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| author | whitequark <whitequark@whitequark.org> | 2019-07-16 20:57:05 +0000 |
|---|---|---|
| committer | whitequark <whitequark@whitequark.org> | 2019-07-16 21:00:09 +0000 |
| commit | 4ff44d85a5cb63c7b3f67c2f2398e62db7f199eb (patch) | |
| tree | 536cba16037cc59b32c3a8fc6a64181d43a2f5cd | |
| parent | f8e470c1d1178680034a28a9f28b161acf667701 (diff) | |
| download | yosys-4ff44d85a5cb63c7b3f67c2f2398e62db7f199eb.tar.gz yosys-4ff44d85a5cb63c7b3f67c2f2398e62db7f199eb.tar.bz2 yosys-4ff44d85a5cb63c7b3f67c2f2398e62db7f199eb.zip | |
write_verilog: dump zero width constants correctly.
Before this commit, zero width constants were dumped as "" (empty
string). Unfortunately, 1364-2005 5.2.3.3 indicates that an empty
string is equivalent to "\0", and is 8 bits wide, so that's wrong.
After this commit, a replication operation with a count of zero is
used instead, which is explicitly permitted per 1364-2005 5.1.14,
and is defined to have size zero. (Its operand has to have a non-zero
size for it to be legal, though.)
Fixes #948 (again).
| -rw-r--r-- | backends/verilog/verilog_backend.cc | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/backends/verilog/verilog_backend.cc b/backends/verilog/verilog_backend.cc index a020d82b6..48404b34c 100644 --- a/backends/verilog/verilog_backend.cc +++ b/backends/verilog/verilog_backend.cc @@ -189,7 +189,8 @@ void dump_const(std::ostream &f, const RTLIL::Const &data, int width = -1, int o if (width < 0) width = data.bits.size() - offset; if (width == 0) { - f << "\"\""; + // See IEEE 1364-2005 Clause 5.1.14. + f << "{0{1'b0}}"; return; } if (nostr) |