From: Dan White <dan@whiteaudio.com>
Date: Tue, 10 Jul 2012 18:10:17 +0000 (-0500)
Subject: clarify usbio.py function docs
X-Git-Tag: calibrations~34
X-Git-Url: http://git.whiteaudio.com/gitweb/?a=commitdiff_plain;h=9b5a3a729d1b46ef52413682100bb660e234d979;p=430.git

clarify usbio.py function docs
---

diff --git a/python-lib/usbio.py b/python-lib/usbio.py
index f632969..98517ee 100644
--- a/python-lib/usbio.py
+++ b/python-lib/usbio.py
@@ -43,6 +43,19 @@ def log2(x):
     return log(x) / log(2)
 
 def truth(v):
+    """Returns a truth value of the given value.
+
+    Allows patterns like: truth(~False) == True
+    the pythonic way is: True is not False
+    while: "True == ~False" returns False an NOT expected"
+
+    in python:
+        ~True == int(-2)
+        ~False == int(-1)
+
+    This returns v if v is a bool, returns False if v is an int and is one of
+    [0, -2], True of bool(v) is True, and False otherwise.
+    """
     if isinstance(v, (int, intbv)):
         # NB: ~True == -2
         #     ~False == -1
@@ -72,7 +85,8 @@ class I2C(object):
     def __init__(self, interface=ftdi.INTERFACE_A, scl=0, sda=1,
                     vid=0x0403, pid=0x6011, delay=0.001, timeout=100,
                     pindir=0xc0, pinstate=0xc0):
-        """Bitbanged I2C for use on FT4232H ports C and D.
+        """Bitbanged I2C for use on FT4232H ports C and D.  Uses the libftdi
+        python bindings.
 
         interface = [0,1,2,3]
         scl/sda = port pin numbers