#!/bin/bash

# sendtomodelt: Send a BASIC text file to a Tandy portable over a serial port.
# At the end of the file, sends ^Z (the Tandy BASIC EOF marker).

# Why use this instead of TELCOM? Each line is tokenized as it is
# read, which saves memory. TELCOM requires downloading the entire
# text file before it can be loaded in BASIC, so enough RAM must exist
# for both the untokenized and tokenized versions simultaneously. This
# program only keeps one line of untokenized text in RAM at any time.

# Note: If you get repeated "?DS" errors and see garbled text when you
# try LIST, then it is likely that you are using a serial port on your
# PC which does not have hardware support for XON/XOFF flow control.
# Be sure to purchase a serial card or USB adapter which advertises
# "ON CHIP SOFTWARE FLOW CONTROL". Tip: an FTDI USB cable will work.

# BUGS:

# * This is a glorified one-line program with lots of error checking.
#   It ought to be just a simple 'cat $1 > /dev/ttyUSB0'.

# * And yet.... there is more that I could add that is missing. It
#   does not yet check if the serial port is writable by the user.
#   Nor does it check if the port is already open by another program.

# * Should probably give a hint to users if the tty is unwritable by
# * the user but is writable by the a group. (E.g., `sudo addgroup
# * dialout $USER` then re-login to get access. )

# * Not tested on MacOS.

#
# hackerb9, 2022

basename=$(basename $0)

usage() {
	cat >&2 <<EOF
$basename: Send a BASIC text file to a Model T portable over the serial port.
	     Each line is tokenized as it is read, which saves memory.

Usage: $basename <filename> [serial port]

Longer example:
    On Tandy Model 200/102/100, type:

	    LOAD "COM:98N1ENN"

    On UNIX host, type:

	$basename FILENAME.DO
	[wait for the Tandy to say "Ok"]
	[hit Enter to close the serial port]

    Optionally, on Tandy, type:

	    SAVE "FILENM"

EOF
}

listports() {
    shopt -s nullglob
    printf "%s\n" /dev/cu.* /dev/ttyUSB* /dev/ttyS* /dev/ttyACM* 
}


if [[ "$1" == "-h" || "$1" == "--help" ]]; then
    usage
    exit
fi

if [[ $2 ]]; then
    serial=$2
else
    serial=$(listports | head -1)
fi

if [[ ! -e $serial ]]; then
    echo "$serial does not exist. Maybe try $basename $1 /dev/ttyS0?"
    exit 1
fi


# Configure serial port the way the Tandy portables like.
#
#  ixon: Enable processing of software flow control in received data.
# ixoff: Enable sending XON/XOFF if PC gets overwhelmed by Model T (unlikely).
#  stop ^S: Use the standard software flow control character for XOFF...
# start ^Q: ... same for XON.
# -onlcr: Do not turn newlines into carriage returns on output...
# -icrnl: ... nor vice versa.
# eof ^Z: Typing a ^Z character will send an End-of-File. (Not used here).
# 19200: Bits per second ("baud rate").
#
stty -F $serial ixon ixoff  stop ^S start ^Q  -onlcr -icrnl  eof ^Z  19200

# Sidenote: Running with no filename sets up the serial port before exiting.
if [[ -z $1 ]]; then
    usage
    exit 1
fi


echo "cat $1 >$serial" >&2;
{
    cat "$1";
    echo $'\cZ';
    read -p "Hit ENTER when Model T has finished. ";
} >$serial