videostream: add single chopper

diff --git a/misoclib/videostream/downscaler.py b/misoclib/videostream/downscaler.py
index 0b15340d2bebc94fcace678dde768d8f7f23d194..27d42b57a038f19ed74477dd0b59e4b4f1d319ac 100644 (file)
--- a/misoclib/videostream/downscaler.py
+++ b/misoclib/videostream/downscaler.py
@@ -5,6 +5,37 @@ from migen.genlib.misc import optree
 from migen.sim.generic import run_simulation
 
 class Chopper(Module):
+       def __init__(self, frac_bits):
+               self.p = Signal(frac_bits)
+               self.q = Signal(frac_bits)
+               self.chopper = Signal()
+
+               ###
+
+               acc = Signal(frac_bits)
+               self.sync += If(acc + self.p >= Cat(self.q, 0), # FIXME
+                               acc.eq(acc + self.p - self.q),
+                               self.chopper.eq(1)
+                       ).Else(
+                               acc.eq(acc + self.p),
+                               self.chopper.eq(0)
+                       )
+
+class _ChopperTB(Module):
+       def __init__(self):
+               self.submodules.dut = Chopper(16)
+               self.comb += self.dut.p.eq(320), self.dut.q.eq(681)
+
+       def gen_simulation(self, selfp):
+               yield
+               ones = 0
+               niter = 681
+               for i in range(niter):
+                       ones += selfp.dut.chopper
+                       yield
+               print("Ones: {} (expected: {})".format(ones, selfp.dut.p*niter//selfp.dut.q))
+
+class MultiChopper(Module):
        def __init__(self, N, frac_bits):
                self.init = Signal()
                self.ready = Signal()
@@ -95,6 +126,42 @@ class Chopper(Module):
                # initialize Np
                fsm.act(N, load_np.eq(1))
 
+def _count_ones(n):
+       r = 0
+       while n:
+               if n & 1:
+                       r += 1
+               n >>= 1
+       return r
+
+class _MultiChopperTB(Module):
+       def __init__(self):
+               self.submodules.dut = MultiChopper(4, 16)
+
+       def gen_simulation(self, selfp):
+               dut = selfp.dut
+
+               print("initializing chopper...")
+               dut.init = 1
+               dut.p = 320
+               dut.q = 681
+               yield
+               dut.init = 0
+               yield
+               while not dut.ready:
+                       yield
+               print("done")
+
+               dut.next = 1
+               yield
+               ones = 0
+               niter = 681
+               for i in range(niter):
+                       #print("{:04b}".format(dut.chopper))
+                       ones += _count_ones(dut.chopper)
+                       yield
+               print("Ones: {} (expected: {})".format(ones, dut.p*niter*4//dut.q))
+
 class Compacter(Module):
        def __init__(self, base_layout, N):
                self.i = Record([("w"+str(i), base_layout) for i in range(N)])
@@ -148,42 +215,6 @@ class Packer(Module):
                                [getattr(self.o, "w"+str(i)).eq(getattr(buf, "w"+str(i))) for i in range(N)]
                        )
 
-def _count_ones(n):
-       r = 0
-       while n:
-               if n & 1:
-                       r += 1
-               n >>= 1
-       return r
-
-class _ChopperTB(Module):
-       def __init__(self):
-               self.submodules.dut = Chopper(4, 16)
-
-       def gen_simulation(self, selfp):
-               dut = selfp.dut
-
-               print("initializing chopper...")
-               dut.init = 1
-               dut.p = 320
-               dut.q = 681
-               yield
-               dut.init = 0
-               yield
-               while not dut.ready:
-                       yield
-               print("done")
-
-               dut.next = 1
-               yield
-               ones = 0
-               niter = 681
-               for i in range(niter):
-                       #print("{:04b}".format(dut.chopper))
-                       ones += _count_ones(dut.chopper)
-                       yield
-               print("Ones: {} (expected: {})".format(ones, dut.p*niter*4//dut.q))
-
 class _CompacterPackerTB(Module):
        def __init__(self, input_it):
                self.input_it = input_it
@@ -221,6 +252,9 @@ if __name__ == "__main__":
        print("*** Testing chopper ***")
        run_simulation(_ChopperTB())
 
+       print("*** Testing multichopper ***")
+       run_simulation(_MultiChopperTB())
+
        print("*** Testing compacter and packer ***")
        test_seq = [
                (42, 0), (32, 1), ( 4, 1), (21, 0),