const std = @import("../std.zig");
const builtin = @import("builtin");
const debug = std.debug;
const testing = std.testing;
pub usingnamespace @import("crc/catalog.zig");
pub fn Algorithm(comptime W: type) type {
return struct {
polynomial: W,
initial: W,
reflect_input: bool,
reflect_output: bool,
xor_output: W,
};
}
pub fn Crc(comptime W: type, comptime algorithm: Algorithm(W)) type {
return struct {
const Self = @This();
const I = if (@bitSizeOf(W) < 8) u8 else W;
const lookup_table = blk: {
@setEvalBranchQuota(2500);
const poly = if (algorithm.reflect_input)
@bitReverse(@as(I, algorithm.polynomial)) >> (@bitSizeOf(I) - @bitSizeOf(W))
else
@as(I, algorithm.polynomial) << (@bitSizeOf(I) - @bitSizeOf(W));
var table: [256]I = undefined;
for (&table, 0..) |*e, i| {
var crc: I = i;
if (algorithm.reflect_input) {
var j: usize = 0;
while (j < 8) : (j += 1) {
crc = (crc >> 1) ^ ((crc & 1) * poly);
}
} else {
crc <<= @bitSizeOf(I) - 8;
var j: usize = 0;
while (j < 8) : (j += 1) {
crc = (crc << 1) ^ (((crc >> (@bitSizeOf(I) - 1)) & 1) * poly);
}
}
e.* = crc;
}
break :blk table;
};
crc: I,
pub fn init() Self {
const initial = if (algorithm.reflect_input)
@bitReverse(@as(I, algorithm.initial)) >> (@bitSizeOf(I) - @bitSizeOf(W))
else
@as(I, algorithm.initial) << (@bitSizeOf(I) - @bitSizeOf(W));
return Self{ .crc = initial };
}
inline fn tableEntry(index: I) I {
return lookup_table[@intCast(u8, index & 0xFF)];
}
pub fn update(self: *Self, bytes: []const u8) void {
var i: usize = 0;
if (@bitSizeOf(I) <= 8) {
while (i < bytes.len) : (i += 1) {
self.crc = tableEntry(self.crc ^ bytes[i]);
}
} else if (algorithm.reflect_input) {
while (i < bytes.len) : (i += 1) {
const table_index = self.crc ^ bytes[i];
self.crc = tableEntry(table_index) ^ (self.crc >> 8);
}
} else {
while (i < bytes.len) : (i += 1) {
const table_index = (self.crc >> (@bitSizeOf(I) - 8)) ^ bytes[i];
self.crc = tableEntry(table_index) ^ (self.crc << 8);
}
}
}
pub fn final(self: Self) W {
var c = self.crc;
if (algorithm.reflect_input != algorithm.reflect_output) {
c = @bitReverse(c);
}
if (!algorithm.reflect_output) {
c >>= @bitSizeOf(I) - @bitSizeOf(W);
}
return @intCast(W, c ^ algorithm.xor_output);
}
pub fn hash(bytes: []const u8) W {
var c = Self.init();
c.update(bytes);
return c.final();
}
};
}
pub const Polynomial = enum(u32) {
IEEE = 0xedb88320,
Castagnoli = 0x82f63b78,
Koopman = 0xeb31d82e,
_,
};
pub const Crc32 = Crc32WithPoly(.IEEE);
pub fn Crc32WithPoly(comptime poly: Polynomial) type {
return struct {
const Self = @This();
const lookup_tables = block: {
@setEvalBranchQuota(20000);
var tables: [8][256]u32 = undefined;
for (&tables[0], 0..) |*e, i| {
var crc = @intCast(u32, i);
var j: usize = 0;
while (j < 8) : (j += 1) {
if (crc & 1 == 1) {
crc = (crc >> 1) ^ @enumToInt(poly);
} else {
crc = (crc >> 1);
}
}
e.* = crc;
}
var i: usize = 0;
while (i < 256) : (i += 1) {
var crc = tables[0][i];
var j: usize = 1;
while (j < 8) : (j += 1) {
const index = @truncate(u8, crc);
crc = tables[0][index] ^ (crc >> 8);
tables[j][i] = crc;
}
}
break :block tables;
};
crc: u32,
pub fn init() Self {
return Self{ .crc = 0xffffffff };
}
pub fn update(self: *Self, input: []const u8) void {
var i: usize = 0;
while (i + 8 <= input.len) : (i += 8) {
const p = input[i .. i + 8];
self.crc ^= std.mem.readIntLittle(u32, p[0..4]);
self.crc =
lookup_tables[0][p[7]] ^
lookup_tables[1][p[6]] ^
lookup_tables[2][p[5]] ^
lookup_tables[3][p[4]] ^
lookup_tables[4][@truncate(u8, self.crc >> 24)] ^
lookup_tables[5][@truncate(u8, self.crc >> 16)] ^
lookup_tables[6][@truncate(u8, self.crc >> 8)] ^
lookup_tables[7][@truncate(u8, self.crc >> 0)];
}
while (i < input.len) : (i += 1) {
const index = @truncate(u8, self.crc) ^ input[i];
self.crc = (self.crc >> 8) ^ lookup_tables[0][index];
}
}
pub fn final(self: *Self) u32 {
return ~self.crc;
}
pub fn hash(input: []const u8) u32 {
var c = Self.init();
c.update(input);
return c.final();
}
};
}
test "crc32 ieee" {
const Crc32Ieee = Crc32WithPoly(.IEEE);
try testing.expect(Crc32Ieee.hash("") == 0x00000000);
try testing.expect(Crc32Ieee.hash("a") == 0xe8b7be43);
try testing.expect(Crc32Ieee.hash("abc") == 0x352441c2);
}
test "crc32 castagnoli" {
const Crc32Castagnoli = Crc32WithPoly(.Castagnoli);
try testing.expect(Crc32Castagnoli.hash("") == 0x00000000);
try testing.expect(Crc32Castagnoli.hash("a") == 0xc1d04330);
try testing.expect(Crc32Castagnoli.hash("abc") == 0x364b3fb7);
}
pub fn Crc32SmallWithPoly(comptime poly: Polynomial) type {
return struct {
const Self = @This();
const lookup_table = block: {
var table: [16]u32 = undefined;
for (&table, 0..) |*e, i| {
var crc = @intCast(u32, i * 16);
var j: usize = 0;
while (j < 8) : (j += 1) {
if (crc & 1 == 1) {
crc = (crc >> 1) ^ @enumToInt(poly);
} else {
crc = (crc >> 1);
}
}
e.* = crc;
}
break :block table;
};
crc: u32,
pub fn init() Self {
return Self{ .crc = 0xffffffff };
}
pub fn update(self: *Self, input: []const u8) void {
for (input) |b| {
self.crc = lookup_table[@truncate(u4, self.crc ^ (b >> 0))] ^ (self.crc >> 4);
self.crc = lookup_table[@truncate(u4, self.crc ^ (b >> 4))] ^ (self.crc >> 4);
}
}
pub fn final(self: *Self) u32 {
return ~self.crc;
}
pub fn hash(input: []const u8) u32 {
var c = Self.init();
c.update(input);
return c.final();
}
};
}
test "small crc32 ieee" {
const Crc32Ieee = Crc32SmallWithPoly(.IEEE);
try testing.expect(Crc32Ieee.hash("") == 0x00000000);
try testing.expect(Crc32Ieee.hash("a") == 0xe8b7be43);
try testing.expect(Crc32Ieee.hash("abc") == 0x352441c2);
}
test "small crc32 castagnoli" {
const Crc32Castagnoli = Crc32SmallWithPoly(.Castagnoli);
try testing.expect(Crc32Castagnoli.hash("") == 0x00000000);
try testing.expect(Crc32Castagnoli.hash("a") == 0xc1d04330);
try testing.expect(Crc32Castagnoli.hash("abc") == 0x364b3fb7);
}