update

pub fn update(self: *Wyhash, input: []const u8) void {
    self.total_len += input.len;

    if (input.len <= 48 - self.buf_len) {
        @memcpy(self.buf[self.buf_len..][0..input.len], input);
        self.buf_len += input.len;
        return;
    }

    var i: usize = 0;

    if (self.buf_len > 0) {
        i = 48 - self.buf_len;
        @memcpy(self.buf[self.buf_len..][0..i], input[0..i]);
        self.round(&self.buf);
        self.buf_len = 0;
    }

    while (i + 48 < input.len) : (i += 48) {
        self.round(input[i..][0..48]);
    }

    const remaining_bytes = input[i..];
    if (remaining_bytes.len < 16 and i >= 48) {
        const rem = 16 - remaining_bytes.len;
        @memcpy(self.buf[self.buf.len - rem ..], input[i - rem .. i]);
    }
    @memcpy(self.buf[0..remaining_bytes.len], remaining_bytes);
    self.buf_len = remaining_bytes.len;
}