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tools/pyboard.py: ProcessToSerial cross-platform fix #8435

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tools/pyboard.py: ProcessToSerial cross-platform fix #8435

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1ce0d10
tools/pyboard.py: ProcessToSerial cross-platform fix
vikmal-sw Mar 21, 2022
0e16b2e
tools/pyboard.py: Creating 2 separate classes for ProcessToSerial
vikmal-sw Mar 24, 2022
6889dde
tools/pyboard.py: Keep ProcessToSerial class in global scope
vikmal-sw Apr 4, 2022
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74 changes: 69 additions & 5 deletions tools/pyboard.py
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Original file line number Diff line number Diff line change
Expand Up @@ -153,13 +153,72 @@ def inWaiting(self):
else:
return n_waiting

# A thread that constantly reads from subp stdout and puts data into a queue (FIFO list)
# When tested, it reads double '\r' which messes up the further code, so if double '\r' detected, skip one
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Do you understand why it reads double \r?

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I have tried to investigate the reason, but unfortunately I am still not able to understand why it reads double \r

def read_stream(stream, q):
data_prec = b""
while True:
data = stream.read(1)
if (data_prec == data) and (data_prec == b'\r'):
continue
else:
q.put(data)
data_prec = data

class ProcessToSerial:
"Execute a process and emulate serial connection using its stdin/stdout."
class ProcessToSerialThreading:
"Execute a process and emulate serial connection using its stdin/stdout. Communication with stdout is done through the read_stream thread"

def __init__(self, cmd):
def __init__(self, cmd):
import subprocess

# On Windows, preexec_fn parameter should be replaced by start_new_session
self.subp = subprocess.Popen(
cmd,
bufsize=0,
shell=True,
start_new_session=True,
stdin=subprocess.PIPE,
stdout=subprocess.PIPE,
)

# On Windows, select can not be used, a thread is used instead
# that constantly reads from subp.stdout and completes a queue
import threading
import queue
self.q = queue.Queue()
self.t = threading.Thread(target=read_stream, args=(self.subp.stdout, self.q))
self.t.daemon=True # Makes thread exit when main script exits
self.t.start()

def close(self):
import signal
os.kill(self.subp.pid, signal.SIGTERM)

def read(self, size=1):
data = b""
# On Windows, data will be read from the queue that is completed by the thread
i = 0
while i != size:
data += self.q.get()
i += 1
return data

def write(self, data):
self.subp.stdin.write(data)
return len(data)

def inWaiting(self):
if self.q.empty():
return 0
else:
return 1

class ProcessToSerialPosix:
"Execute a process and emulate serial connection using its stdin/stdout. Using select to check if any data available on stdout"

def __init__(self, cmd):
import subprocess

self.subp = subprocess.Popen(
cmd,
bufsize=0,
Expand All @@ -168,7 +227,7 @@ def __init__(self, cmd):
stdin=subprocess.PIPE,
stdout=subprocess.PIPE,
)

# Initially was implemented with selectors, but that adds Python3
# dependency. However, there can be race conditions communicating
# with a particular child process (like QEMU), and selectors may
Expand All @@ -185,7 +244,6 @@ def __init__(self, cmd):

def close(self):
import signal

os.killpg(os.getpgid(self.subp.pid), signal.SIGTERM)

def read(self, size=1):
Expand All @@ -205,6 +263,12 @@ def inWaiting(self):
return 1
return 0

# Class selector based on select module platform dependancy (available on Unix, but not on Windows)
import select
if hasattr(select, "poll"):
ProcessToSerial = ProcessToSerialPosix
else:
ProcessToSerial = ProcessToSerialThreading

class ProcessPtyToTerminal:
"""Execute a process which creates a PTY and prints slave PTY as
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