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/*
==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--

Zeros

Copyright (C) 2019-2023  Anonymous

There are several releases over multiple years,
they are listed as ranges, such as: "2019-2023".

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

This program 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 Lesser General Public License for more details.

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

::--::--::--::--::--::--::--::--::--::--::--::--::--::--::--::--
*/

//! # Indexing Block

use {
    crate::Result,
    super::{
        Argon2,
        block::{Block, WORD_ARRAY_LEN, Word, ZEROS},
        job,
    },
};

/// # Indexing Block
#[derive(Debug, Clone)]
pub (super) struct IndexingBlock {
    block: Block,
}

impl IndexingBlock {

    /// # Makes new instance
    pub fn new(mem_blocks: u32, passes: u32, argon2: &Argon2) -> Self {
        let mut block = ZEROS;
        {
            let block = block.as_mut_words();
            block[3] = Word::from(mem_blocks);
            block[4] = Word::from(passes);
            block[5] = Word::from(argon2.id());
        }
        Self {
            block,
        }
    }

    /// # Updates and calculates next J1, J2
    pub fn next(&mut self, pass: u32, row: usize, slice: usize, sub_segment_index: usize) -> Result<(Word, Word)> {
        let b = self.block.as_mut_words();
        (|| Some({
            b[0] = Word::from(pass);
            b[1] = Word::try_from(row).ok()?;
            b[2] = Word::try_from(slice).ok()?;
            b[6] = Word::try_from((sub_segment_index / WORD_ARRAY_LEN).checked_add(1)?).ok()?;
        }))().ok_or_else(|| err!())?;

        let b = job::compress(&ZEROS, &job::compress(&ZEROS, &self.block)).as_words()[sub_segment_index % WORD_ARRAY_LEN];
        Ok((b & 0x_0000_0000_ffff_ffff, b >> 32))
    }

}