union Hasher [src]

Fields

raw: void
gzip: struct { crc: std.hash.Crc32 = .init(), count: u32 = 0, }
zlib: std.hash.Adler32
Members

container (Function)
init (Function)
update (Function)
writeFooter (Function)
Source

  pub const Hasher = union(Container) {
    raw: void,
    gzip: struct {
        crc: std.hash.Crc32 = .init(),
        count: u32 = 0,
    },
    zlib: std.hash.Adler32,

    pub fn init(containter: Container) Hasher {
        return switch (containter) {
            .gzip => .{ .gzip = .{} },
            .zlib => .{ .zlib = .{} },
            .raw => .raw,
        };
    }

    pub fn container(h: Hasher) Container {
        return h;
    }

    pub fn update(h: *Hasher, buf: []const u8) void {
        switch (h.*) {
            .raw => {},
            .gzip => |*gzip| {
                gzip.update(buf);
                gzip.count +%= buf.len;
            },
            .zlib => |*zlib| {
                zlib.update(buf);
            },
            inline .gzip, .zlib => |*x| x.update(buf),
        }
    }

    pub fn writeFooter(hasher: *Hasher, writer: *std.Io.Writer) std.Io.Writer.Error!void {
        var bits: [4]u8 = undefined;
        switch (hasher.*) {
            .gzip => |*gzip| {
                // GZIP 8 bytes footer
                //  - 4 bytes, CRC32 (CRC-32)
                //  - 4 bytes, ISIZE (Input SIZE) - size of the original (uncompressed) input data modulo 2^32
                std.mem.writeInt(u32, &bits, gzip.final(), .little);
                try writer.writeAll(&bits);

                std.mem.writeInt(u32, &bits, gzip.bytes_read, .little);
                try writer.writeAll(&bits);
            },
            .zlib => |*zlib| {
                // ZLIB (RFC 1950) is big-endian, unlike GZIP (RFC 1952).
                // 4 bytes of ADLER32 (Adler-32 checksum)
                // Checksum value of the uncompressed data (excluding any
                // dictionary data) computed according to Adler-32
                // algorithm.
                std.mem.writeInt(u32, &bits, zlib.final, .big);
                try writer.writeAll(&bits);
            },
            .raw => {},
        }
    }
}  