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authorClifford Wolf <clifford@clifford.at>2015-11-01 14:46:36 +0100
committerClifford Wolf <clifford@clifford.at>2015-11-01 14:46:36 +0100
commit406c2ad88f46bc5774fad55e90b45bbb02eed187 (patch)
treee3ab45032590902e009ae4c1cf905641ac0e32cd
parentdc3698753afd9c7b40a86cc86a3abb7ae00704cb (diff)
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Revert "Added heuristics to further reduce LUT equations."
This reverts commit 8447080d628d11a5571e715bfc5a6f5ba3d46e25.
-rwxr-xr-xicebox/icebox_vlog.py17
1 files changed, 5 insertions, 12 deletions
diff --git a/icebox/icebox_vlog.py b/icebox/icebox_vlog.py
index 4d1a772..4a79cd4 100755
--- a/icebox/icebox_vlog.py
+++ b/icebox/icebox_vlog.py
@@ -810,24 +810,17 @@ for lut in luts_queue:
elif not "0" in lut_bits:
const_assigns.append([net_out, "1'b1"])
else:
- def equals_1(expr):
- return (expr == "1") or (expr == "1'b1")
- def equals_0(expr):
- return (expr == "0") or (expr == "1'b0")
def make_lut_expr(bits, sigs):
if not sigs:
return "1'b%s" % bits[0]
l_expr = make_lut_expr(bits[0:len(bits)//2], sigs[1:])
h_expr = make_lut_expr(bits[len(bits)//2:len(bits)], sigs[1:])
if h_expr == l_expr: return h_expr
- if equals_0(sigs[0]): return l_expr
- if equals_1(sigs[0]): return h_expr
- if equals_1(h_expr) and equals_0(l_expr): return sigs[0]
- if equals_0(h_expr) and equals_1(l_expr): return "!" + sigs[0]
- if h_expr == "!" + l_expr: return "(%s ^ %s)" % (sigs[0], l_expr)
- if equals_0(h_expr): return "(%s & !%s)" % (sigs[0], l_expr)
- if equals_0(l_expr): return "(%s & %s)" % (sigs[0], h_expr)
- return "(%s ? %s : %s)" % (sigs[0], h_expr, l_expr)
+ if sigs[0] == "0": return l_expr
+ if sigs[0] == "1": return h_expr
+ if h_expr == "1" and l_expr == "0": return sigs[0]
+ if h_expr == "0" and l_expr == "1": return "!" + sigs[0]
+ return "%s ? %s : %s" % (sigs[0], h_expr, l_expr)
lut_expr = make_lut_expr(lut_bits, [net_in3, net_in2, net_in1, net_in0])
lut_assigns.append([net_out, "/* LUT %2d %2d %2d */ %s" % (lut[0], lut[1], lut[2], lut_expr)])
max_net_len = max(max_net_len, len(net_out))