == (y - y1) / (y2 - y1) we solve y:
//
// NOTE: With rects that have x or y negative directions, we emulate a
// symmetry in those axis to avoid unsigned underflows in substractions. It
// means, we first "convert" the rect into an increasing rect, and in such rect,
// we find the y coordinate.
let left = if x1 <= x2 {
FixedU128::ensure_from_rational(x.ensure_sub(x1)?, x2.ensure_sub(x1)?)?
} else {
// X symmetry emulation
FixedU128::ensure_from_rational(x1.ensure_sub(x)?, x1.ensure_sub(x2)?)?
};
if y1 <= y2 {
left.ensure_mul_int(y2.ensure_sub(y1)?)?.ensure_add(y1)
} else {
// Y symmetry emulation
y1.ensure_sub(left.ensure_mul_int(y1.ensure_sub(y2)?)?)
}
}
/// Converts the given number to percent.
///
/// # Example
///
/// ```
/// use sp_arithmetic::FixedI64;
/// use cfg_utils::math::to_percent;
///
/// assert_eq!(to_percent(3u128), FixedI64::from_rational(3, 100));
/// ```
pub const fn to_percent(x: u128) -> sp_arithmetic::FixedI64 {
sp_arithmetic::FixedI64::from_rational(x, 100)
}
/// Converts the given number to parts per million
///
/// # Example
///
/// ```
/// use sp_arithmetic::FixedI64;
/// use cfg_utils::math::to_ppm;
///
/// assert_eq!(to_ppm(3u128), FixedI64::from_rational(3, 1_000_000));
/// ```
pub const fn to_ppm(x: u128) -> sp_arithmetic::FixedI64 {
sp_arithmetic::FixedI64::from_rational(x, 1_000_000)
}
#[cfg(test)]
mod test_y_coord_in_function_with_2_points {
use super::*;
#[test]
fn start_point() {
assert_eq!(y_coord_in_rect::<u32, u32>((3, 12), (7, 24), 3), Ok(12));
}
#[test]
fn end_point() {
assert_eq!(y_coord_in_rect::<u32, u32>((3, 12), (7, 24), 7), Ok(24));
}
// Rect defined as:
// (x2, y2)
// /
// /
// (x1, y1)
#[test]
fn inner_point() {
assert_eq!(y_coord_in_rect::<u32, u32>((3, 12), (7, 24), 4), Ok(15));
}
// Rect defined as:
// (x2, y2)
// \
// \
// (x1, y1)
#[test]
fn inner_point_with_greater_x1() {
assert_eq!(y_coord_in_rect::<u32, u32>((7, 12), (3, 24), 4), Ok(21));
}
// Rect defined as:
// (x1, y1)
// \
// \
// (x2, y2)
#[test]
fn inner_point_with_greater_y1() {
assert_eq!(y_coord_in_rect::<u32, u32>((3, 24), (7, 12), 4), Ok(21));
}
// Rect defined as:
// (x1, y1)
// /
// /
// (x2, y2)
#[test]
fn inner_point_with_greater_x1y1() {
assert_eq!(y_coord_in_rect::<u32, u32>((7, 24), (3, 12), 4), Ok(15));
}
}
}
#[cfg(test)]
mod tests {
use super::*;
mod vec_to_fixed_array {
use super::*;
// Verify that `vec_to_fixed_array` converts a source Vec that's shorter than
// the desired output fixed-array by copying all elements of source and filling
// the remaining bytes to 0.
#[test]
fn short_source() {
let src = "TrNcH".as_bytes().to_vec();
let symbol: [u8; 32] = vec_to_fixed_array(src.clone());
assert!(symbol.starts_with("TrNcH".as_bytes()));
assert_eq!(
symbol,
[
84, 114, 78, 99, 72, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0
]
);
}
// Verify that `vec_to_fixed_array` converts a source Vec that's exactly as big
// the desired output fixed-array by copying all elements of source to said
// array.
#[test]
fn max_source() {
let src: Vec<u8> = (0..32).collect();
let symbol: [u8; 32] = vec_to_fixed_array(src.clone());
assert_eq!(
symbol,
[
0, 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
]
);
}
// Verify that `vec_to_fixed_array` converts a source Vec that's longer than the
// desired output fixed-array by copying all elements of source until said array
// is full.
#[test]
fn exceeding_source() {
let src: Vec<u8> = (0..64).collect();
let symbol: [u8; 32] = vec_to_fixed_array(src.clone());
assert_eq!(
symbol,
[
0, 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
]
);
}
}
}