From: Sebastien Bourdeauducq <sebastien@milkymist.org>
Date: Thu, 8 Mar 2012 19:49:24 +0000 (+0100)
Subject: fhdl: handle negative constants correctly
X-Git-Tag: 24jan2021_ls180~2099^2~978
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=bfcd4e636be832e657bcf8639ccb68e29fd8d666;p=litex.git

fhdl: handle negative constants correctly
---

diff --git a/migen/fhdl/structure.py b/migen/fhdl/structure.py
index 69f53f65..748ea059 100644
--- a/migen/fhdl/structure.py
+++ b/migen/fhdl/structure.py
@@ -8,7 +8,9 @@ def bits_for(n):
 	if isinstance(n, Constant):
 		return n.bv.width
 	else:
-		if n == 0:
+		if n < 0:
+			return bits_for(-n) + 1
+		elif n == 0:
 			return 1
 		else:
 			return int(math.ceil(math.log(n+1, 2)))
@@ -118,7 +120,7 @@ class Replicate(Value):
 
 class Constant(Value):
 	def __init__(self, n, bv=None):
-		self.bv = bv or BV(bits_for(n))
+		self.bv = bv or BV(bits_for(n), n < 0)
 		self.n = n
 	
 	def __repr__(self):