88 lines
2.9 KiB
Python
88 lines
2.9 KiB
Python
##
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## **** PTY_Interface Class ****
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## by Aidan Macdonald (aidan.plenert.macdonald@gmail.com)
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##
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## This class generates a pty device that emulates the
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## tty device created by GPIB controllers such as
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## Prologix GPIB-USB Controller (prologix.biz)
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##
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## This class does NOT emulate the controller, but the
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## controller must be attached to this PTY Interface
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##
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## I may switch between the terms tty device and pty device.
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## They refer to the same thing.
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##
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import os
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import Device, Prologix
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class Interface:
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##%% Initialization - Interface(default_device, default_address)
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## accepts arguments default_device and default_address
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## the default_device will be connected at the default_address
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##
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## If the Interface address (PTY_Interface.addr) is changed, the
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## no longer have anything attached and will become functionless.
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## UNLESS, the default device handles the address change and copies itself
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## to the new address (Prologix_GPIB_USB does this, OR there is
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## another device attached there.
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##
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## if no arguments are given at initialization, defaults are
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## Device.Prologix_GPIB-USB at address 0
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##
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def __init__(self,
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default_device=Prologix.Prologix_GPIB_USB(),
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default_address=0 ):
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self.m, self.s = os.openpty()
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self.devices = {default_address:default_device}
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self.addr = default_address
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##%% printFilename()
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## Prints the path to the PTY device generated (ie /dev/pts/2)
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##
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def printFilename(self):
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name = os.ttyname(self.s)
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print(name)
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return name
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##%% run(readLen)
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## Runs the emulator which will read all statements written from the outside
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## to the pty device at the location given by self.printFilename(), then
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## runs what was read through self.handleInput(tty_in) and writes output
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## back to the pty device to be read from the outside
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##
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def run(self, readLen=100):
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self.running = True
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while (self.running):
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tty_in = os.read(self.m, readLen)
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for tty_out in self.handleInput(tty_in):
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os.write(self.m, tty_out.encode())
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##%% handleInput(tty_in)
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## Recieves raw input that was read from the pty device, and
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## breaks it up and send it to the device listed at the current
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## address. That device must handle the command via dev.handleCMD(cmd, args)
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##
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def handleInput(self, tty_in):
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tty_in = tty_in.strip().decode()
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if tty_in != "" and self.addr in self.devices:
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dev = self.devices[self.addr]
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for cmd in tty_in.strip().split(";"):
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p = cmd.strip().split(" ")
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yield dev.handleCMD(self, p[0], p[1:]) + "\n"
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yield "" # Must be a null string to prevent infinite loop
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##%% addDevice(device, address)
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## Preferred way of connecting a device to the interface
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## at a given address
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##
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def addDevice(self, dev, addr):
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self.devices[addr] = dev
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