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// secp256k1-zkp bindings
// Written in 2019 by
//   Jonas Nick
//
// To the extent possible under law, the author(s) have dedicated all
// copyright and related and neighboring rights to this software to
// the public domain worldwide. This software is distributed without
// any warranty.
//
// You should have received a copy of the CC0 Public Domain Dedication
// along with this software.
// If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
//

//! # Secp256k1-zkp-sys
//! Low-level (`no_std`) rust bindings for the secp256k1-zkp library.
//! See the `secp256k1-zkp` crate for higher level abstractions.

#![crate_type = "lib"]
#![crate_type = "rlib"]
#![crate_type = "dylib"]
// Coding conventions
#![deny(non_upper_case_globals)]
#![deny(non_camel_case_types)]
#![deny(non_snake_case)]
#![deny(unused_mut)]
#![warn(missing_docs)]
#![cfg_attr(not(test), no_std)]
#![cfg_attr(feature = "dev", allow(unstable_features))]
#![cfg_attr(feature = "dev", feature(plugin))]
#![cfg_attr(feature = "dev", plugin(clippy))]

#[cfg(any(test))]
pub extern crate rand;

#[cfg(feature = "serde")]
pub extern crate serde;
#[cfg(all(feature = "serde", test))]
pub extern crate serde_test;

#[cfg(test)]
extern crate core;
#[cfg(test)]
extern crate secp256k1_zkp_dev;

pub extern crate secp256k1;

#[macro_use]
mod macros;
pub mod ffi;
pub mod schnorrsig;
mod types;

/// The purpose of this rewriteable structure is to replace dynamic memory allocations in the
/// libsecp256k1-zkp library. See its documentation for further information.
pub struct ScratchSpace {
    scratch_space: *mut ffi::ScratchSpace,
}

impl ScratchSpace {
    /// Creates a new scratch space which can hold `max_size` bytges.
    pub fn new<C>(secp256k1: &secp256k1::Secp256k1<C>, max_size: usize) -> ScratchSpace {
        unsafe {
            let space = ffi::secp256k1_zkp_scratch_space_create(*secp256k1.ctx(), max_size);
            ScratchSpace {
                scratch_space: space,
            }
        }
    }
    fn scratch_space(&self) -> *mut ffi::ScratchSpace {
        self.scratch_space
    }
}

impl Drop for ScratchSpace {
    fn drop(&mut self) {
        unsafe {
            ffi::secp256k1_zkp_scratch_space_destroy(self.scratch_space);
        }
    }
}

unsafe impl Send for ScratchSpace {}
unsafe impl Sync for ScratchSpace {}

/// Utility function used to parse hex into a target u8 buffer. Returns
/// the number of bytes converted or an error if it encounters an invalid
/// character or unexpected end of string.
fn from_hex(hex: &str, target: &mut [u8]) -> Result<usize, ()> {
    if hex.len() % 2 == 1 || hex.len() > target.len() * 2 {
        return Err(());
    }

    let mut b = 0;
    let mut idx = 0;
    for c in hex.bytes() {
        b <<= 4;
        match c {
            b'A'...b'F' => b |= c - b'A' + 10,
            b'a'...b'f' => b |= c - b'a' + 10,
            b'0'...b'9' => b |= c - b'0',
            _ => return Err(()),
        }
        if (idx & 1) == 1 {
            target[idx / 2] = b;
            b = 0;
        }
        idx += 1;
    }
    Ok(idx / 2)
}

#[cfg(test)]
mod tests {
    use super::ScratchSpace;
    use secp256k1::Secp256k1;

    #[test]
    fn scratch_space() {
        let s = Secp256k1::new();
        {
            let scratch_space1 = ScratchSpace::new(&s, 0);
            let scratch_space2 = ScratchSpace::new(&s, 100);
            let _ = scratch_space1.scratch_space();
            let _ = scratch_space2.scratch_space();
            // drop
        }
    }
}