Method write

serial_buffer/src/lib.rs:48–94

(&mut self, buf: &[u8])

impl Write for SerialBuffer {
    fn write(&mut self, buf: &[u8]) -> Result<usize, std::io::Error> {
        // Simply fill the buffer if we're not allowed to write to the out
        // device.
        if !self.write_out.load(Ordering::Acquire) {
            self.fill_buffer(buf);
            return Ok(buf.len());
        }

        // In case we're allowed to write to the out device, we flush the
        // content of the buffer.
        self.flush()?;

        // If after flushing the buffer, it's still not empty, that means
        // only a subset of the bytes was written and we should fill the buffer
        // with what's coming from the serial.
        if !self.buffer.is_empty() {
            self.fill_buffer(buf);
            return Ok(buf.len());
        }

        // We reach this point if we're allowed to write to the out device
        // and we know there's nothing left in the buffer.
        let mut offset = 0;
        loop {
            match self.out.write(&buf[offset..]) {
                Ok(written_bytes) => {
                    if written_bytes < buf.len() - offset {
                        offset += written_bytes;
                        continue;
                    }
                }
                Err(e) => {
                    if !matches!(e.kind(), std::io::ErrorKind::WouldBlock) {
                        return Err(e);
                    }
                    self.fill_buffer(&buf[offset..]);
                }
            }
            break;
        }

        // Make sure we flush anything that might have been written to the
        // out device.
        self.out.flush()?;

        Ok(buf.len())
    }

    // This function flushes the content of the buffer to the out device if
    // it is allowed to, otherwise this is a no-op.