From: Mike Walters <mike@flomp.net>
Date: Sun, 14 Jun 2020 13:42:20 +0000 (+0100)
Subject: cxxrtl: fix sshr sign-extension.
X-Git-Tag: working-ls180~472^2
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=66a2de2912604864e5d7a7717397caf814646621;p=yosys.git

cxxrtl: fix sshr sign-extension.
---

diff --git a/backends/cxxrtl/cxxrtl.h b/backends/cxxrtl/cxxrtl.h
index 2458487e1..0e2e27ed4 100644
--- a/backends/cxxrtl/cxxrtl.h
+++ b/backends/cxxrtl/cxxrtl.h
@@ -376,10 +376,12 @@ struct value : public expr_base<value<Bits>> {
 				: data[chunks - 1 - n] << (chunk::bits - shift_bits);
 		}
 		if (Signed && is_neg()) {
-			for (size_t n = chunks - shift_chunks; n < chunks; n++)
+			size_t top_chunk_idx  = (Bits - shift_bits) / chunk::bits;
+			size_t top_chunk_bits = (Bits - shift_bits) % chunk::bits;
+			for (size_t n = top_chunk_idx + 1; n < chunks; n++)
 				result.data[n] = chunk::mask;
 			if (shift_bits != 0)
-				result.data[chunks - shift_chunks] |= chunk::mask << (chunk::bits - shift_bits);
+				result.data[top_chunk_idx] |= chunk::mask << top_chunk_bits;
 		}
 		return result;
 	}