From 9fd4594c5363954f58122418f8f51a320392f747 Mon Sep 17 00:00:00 2001
From: Robert Jordens <jordens@gmail.com>
Date: Sun, 5 Apr 2015 04:32:23 -0600
Subject: [PATCH] interpolate: refactor discrete_compensate

---
 artiq/devices/pdq2/driver.py       | 23 ++++++++---------------
 artiq/wavesynth/compute_samples.py |  8 +-------
 artiq/wavesynth/interpolate.py     | 10 +++++++++-
 3 files changed, 18 insertions(+), 23 deletions(-)

diff --git a/artiq/devices/pdq2/driver.py b/artiq/devices/pdq2/driver.py
index c6d3ad566..851adb5c8 100644
--- a/artiq/devices/pdq2/driver.py
+++ b/artiq/devices/pdq2/driver.py
@@ -6,13 +6,16 @@ import struct
 
 import serial
 
+from artiq.wavesynth.interpolate import discrete_compensate
+
+
 logger = logging.getLogger(__name__)
 
 
 class Segment:
     max_time = 1 << 16  # uint16 timer
     max_val = 1 << 15  # int16 DAC
-    max_out = 10. # Volt
+    max_out = 10.  # Volt
     out_scale = max_val/max_out
     cordic_gain = 1.
     for i in range(16):
@@ -53,24 +56,13 @@ class Segment:
                          values, widths, ud, fmt, e)
             raise e
 
-    @staticmethod
-    def compensate(coef):
-        """compensates higher order spline coefficients for integrator chain
-        latency"""
-        order = len(coef)
-        if order > 2:
-            coef[1] += coef[2]/2.
-        if order > 3:
-            coef[1] += coef[3]/6.
-            coef[2] += coef[3]
-        return coef
-
     def bias(self, amplitude=[], **kwargs):
         """Append a bias line to this segment.
 
         Amplitude in volts
         """
-        coef = self.compensate([self.out_scale*a for a in amplitude])
+        coef = [self.out_scale*a for a in amplitude]
+        discrete_compensate(coef)
         data = self.pack([0, 1, 2, 2], coef)
         self.line(typ=0, data=data, **kwargs)
 
@@ -83,7 +75,8 @@ class Segment:
         phase[2] in turns*(sample_rate/2**shift)**2
         """
         scale = self.out_scale/self.cordic_gain
-        coef = self.compensate([scale*a for a in amplitude])
+        coef = [scale*a for a in amplitude]
+        discrete_compensate(coef)
         if phase:
             assert len(amplitude) == 4
         coef += [p*self.max_val*2 for p in phase]
diff --git a/artiq/wavesynth/compute_samples.py b/artiq/wavesynth/compute_samples.py
index 31a345480..debe393a6 100644
--- a/artiq/wavesynth/compute_samples.py
+++ b/artiq/wavesynth/compute_samples.py
@@ -1,13 +1,7 @@
 from copy import copy
 from math import cos, pi
 
-
-def discrete_compensate(c):
-    if len(c) > 2:
-        c[1] += c[2]/2
-    if len(c) > 3:
-        c[1] += c[3]/6
-        c[2] += c[3]
+from artiq.wavesynth.interpolate import discrete_compensate
 
 
 class Spline:
diff --git a/artiq/wavesynth/interpolate.py b/artiq/wavesynth/interpolate.py
index 39cdf4bf0..8e133c1c7 100644
--- a/artiq/wavesynth/interpolate.py
+++ b/artiq/wavesynth/interpolate.py
@@ -23,7 +23,15 @@ def _interpolate(time, data, sample_times, order=3):
     return coeffs
 
 
-def _zip_program(times, channels, target=):
+def discrete_compensate(c):
+    if len(c) > 2:
+        c[1] += c[2]/2
+    if len(c) > 3:
+        c[1] += c[3]/6
+        c[2] += c[3]
+
+
+def _zip_program(times, channels, target):
     for tc in zip(times, *channels):
         yield {
             "duration": tc[0],