add pty-gpib-emulator from github

pty-gpib-emulator/python/PTY_Interface.py

@@ -0,0 +1,87 @@
+##
+## ****  PTY_Interface Class ****
+## by Aidan Macdonald (aidan.plenert.macdonald@gmail.com)
+## 
+## This class generates a pty device that emulates the
+## tty device created by GPIB controllers such as
+## Prologix GPIB-USB Controller (prologix.biz)
+## 
+## This class does NOT emulate the controller, but the
+## controller must be attached to this PTY Interface
+## 
+## I may switch between the terms tty device and pty device.
+## They refer to the same thing.
+##
+
+
+import os
+import Device, Prologix
+
+class Interface:
+
+##%% Initialization - Interface(default_device, default_address)
+## accepts arguments default_device and default_address
+## the default_device will be connected at the default_address
+## 
+## If the Interface address (PTY_Interface.addr) is changed, the
+## no longer have anything attached and will become functionless.
+## UNLESS, the default device handles the address change and copies itself
+## to the new address (Prologix_GPIB_USB does this, OR there is
+## another device attached there.
+##
+## if no arguments are given at initialization, defaults are
+## Device.Prologix_GPIB-USB at address 0
+##
+    def __init__(self,
+                 default_device=Prologix.Prologix_GPIB_USB(),
+                 default_address=0 ):
+        self.m, self.s = os.openpty()
+        self.devices = {default_address:default_device}
+        self.addr = default_address
+
+##%% printFilename()
+## Prints the path to the PTY device generated (ie /dev/pts/2)
+##
+    def printFilename(self):
+        name = os.ttyname(self.s) 
+        print(name)
+        return name
+
+##%% run(readLen)
+## Runs the emulator which will read all statements written from the outside
+## to the pty device at the location given by self.printFilename(), then
+## runs what was read through self.handleInput(tty_in) and writes output
+## back to the pty device to be read from the outside
+##
+    def run(self, readLen=100):
+        self.running = True
+        while (self.running):
+            tty_in = os.read(self.m, readLen)
+            for tty_out in self.handleInput(tty_in):
+                os.write(self.m, tty_out)
+
+
+##%% handleInput(tty_in)
+## Recieves raw input that was read from the pty device, and 
+## breaks it up and send it to the device listed at the current
+## address. That device must handle the command via dev.handleCMD(cmd, args)
+##
+    def handleInput(self, tty_in):
+        tty_in = tty_in.strip()
+
+        if tty_in != "" and self.addr in self.devices:
+            dev = self.devices[self.addr]
+            for cmd in tty_in.strip().split(";"):
+                p = cmd.strip().split(" ")
+                yield dev.handleCMD(self, p[0], p[1:]) + "\n"
+
+        yield ""  # Must be a null string to prevent infinite loop
+
+##%% addDevice(device, address)
+## Preferred way of connecting a device to the interface
+## at a given address
+##
+    def addDevice(self, dev, addr):
+        self.devices[addr] = dev
+        
+