You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: spsc.rs
    path of file: ./repos/rio/teletypewriter/src/windows
    
    the code of the file until where you have to start completion: // Single-producer single-consumer buffer for Rust

use std::c
    
    pub fn write_from_slice(&mut self, buf: &[u8]) -> usize {
        use std::cmp::min;

        let ringbuf: &mut Box<[u8]> = unsafe { mem::transmute(self.buffer.buf.get()) };

        let ringbuf_capacity = ringbuf.len();
        let ringbuf_len = self.buffer.len.load(Ordering::SeqCst);

        // Max number of bytes we might read
        let max_write_size = min(buf.len(), ringbuf_capacity - ringbuf_len);
        let space_until_end = ringbuf_capacity - self.end;
        let write_size = min(max_write_size, space_until_end);

        ringbuf[self.end..self.end + write_size].copy_from_slice(&buf[..write_size]);
        self.end = (self.end + write_size) % ringbuf_capacity;
        self.buffer.len.fetch_add(write_size, Ordering::SeqCst);

        write_size
    }