From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Wed, 26 Feb 2020 17:52:06 +0000 (+0000)
Subject: more fun comments
X-Git-Tag: ls180-24jan2020~113
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=8694385463d9ebf0cf476e89b997a88f5dd9c91f;p=ieee754fpu.git

more fun comments
---

diff --git a/src/ieee754/part_shift/part_shift_dynamic.py b/src/ieee754/part_shift/part_shift_dynamic.py
index e04083a2..5e2c4406 100644
--- a/src/ieee754/part_shift/part_shift_dynamic.py
+++ b/src/ieee754/part_shift/part_shift_dynamic.py
@@ -206,11 +206,19 @@ class PartitionedDynamicShift(Elaboratable):
         for i in range(1, len(keys)):
             element = Mux(gates[i-1], masked_b[i], element)
             b_shl_amount.append(element) # FIXME: creates an O(N^2) cascade
+            # TODO: store result of Mux in a Signal of the correct width
+            # then append *that* into b_shl_amount
+
+        # because the right-shift input is reversed, we have to also
+        # reverse the *order* of the shift amounts (not the bits *in* the
+        # shift amounts)
         b_shr_amount = list(reversed(b_shl_amount))
 
         # select shift-amount (b) for partition based on op being left or right
         shift_amounts = []
         for i in range(len(b_shl_amount)):
+            # FIXME: all signals (with very few exceptions) have to be
+            # reset_less
             shift_amount = Signal(masked_b[i].width, name="shift_amount%d" % i)
             sel = Mux(self.shift_right, b_shr_amount[i], b_shl_amount[i])
             comb += shift_amount.eq(sel)