XSCT error in pseudo terminal (pty)

[betontalpfa]

Here is a so post about this issue. I didn't get an answer.

Here is a sample wrapper for Xilinx's XSCT console. (It just echoes the XSCT answer to the console and give the commands to the XSCT)

#xsct_wrapper.py

import sys
import os
import re
import pexpect

# Path of Xilinx'XSCT executable:
xsct = '/opt/Xilinx/Vivado/2017.4/bin/xsdb'
prompt = '% '

# Start XSCT
p = pexpect.spawn(xsct)

# Wait for prompt
p.expect(prompt, timeout = 5)

# print the texts
print(p.before.decode(), end='')
print(p.match.group(0).decode(), end='')


while True:

    # Wait and run a command.
    command = input()
    p.sendline(command)
    
    try:
        # Wait for prompt
        p.expect(prompt)
        
        # print the texts
        print(p.before.decode(), end='')
        print(p.match.group(0).decode(), end='')
    
    except pexpect.EOF:
        # The program has exited
        print('The program has exied... BY!')
        break

My problem is that the answers form the XSCT are misaligned, or never arrived. Here is a snippet:

PC:~$ python3 xsct_wrapper.py
rlwrap: warning: your $TERM is 'xterm-256color' but rlwrap couldn't find it in the terminfo database. Expect some problems.

****** Xilinx System Debugger (XSDB) v2017.4
  **** Build date : Dec 15 2017-21:02:16
    ** Copyright 1986-2017 Xilinx, Inc. All Rights Reserved.


xsdb% puts hello
xsdb%                                    ((I hit enters here...))
xsdb%
xsdb% ello
xsdb%

While I started XSCT natively it works as expected:

PC:~$ /opt/Xilinx/Vivado/2017.4/bin/xsdb
rlwrap: warning: your $TERM is 'xterm-256color' but rlwrap couldn't find it in the terminfo database. Expect some problems.

****** Xilinx System Debugger (XSDB) v2017.4
  **** Build date : Dec 15 2017-21:02:16
    ** Copyright 1986-2017 Xilinx, Inc. All Rights Reserved.


xsdb% puts hello
hello
xsdb%

What do I do wrong?

(I have tried to change the executable in the wrapper from xsct to bash, then it works as expected.)

I use:

• 5.0.0-32-generic # 34~18.04.2-Ubuntu SMP Thu Oct 10 10:36:02 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
• Python 3.6.8
• pexpect==4.2.1
• Vivado 2017.4

[ibaie]

Hi @betontalpfa 

I'm not sure how does work python when creating a subprocess and neither XSCT as doing really but maybe you might want to try using xsdbserver instead. Basically you can launch XSDB server with a TCP opened to process commands and use Python as front end.

Regards

[betontalpfa]

Thanks @ibaie 

I have create a simple python wrapper called pysct on github  (based on your reply).

Here is an example code:

import pysct

win_xsct_executable = r'C:\Xilinx\SDK\2017.4\bin\xsct.bat'
xsct_server = XsctServer(win_xsct_executable, port=PORT, verbose=False)
xsct = Xsct('localhost', PORT)
    
print("xsct's pid: {}".format(xsct.do('pid')))
print(xsct.do('set a 5'))
print(xsct.do('set b 4'))
print("5+4={}".format(xsct.do('expr $a + $b')))

xsct.close()
xsct_server.stop_server()

Prints out:

xsct's pid: 13808
5
4
5+4=9