path: root/README
diff options
authorClifford Wolf <>2013-02-28 14:17:57 +0100
committerClifford Wolf <>2013-02-28 14:17:57 +0100
commita5c4bf2161311d73650b015b79f496651643da1e (patch)
tree2ca2e65fea59188c70f4802c626f9533e5447ddb /README
parentaf561800edc1d98c33fe057d5c02898460c9d6b9 (diff)
Added help command to README (and some other README changes)
Diffstat (limited to 'README')
1 files changed, 14 insertions, 12 deletions
diff --git a/README b/README
index 0b450ddc..3d8f46bf 100644
--- a/README
+++ b/README
@@ -23,15 +23,14 @@
yosys -- Yosys Open SYnthesis Suite
-This is a framework for RTL synthesis tools. It is highly
-experimental and under construction. The goal for now is
-to implement an extensible Verilog-2005 synthesis tool.
+This is a framework for RTL synthesis tools. It currently has
+extensive Verilog-2005 support and provides a basic set of
+synthesis algorithms for various application domains.
-The aim of this tool is to generate valid logic netlists
-from HDL designs in a manner that allows for easy addition
-of extra synthesis passes. This tool does not aim at generating
-efficient logic netlists. This can be done by passing the
-output of Yosys to a low-level synthesis tool such as ABC.
+Yosys can be adapted to perform any synthesis job by combining
+the existing passes (algorithms) using synthesis scripts and
+adding additional passes as needed by extending the yosys c++
Yosys is free software licensed under the ISC license (a GPL
compatible licence that is similar in terms to the MIT license
@@ -59,6 +58,11 @@ a simple synthesis job using the interactive command shell:
$ ./yosys
+the command "help" can be used to pritn a list of all available
+commands and "help <command>" to print details on the specified command:
+ yosys> help help
reading the design using the verilog frontend:
yosys> read_verilog tests/simple/fiedler-cooley.v
@@ -127,7 +131,7 @@ synthesis script will synthesize for the given cell library:
hierarchy; proc; memory; opt; fsm; opt
# mapping to internal cell library
- techmap
+ techmap; opt
# mapping flip-flops to mycells.lib
dfflibmap -liberty mycells.lib
@@ -213,13 +217,11 @@ TODOs / Open Bugs
- Additional internal cell types: $pla and $lut
-- Subsystem for selecting stuff (and limiting scope of passes)
- Support for registering designs (as collection of modules) to CellTypes
- Kernel support for collections of cells (from input/output cones, etc)
- Smarter resource sharing pass (add MUXes and get rid of duplicated cells)
-- Better FSM state encoding and technology mapping
+- Better FSM state encoding