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Use macros to avoid code duplication in CRC tables generation. #94

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Use macros to avoid code duplication in CRC tables generation. #94

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301 changes: 69 additions & 232 deletions src/table.rs
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Original file line number Diff line number Diff line change
@@ -1,247 +1,84 @@
use crate::util::*;

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

let mut table = [0u8; 256];
let mut i = 0;
while i < table.len() {
table[i] = crc8(poly, reflect, i as u8);
i += 1;
}
table
}

pub(crate) const fn crc8_table_slice_16(width: u8, poly: u8, reflect: bool) -> [[u8; 256]; 16] {
let poly = if reflect {
let poly = poly.reverse_bits();
poly >> (8u8 - width)
} else {
poly << (8u8 - width)
};

let mut table = [[0u8; 256]; 16];
let mut i = 0;
while i < 256 {
table[0][i] = crc8(poly, reflect, i as u8);
i += 1;
}

let mut i = 0;
while i < 256 {
let mut e = 1;
while e < 16 {
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(width: u8, poly: u16, reflect: bool) -> [u16; 256] {
let poly = if reflect {
let poly = poly.reverse_bits();
poly >> (16u8 - width)
} else {
poly << (16u8 - width)
};

let mut table = [0u16; 256];
let mut i = 0;
while i < table.len() {
table[i] = crc16(poly, reflect, i as u16);
i += 1;
}
table
}

pub(crate) const fn crc16_table_slice_16(width: u8, poly: u16, reflect: bool) -> [[u16; 256]; 16] {
let poly = if reflect {
let poly = poly.reverse_bits();
poly >> (16u8 - width)
} else {
poly << (16u8 - width)
};

let mut table = [[0u16; 256]; 16];
let mut i = 0;
while i < 256 {
table[0][i] = crc16(poly, reflect, i as u16);
i += 1;
}

let mut i = 0;
while i < 256 {
let mut e = 1;
while e < 16 {
let one_lower = table[e - 1][i];
if reflect {
table[e][i] = (one_lower >> 8) ^ table[0][(one_lower & 0xFF) as usize];
macro_rules! impl_crc_table {
($name: ident, $ty: ty, $base: path) => {
pub(crate) const fn $name(width: u8, poly: $ty, reflect: bool) -> [$ty; 256] {
const BITS: usize = ::core::mem::size_of::<$ty>() * 8;

let poly = if reflect {
let poly = poly.reverse_bits();
poly >> (BITS - width as usize)
} else {
table[e][i] = (one_lower << 8) ^ table[0][((one_lower >> 8) & 0xFF) as usize];
poly << (BITS - width as usize)
};

let mut table = [0 as $ty; 256];
let mut i = 0;
while i < table.len() {
table[i] = $base(poly, reflect, i as $ty);
i += 1;
}
e += 1;
table
}
i += 1;
}
table
}

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

let mut table = [0u32; 256];
let mut i = 0;
while i < 256 {
table[i] = crc32(poly, reflect, i as u32);
i += 1;
}

table
}

pub(crate) const fn crc32_table_slice_16(width: u8, poly: u32, reflect: bool) -> [[u32; 256]; 16] {
let poly = if reflect {
let poly = poly.reverse_bits();
poly >> (32u8 - width)
} else {
poly << (32u8 - width)
};

let mut table = [[0u32; 256]; 16];
let mut i = 0;
while i < 256 {
table[0][i] = crc32(poly, reflect, i as u32);
i += 1;
}

let mut i = 0;
while i < 256 {
let mut e = 1;
while e < 16 {
let one_lower = table[e - 1][i];
if reflect {
table[e][i] = (one_lower >> 8) ^ table[0][(one_lower & 0xFF) as usize];
macro_rules! impl_crc_slice_table {
($name: ident, $ty: ty, $slices: expr, $base: path) => {
pub(crate) const fn $name(width: u8, poly: $ty, reflect: bool) -> [[$ty; 256]; $slices] {
const BITS: usize = ::core::mem::size_of::<$ty>() * 8;
// to avoid compiler arithmetic_overflow error
const SHIFT: usize = if BITS > 8 { 8 } else { 0 };

let poly = if reflect {
let poly = poly.reverse_bits();
poly >> (BITS - width as usize)
} else {
table[e][i] = (one_lower << 8) ^ table[0][((one_lower >> 24) & 0xFF) as usize];
poly << (BITS - width as usize)
};

let mut table = [[0 as $ty; 256]; $slices];
let mut i = 0;
while i < 256 {
table[0][i] = $base(poly, reflect, i as $ty);
i += 1;
}
e += 1;
}
i += 1;
}
table
}

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

let mut table = [0u64; 256];
let mut i = 0;
while i < table.len() {
table[i] = crc64(poly, reflect, i as u64);
i += 1;
}
table
}

pub(crate) const fn crc64_table_slice_16(width: u8, poly: u64, reflect: bool) -> [[u64; 256]; 16] {
let poly = if reflect {
let poly = poly.reverse_bits();
poly >> (64u8 - width)
} else {
poly << (64u8 - width)
};

let mut table = [[0u64; 256]; 16];
let mut i = 0;
while i < 256 {
table[0][i] = crc64(poly, reflect, i as u64);
i += 1;
}

let mut i = 0;
while i < 256 {
let mut e = 1;
while e < 16 {
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];
let mut i = 0;
while i < 256 {
let mut e = 1;
while e < $slices {
let one_lower = table[e - 1][i];

if reflect {
table[e][i] = table[0][(one_lower & 0xFF) as usize];

if BITS > 8 {
table[e][i] ^= (one_lower >> SHIFT);
}
} else {
table[e][i] = table[0][((one_lower >> (BITS - 8)) & 0xFF) as usize];

if BITS > 8 {
table[e][i] ^= (one_lower << SHIFT);
}
}
e += 1;
}
i += 1;
}
e += 1;
table
}
i += 1;
}
table
}

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

let mut table = [0u128; 256];
let mut i = 0;
while i < table.len() {
table[i] = crc128(poly, reflect, i as u128);
i += 1;
}
table
}

pub(crate) const fn crc128_table_slice_16(
width: u8,
poly: u128,
reflect: bool,
) -> [[u128; 256]; 16] {
let poly = if reflect {
let poly = poly.reverse_bits();
poly >> (128u8 - width)
} else {
poly << (128u8 - width)
};

let mut table = [[0u128; 256]; 16];
let mut i = 0;
while i < 256 {
table[0][i] = crc128(poly, reflect, i as u128);
i += 1;
}

let mut i = 0;
while i < 256 {
let mut e = 1;
while e < 16 {
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
}
impl_crc_table!(crc8_table, u8, crc8);
impl_crc_table!(crc16_table, u16, crc16);
impl_crc_table!(crc32_table, u32, crc32);
impl_crc_table!(crc64_table, u64, crc64);
impl_crc_table!(crc128_table, u128, crc128);

impl_crc_slice_table!(crc8_table_slice_16, u8, 16, crc8);
impl_crc_slice_table!(crc16_table_slice_16, u16, 16, crc16);
impl_crc_slice_table!(crc32_table_slice_16, u32, 16, crc32);
impl_crc_slice_table!(crc64_table_slice_16, u64, 16, crc64);
impl_crc_slice_table!(crc128_table_slice_16, u128, 16, crc128);