sourcepak 0.3.0

//! Helper methods for LZHAM compression and decompression.
//!
//! Uses the [`lzham_alpha_sys`] crate for bindings to the LZHAM alpha library.

use std::mem::size_of;
use std::ptr::null;

use lzham_alpha_sys::{
    lzham_compress_flags_LZHAM_COMP_FLAG_DETERMINISTIC_PARSING,
    lzham_compress_level_LZHAM_COMP_LEVEL_UBER, lzham_compress_memory, lzham_compress_params,
    lzham_decompress_flags_LZHAM_DECOMP_FLAG_COMPUTE_ADLER32,
    lzham_decompress_flags_LZHAM_DECOMP_FLAG_OUTPUT_UNBUFFERED, lzham_decompress_memory,
    lzham_decompress_params, lzham_uint32,
};

const TFLZHAM_DICT_SIZE: u32 = 20; // required for compatibility

const TFLZHAM_COMPRESS_PARAMS: lzham_compress_params = lzham_compress_params {
    m_struct_size: size_of::<lzham_compress_params>() as _,
    m_dict_size_log2: TFLZHAM_DICT_SIZE,
    m_compress_flags: lzham_compress_flags_LZHAM_COMP_FLAG_DETERMINISTIC_PARSING as _,
    m_level: lzham_compress_level_LZHAM_COMP_LEVEL_UBER,
    m_max_helper_threads: -1,
    m_cpucache_total_lines: 0,
    m_cpucache_line_size: 0,
    m_num_seed_bytes: 0,
    m_pSeed_bytes: null(),
};

const TFLZHAM_DECOMPRESS_PARAMS: lzham_decompress_params = lzham_decompress_params {
    m_struct_size: size_of::<lzham_decompress_params>() as _,
    m_dict_size_log2: TFLZHAM_DICT_SIZE,
    m_decompress_flags: (lzham_decompress_flags_LZHAM_DECOMP_FLAG_OUTPUT_UNBUFFERED
        | lzham_decompress_flags_LZHAM_DECOMP_FLAG_COMPUTE_ADLER32) as _,
    m_num_seed_bytes: 0,
    m_pSeed_bytes: null(),
};

pub fn compress(src: &mut Vec<u8>) -> Vec<u8> {
    let mut dst = vec![0; src.len()];
    let mut dst_len = 0;

    let mut adler32: lzham_uint32 = 0;

    let _ = unsafe {
        lzham_compress_memory(
            &TFLZHAM_COMPRESS_PARAMS,
            dst.as_mut_ptr(),
            &mut dst_len,
            src.as_ptr(),
            src.len(),
            &mut adler32,
        );
    };

    dst.truncate(dst_len);

    dst
}

pub fn decompress(src: &Vec<u8>, dst_len: usize) -> Vec<u8> {
    let mut dst = vec![0; dst_len];
    let mut dst_len_new = dst_len;

    let mut adler32: lzham_uint32 = 0;

    let _ = unsafe {
        lzham_decompress_memory(
            &TFLZHAM_DECOMPRESS_PARAMS,
            dst.as_mut_ptr(),
            &mut dst_len_new,
            src.as_ptr(),
            src.len(),
            &mut adler32,
        );
    };

    dst.truncate(dst_len_new);

    dst
}