sssmc39 0.0.3

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//
// Modifications Copyright 2019 The Grin Developers
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
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//     http://www.apache.org/licenses/LICENSE-2.0
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use crate::field::gf256::Gf256;
use std::fmt;

static MAX_COEFFS: usize = 256;

pub struct Poly {
	pub coeffs: Vec<Gf256>,
}

impl fmt::Debug for Poly {
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
		let _ = write!(f, "(");
		for i in 0..self.coeffs.len() {
			let _ = write!(f, "{:?}, ", self.coeffs[i]);
		}
		writeln!(f, ")")
	}
}

impl Poly {
	pub fn new(coeffs: Vec<Gf256>) -> Self {
		Self { coeffs }
	}

	pub fn _evaluate_at_zero(&self) -> Gf256 {
		self.coeffs[0]
	}

	pub fn evaluate_at(&self, x: Gf256) -> Gf256 {
		assert!(self.coeffs.len() < MAX_COEFFS);

		let mut result = Gf256::zero();

		for (i, c) in self.coeffs.iter().enumerate() {
			result += *c * x.pow(i as u8);
		}

		result
	}
}