crates/crc/src/table.rs

use crate::util::*;

pub(crate) const fn crc8_table<const L: usize>(
    width: u8,
    poly: u8,
    reflect: bool,
) -> [[u8; 256]; L] {
    let poly = if reflect {
        let poly = poly.reverse_bits();
        poly >> (8u8 - width)
    } else {
        poly << (8u8 - width)
    };

    let mut table = [[0u8; 256]; L];

    // Generate first table (lane 0) directly
    let mut i = 0;
    while i < 256 && L > 0 {
        table[0][i] = crc8(poly, reflect, i as u8);
        i += 1;
    }

    // Generate subsequent lanes based on lane 0
    if L > 1 {
        let mut i = 0;
        while i < 256 {
            let mut e = 1;
            while e < L {
                let one_lower = table[e - 1][i];
                table[e][i] = table[0][one_lower as usize];
                e += 1;
            }
            i += 1;
        }
    }

    table
}

pub(crate) const fn crc16_table<const L: usize>(
    width: u8,
    poly: u16,
    reflect: bool,
) -> [[u16; 256]; L] {
    let poly = if reflect {
        let poly = poly.reverse_bits();
        poly >> (16u8 - width)
    } else {
        poly << (16u8 - width)
    };

    let mut table = [[0u16; 256]; L];

    // Generate first table (lane 0) directly
    let mut i = 0;
    while i < 256 && L > 0 {
        table[0][i] = crc16(poly, reflect, i as u16);
        i += 1;
    }

    // Generate subsequent lanes based on lane 0
    if L > 1 {
        let mut i = 0;
        while i < 256 {
            let mut e = 1;
            while e < L {
                let one_lower = table[e - 1][i];
                if reflect {
                    table[e][i] = (one_lower >> 8) ^ table[0][(one_lower & 0xFF) as usize];
                } else {
                    table[e][i] = (one_lower << 8) ^ table[0][((one_lower >> 8) & 0xFF) as usize];
                }
                e += 1;
            }
            i += 1;
        }
    }

    table
}

pub(crate) const fn crc32_table<const L: usize>(
    width: u8,
    poly: u32,
    reflect: bool,
) -> [[u32; 256]; L] {
    let poly = if reflect {
        let poly = poly.reverse_bits();
        poly >> (32u8 - width)
    } else {
        poly << (32u8 - width)
    };

    let mut table = [[0u32; 256]; L];

    // Generate first table (lane 0) directly
    let mut i = 0;
    while i < 256 && L > 0 {
        table[0][i] = crc32(poly, reflect, i as u32);
        i += 1;
    }

    // Generate subsequent lanes based on lane 0
    if L > 1 {
        let mut i = 0;
        while i < 256 {
            let mut e = 1;
            while e < L {
                let one_lower = table[e - 1][i];
                if reflect {
                    table[e][i] = (one_lower >> 8) ^ table[0][(one_lower & 0xFF) as usize];
                } else {
                    table[e][i] = (one_lower << 8) ^ table[0][((one_lower >> 24) & 0xFF) as usize];
                }
                e += 1;
            }
            i += 1;
        }
    }

    table
}

pub(crate) const fn crc64_table<const L: usize>(
    width: u8,
    poly: u64,
    reflect: bool,
) -> [[u64; 256]; L] {
    let poly = if reflect {
        let poly = poly.reverse_bits();
        poly >> (64u8 - width)
    } else {
        poly << (64u8 - width)
    };

    let mut table = [[0u64; 256]; L];

    // Generate first table (lane 0) directly
    let mut i = 0;
    while i < 256 && L > 0 {
        table[0][i] = crc64(poly, reflect, i as u64);
        i += 1;
    }

    // Generate subsequent lanes based on lane 0
    if L > 1 {
        let mut i = 0;
        while i < 256 {
            let mut e = 1;
            while e < L {
                let one_lower = table[e - 1][i];
                if reflect {
                    table[e][i] = (one_lower >> 8) ^ table[0][(one_lower & 0xFF) as usize];
                } else {
                    table[e][i] = (one_lower << 8) ^ table[0][((one_lower >> 56) & 0xFF) as usize];
                }
                e += 1;
            }
            i += 1;
        }
    }

    table
}

pub(crate) const fn crc128_table<const L: usize>(
    width: u8,
    poly: u128,
    reflect: bool,
) -> [[u128; 256]; L] {
    let poly = if reflect {
        let poly = poly.reverse_bits();
        poly >> (128u8 - width)
    } else {
        poly << (128u8 - width)
    };

    let mut table = [[0u128; 256]; L];

    // Generate first table (lane 0) directly
    let mut i = 0;
    while i < 256 && L > 0 {
        table[0][i] = crc128(poly, reflect, i as u128);
        i += 1;
    }

    // Generate subsequent lanes based on lane 0
    if L > 1 {
        let mut i = 0;
        while i < 256 {
            let mut e = 1;
            while e < L {
                let one_lower = table[e - 1][i];
                if reflect {
                    table[e][i] = (one_lower >> 8) ^ table[0][(one_lower & 0xFF) as usize];
                } else {
                    table[e][i] = (one_lower << 8) ^ table[0][((one_lower >> 120) & 0xFF) as usize];
                }
                e += 1;
            }
            i += 1;
        }
    }

    table
}