migen/genlib/misc: add reverse_bytes

migen/genlib/misc.py

@@ -1,3 +1,5 @@
+import math
+
 from migen.fhdl.std import *
 from migen.fhdl.structure import _Operator
 
@@ -64,6 +66,14 @@ def chooser(signal, shift, output, n=None, reverse=False):
     return Case(shift, cases).makedefault()
 
 
+def reverse_bytes(signal):
+    n = math.ceil(flen(signal)/8)
+    r = []
+    for i in reversed(range(n)):
+        r.append(signal[i*8:min((i+1)*8, flen(signal))])
+    return Cat(iter(r))
+
+
 def timeline(trigger, events):
     lastevent = max([e[0] for e in events])
     counter = Signal(max=lastevent+1)