Minimal XMODEM sender

main.rs

use std::io::{Read, Write};

use anyhow::{anyhow, bail, Result};
use libftdi1_sys as ffi;

const ACK: u8 = 0x06;
const NAK: u8 = 0x15;
const SUB: u8 = 0x1A;
const EOT: u8 = 0x04;

fn main() -> Result<()> {
    let mut device = ftdi::find_by_vid_pid(0x0403, 0x6011)
        .interface(ftdi::Interface::A)
        .open()?;

    device.usb_reset()?;
    device.configure(
        ftdi::Bits::Eight,
        ftdi::StopBits::One,
        ftdi::Parity::None,
    )?;
    device.usb_purge_buffers()?;
    device.set_write_chunksize(64);
    device.set_read_chunksize(64);
    device.set_baud_rate(3_000_000)?;
    device.set_latency_timer(2)?;
    device.set_flow_control(ftdi::FlowControl::RtsCts)?;
    device.set_bitmode(0xFF, ftdi::BitMode::Reset)?;

    let result = unsafe {
        // Not sure if this is needed!
        (*device.libftdi_context()).usb_read_timeout = 1000;
        (*device.libftdi_context()).usb_write_timeout = 1000;
        ffi::ftdi_setdtr_rts(device.libftdi_context(), 1, 1)
    };
    if result != 0 {
        bail!("Could not set DTR / RTS");
    }

    let filename = std::env::args()
        .nth(1)
        .ok_or_else(|| anyhow!("Missing filename"))?;
    let data = std::fs::read(filename)?;

    loop {
        let mut c = vec![0u8];
        if device.read_exact(&mut c).is_ok() {
            match c[0] as char {
                'C' => break,
                c => bail!("Invalid start char '{}'", c),
            }
        }
    }

    for (i, chunk) in data.chunks(1024).enumerate() {
        if i % 100 == 0 {
            print!(" Sending {}/{}\r", i, (data.len() + 1023) / 1024);
        }

        let packet_num = (i + 1) as u8;
        let mut packet = vec![0x02, packet_num, 0xFF - packet_num];

        let mut crc = 0u16;
        for b in chunk.iter().chain(std::iter::repeat(&SUB)).take(1024) {
            packet.push(*b);
            crc = update_crc(*b, crc);
        }

        crc = update_crc(0, update_crc(0, crc));
        packet.push((crc >> 8) as u8); // CRC
        packet.push(crc as u8);

        device.write_all(&packet)?;

        let mut ack = [0u8];
        let mut okay = false;
        for _ in 0..1000 {
            let _ = device.read_exact(&mut ack);
            match ack[0] {
                ACK => {
                    okay = true;
                    break;
                }
                NAK => bail!("Got NAK"),
                _ => continue, //bail!("Got unknown ack {}", i),
            }
        }
        if !okay {
            bail!("Missed NAK");
        }
    }
    device.write_all(&[EOT])?;
    println!("\nDONE");
    Ok(())
}

/* crctab calculated by Mark G. Mendel, Network Systems Corporation */
const CRCTAB: [u16; 256] = [
    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7, 0x8108,
    0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, 0x1231, 0x0210,
    0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6, 0x9339, 0x8318, 0xb37b,
    0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de, 0x2462, 0x3443, 0x0420, 0x1401,
    0x64e6, 0x74c7, 0x44a4, 0x5485, 0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee,
    0xf5cf, 0xc5ac, 0xd58d, 0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6,
    0x5695, 0x46b4, 0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d,
    0xc7bc, 0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
    0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b, 0x5af5,
    0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12, 0xdbfd, 0xcbdc,
    0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a, 0x6ca6, 0x7c87, 0x4ce4,
    0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41, 0xedae, 0xfd8f, 0xcdec, 0xddcd,
    0xad2a, 0xbd0b, 0x8d68, 0x9d49, 0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13,
    0x2e32, 0x1e51, 0x0e70, 0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a,
    0x9f59, 0x8f78, 0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e,
    0xe16f, 0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
    0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e, 0x02b1,
    0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256, 0xb5ea, 0xa5cb,
    0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d, 0x34e2, 0x24c3, 0x14a0,
    0x0481, 0x7466, 0x6447, 0x5424, 0x4405, 0xa7db, 0xb7fa, 0x8799, 0x97b8,
    0xe75f, 0xf77e, 0xc71d, 0xd73c, 0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657,
    0x7676, 0x4615, 0x5634, 0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9,
    0xb98a, 0xa9ab, 0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882,
    0x28a3, 0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
    0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92, 0xfd2e,
    0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9, 0x7c26, 0x6c07,
    0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1, 0xef1f, 0xff3e, 0xcf5d,
    0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8, 0x6e17, 0x7e36, 0x4e55, 0x5e74,
    0x2e93, 0x3eb2, 0x0ed1, 0x1ef0,
];

/*
 * updcrc macro derived from article Copyright (C) 1986 Stephen Satchell.
 *  NOTE: First srgument must be in range 0 to 255.
 *        Second argument is referenced twice.
 *
 * Programmers may incorporate any or all code into their programs,
 * giving proper credit within the source. Publication of the
 * source routines is permitted so long as proper credit is given
 * to Stephen Satchell, Satchell Evaluations and Chuck Forsberg,
 * Omen Technology.
 */
fn update_crc(cp: u8, crc: u16) -> u16 {
    CRCTAB[((crc >> 8) & 255) as usize] ^ (crc << 8) ^ (cp as u16)
}