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#![cfg(feature = "gzip")]
use crate::crc::crc_tables::{CRC32_SLICE1_TABLE, CRC32_SLICE8_TABLE};
mod crc_tables;
/// Calculate crc for a data and an initial crc value
#[allow(clippy::identity_op, clippy::zero_prefixed_literal)]
pub fn crc32(data: &[u8], mut crc: u32) -> u32
{
// main loop
for chunk in data.chunks_exact(8)
{
let chunk_loaded = u64::from_le_bytes(chunk.try_into().unwrap());
let v1 = (chunk_loaded & u64::from(u32::MAX)) as u32;
let v2 = (chunk_loaded >> 32) as u32;
crc = CRC32_SLICE8_TABLE[0x700 + (((crc ^ v1) >> 00) & 0xFF) as usize]
^ CRC32_SLICE8_TABLE[0x600 + (((crc ^ v1) >> 08) & 0xFF) as usize]
^ CRC32_SLICE8_TABLE[0x500 + (((crc ^ v1) >> 16) & 0xFF) as usize]
^ CRC32_SLICE8_TABLE[0x400 + (((crc ^ v1) >> 24) & 0xFF) as usize]
^ CRC32_SLICE8_TABLE[0x300 + (((v2 >> 00) & 0xFF) as usize)]
^ CRC32_SLICE8_TABLE[0x200 + (((v2 >> 08) & 0xFF) as usize)]
^ CRC32_SLICE8_TABLE[0x100 + (((v2 >> 16) & 0xFF) as usize)]
^ CRC32_SLICE8_TABLE[0x000 + (((v2 >> 24) & 0xFF) as usize)];
}
// handle remainder
for remainder in data.chunks_exact(8).remainder()
{
crc = (crc >> 8) ^ CRC32_SLICE1_TABLE[((crc & 0xFF) ^ u32::from(*remainder)) as usize];
}
crc
}
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