add bisection function for finding offset values

diff --git a/python-lib/mpsse-test.py b/python-lib/mpsse-test.py
index 33e862dd17303d5631903f207a4464f63ec1ee70..d292bcbf19654d1c3f77c2a1473720590770deea 100755 (executable)
--- a/python-lib/mpsse-test.py
+++ b/python-lib/mpsse-test.py
@@ -34,6 +34,45 @@ def str2hex(x):
     return ''.join(map(lambda h: '%02x' % ord(h), x))
 
 
+def bisect(fset, limits=[0.0, 1.0], dgmin=None):
+    """Given a one-input function fset and list of limits, interactively bisect
+    the range by sending fset(guess) and asking to go (u)p or (d)own for the
+    next step.  Each stepsize is progressively halved and optionally limited to
+    dgmin if given."""
+    xmin = min(limits)
+    xmax = max(limits)
+    g = (xmax - xmin) / 2 + xmin
+    dg = (xmax - xmin) / 4
+    last = xmin
+
+    guess = [xmin, xmax]
+
+    quit = False
+    while quit == False:
+        print 'sending guess:', g, dg
+        guess.append(g)
+        fset(g)
+
+        a = raw_input('q, [u,k], [d,j] ? ').lower()
+        if a == 'q':
+            quit = True
+            return guess[2:]
+
+        if a in 'dj':
+            g = g - dg
+        elif a in 'uk':
+            g = g + dg
+        else:
+            print 'OOPS, expecting u or d only'
+
+        dg = dg / 2
+        # for ints, step size stops at 1
+        if isinstance(xmin, int):
+            dg = max(dg, 1)
+        elif dgmin is not None and dg < dgmin:
+            dg = dgmin
+
+
 
 ##############################################################################
 # Setup FTDI serial ports