abc9_ops: -prep_hier to create unmap module that removes Q's (* init *)

[yosys.git] / CodingReadme

diff --git a/CodingReadme b/CodingReadme
index 9e85add2848ca6bc1367ab82c1d84f1e283b1aef..7d4ded93d2ffb12e88b81d0a254f6b804c6e1127 100644 (file)
--- a/CodingReadme
+++ b/CodingReadme
@@ -21,7 +21,7 @@ Here is a the C++ code for a "hello_world" Yosys command (hello.cc):
 
        struct HelloWorldPass : public Pass {
                HelloWorldPass() : Pass("hello_world") { }
-               virtual void execute(vector<string>, Design*) {
+               void execute(vector<string>, Design*) override {
                        log("Hello World!\n");
                }
        } HelloWorldPass;
@@ -202,6 +202,52 @@ of how to use the Yosys API:
        manual/PRESENTATION_Prog/my_cmd.cc
 
 
+Script Passes
+-------------
+
+The ScriptPass base class can be used to implement passes that just call other passes,
+like a script. Examples for such passes are:
+
+       techlibs/common/prep.cc
+       techlibs/common/synth.cc
+
+In some cases it is easier to implement such a pass as regular pass, for example when
+ScriptPass doesn't provide the type of flow control desired. (But many of the
+script passes in Yosys that don't use ScriptPass simply predate the ScriptPass base
+class.) Examples for such passes are:
+
+       passes/opt/opt.cc
+       passes/proc/proc.cc
+
+Whether they use the ScriptPass base-class or not, a pass should always either
+call other passes without doing any non-trivial work itself, or should implement
+a non-trivial algorithm but not call any other passes. The reason for this is that
+this helps containing complexity in individual passes and simplifies debugging the
+entire system.
+
+Exceptions to this rule should be rare and limited to cases where calling other
+passes is optional and only happens when requested by the user (such as for
+example `techmap -autoproc`), or where it is about commands that are "top-level
+commands" in their own right, not components to be used in regular synthesis
+flows (such as the `bugpoint` command).
+
+A pass that would "naturally" call other passes and also do some work itself
+should be re-written in one of two ways:
+
+1) It could be re-written as script pass with the parts that are not calls
+to other passes factored out into individual new passes. Usually in those
+cases the new sub passes share the same prefix as the top-level script pass.
+
+2) It could be re-written so that it already expects the design in a certain
+state, expecting the calling script to set up this state before calling the
+pass in questions.
+
+Many back-ends are examples for the 2nd approach. For example, `write_aiger`
+does not convert the design into AIG representation, but expects the design
+to be already in this form, and prints an `Unsupported cell type` error
+message otherwise.
+
+
 Notes on the existing codebase
 ------------------------------
 
@@ -373,6 +419,7 @@ Finally run all tests with "make config-{clang,gcc,gcc-4.8}":
        cd ~yosys
        make clean
        make test
+       make ystests
        make vloghtb
        make install
 
@@ -389,6 +436,7 @@ Finally run all tests with "make config-{clang,gcc,gcc-4.8}":
 Release:
 
        - set YOSYS_VER to x.y.z in Makefile
+       - remove "bumpversion" target from Makefile
        - update version string in CHANGELOG
        git commit -am "Yosys x.y.z"
 
@@ -411,6 +459,32 @@ Updating the website:
        git commit -am update
        make push
 
+
+
+Cross-Building for Windows with MXE
+===================================
+
+Check http://mxe.cc/#requirements and install all missing requirements.
+
+As root (or other user with write access to /usr/local/src):
+
+       cd /usr/local/src
+       git clone https://github.com/mxe/mxe.git
+       cd mxe
+
+       make -j$(nproc) MXE_PLUGIN_DIRS="plugins/tcl.tk" \
+                       MXE_TARGETS="i686-w64-mingw32.static" \
+                       gcc tcl readline
+
+Then as regular user in some directory where you build stuff:
+
+       git clone https://github.com/cliffordwolf/yosys.git yosys-win32
+       cd yosys-win32
+       make config-mxe
+       make -j$(nproc) mxebin
+
+
+
 How to add unit test
 ====================