ziskos 1.3.0-alpha

Guest runtime and entrypoint for programs targeting the ZisK zkVM
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//! syscall_babyjubjub_add system call interception

#[cfg(zisk_guest)]
use crate::ziskos_syscall;

#[cfg(zisk_guest)]
use core::arch::asm;

use super::point::SyscallPoint256;

#[derive(Debug)]
#[repr(C)]
pub struct SyscallBabyJubJubAddParams<'a> {
    pub p1: &'a mut SyscallPoint256,
    pub p2: &'a SyscallPoint256,
}

/// Performs the addition of two points on the BabyJubJub (twisted Edwards) curve, storing the
/// result in the first point.
///
/// `BabyJubJubAdd` operates on two affine points `(x, y)`, each coordinate being a 256-bit element
/// of the BN254 scalar field. Each coordinate is represented as an array of four `u64` elements.
/// The syscall takes as a parameter the address of a structure containing points `p1` and `p2`.
/// The result of the addition is stored in `p1`.
///
/// The BabyJubJub addition law is complete, so the same formula doubles a point; to double `P`,
/// pass `p1 = p2 = P`.
///
/// ### Safety
///
/// The caller must ensure that the data is aligned to a 64-bit boundary.
///
/// The caller must ensure that the points `p1` and `p2` are valid points on the BabyJubJub curve.
///
/// The caller must ensure that both `p1` and `p2` coordinates are within the range of the BN254
/// scalar field.
///
/// The resulting point will have both coordinates in the range of the BN254 scalar field.
#[allow(unused_variables)]
#[cfg_attr(not(feature = "hints"), no_mangle)]
#[cfg_attr(feature = "hints", export_name = "hints_syscall_babyjubjub_add")]
pub extern "C" fn syscall_babyjubjub_add(
    params: &mut SyscallBabyJubJubAddParams,
    #[cfg(feature = "hints")] hints: &mut Vec<u64>,
) {
    #[cfg(zisk_guest)]
    ziskos_syscall!(zisk_definitions::SYSCALL_BABYJUBJUB_ADD_ID, params);
    #[cfg(not(zisk_guest))]
    {
        let p1 = [params.p1.x, params.p1.y].concat().try_into().unwrap();
        let p2 = [params.p2.x, params.p2.y].concat().try_into().unwrap();
        let mut p3: [u64; 8] = [0; 8];
        zisk_precomp_helpers::babyjubjub_add(&p1, &p2, &mut p3);
        params.p1.x.copy_from_slice(&p3[0..4]);
        params.p1.y.copy_from_slice(&p3[4..8]);
        #[cfg(feature = "hints")]
        {
            hints.extend_from_slice(&p3);
        }
    }
}