genlib/cordic: cleanup

diff --git a/migen/genlib/cordic.py b/migen/genlib/cordic.py
index b6895a2a64aafd51cbab242be99fc94a2129b22c..b52ff78ad541600e93608b9cc250e6d248400674 100644 (file)
--- a/migen/genlib/cordic.py
+++ b/migen/genlib/cordic.py
@@ -2,7 +2,6 @@ from math import atan, atanh, log, sqrt, pi
 
 from migen.fhdl.std import *
 
-
 class TwoQuadrantCordic(Module):
        """
        http://eprints.soton.ac.uk/267873/1/tcas1_cordic_review.pdf
@@ -10,7 +9,7 @@ class TwoQuadrantCordic(Module):
        def __init__(self, width=16, stages=None, guard=0,
                        eval_mode="iterative", cordic_mode="rotate",
                        func_mode="circular"):
-               # validate paramters
+               # validate parameters
                assert eval_mode in ("combinatorial", "pipelined", "iterative")
                assert cordic_mode in ("rotate", "vector")
                self.cordic_mode = cordic_mode
@@ -113,9 +112,7 @@ class TwoQuadrantCordic(Module):
                a_{m,i}: elemetary rotation angle
                """
                dx, dy, dz = xi>>i, yi>>i, a
-               # FIXME need 1'sd0 here, "Signal((n, True)) >= 0" is always true
-               # as 1'd0 makes the comparison unsigned
-               direction = {"rotate": zi[-1], "vector": ~yi[-1]}[self.cordic_mode]
+               direction = {"rotate": zi < 0, "vector": yi >= 0}[self.cordic_mode]
                dy = {"circular": dy, "linear": 0, "hyperbolic": -dy}[self.func_mode]
                ret = If(direction,
                                        xo.eq(xi + dy),
@@ -128,8 +125,6 @@ class TwoQuadrantCordic(Module):
                                )
                return ret
 
-
-
 class Cordic(TwoQuadrantCordic):
        def __init__(self, **kwargs):
                TwoQuadrantCordic.__init__(self, **kwargs)
@@ -165,7 +160,6 @@ class Cordic(TwoQuadrantCordic):
                                        self.yo.eq(-cyo),
                                )]
 
-
 class TB(Module):
        def __init__(self, n, **kwargs):
                self.submodules.cordic = Cordic(**kwargs)
@@ -189,8 +183,7 @@ class TB(Module):
                                        (self.xi, self.yi, self.zi)):
                                s.wr(r, int(v.pop(0)*c))
 
-
-def main():
+def _main():
        from migen.fhdl import verilog
        from migen.sim.generic import Simulator, TopLevel
        from matplotlib import pyplot as plt
@@ -211,8 +204,7 @@ def main():
        plt.plot(tb.zo)
        plt.show()
 
-
-def rms_err(width, stages, n):
+def _rms_err(width, stages, n):
        from migen.sim.generic import Simulator
        import numpy as np
        import matplotlib.pyplot as plt
@@ -228,8 +220,7 @@ def rms_err(width, stages, n):
        dy = tb.yo[1:]-y*2**(width-1)
        return ((dx**2+dy**2)**.5).sum()/n
 
-
-def test_err():
+def _test_err():
        from matplotlib import pyplot as plt
        import numpy as np
 
@@ -244,8 +235,7 @@ def test_err():
        plt.grid("on")
        plt.show()
 
-
 if __name__ == "__main__":
-       main()
-       #rms_err(16, 16, 345)
-       #test_err()
+       _main()
+       #_rms_err(16, 16, 345)
+       #_test_err()