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Update pmgen documentation 

Signed-off-by: Clifford Wolf <clifford@clifford.at>
This commit is contained in:
Clifford Wolf 2019-08-15 22:48:13 +02:00
parent eb80d3d43f
commit 969ab9027a
1 changed files with 58 additions and 4 deletions
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62
passes/pmgen/README.md
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@ -118,8 +118,8 @@ write matchers:
connected to any of the given signal bits, plus one if any of the signal connected to any of the given signal bits, plus one if any of the signal
bits is also a primary input or primary output. bits is also a primary input or primary output.
- In `code..endcode` blocks there exist `accept`, `reject`, and `branch` - In `code..endcode` blocks there exist `accept`, `reject`, `branch`, and
statements. `subpattern` statements.
- In `index` statements there is a special `===` operator for the index - In `index` statements there is a special `===` operator for the index
lookup. lookup.
@ -233,7 +233,7 @@ But in some cases it is more natural to utilize the implicit branch statement:
endcode endcode
There is an implicit `code..endcode` block at the end of each (sub)pattern There is an implicit `code..endcode` block at the end of each (sub)pattern
that just accepts everything that gets all the way there. that just rejects.
A `code..finally..endcode` block executes the code after `finally` during A `code..finally..endcode` block executes the code after `finally` during
back-tracking. This is useful for maintaining user data state or printing back-tracking. This is useful for maintaining user data state or printing
@ -243,10 +243,14 @@ debug messages. For example:
code code
stack.push_back(addAB); stack.push_back(addAB);
...
finally finally
stack.pop_back(); stack.pop_back();
endcode endcode
`accept` statements can be used inside the `finally` section, but not
`reject`, `branch`, or `subpattern`.
Declaring a subpattern Declaring a subpattern
---------------------- ----------------------
@ -256,4 +260,54 @@ using a `subpattern(<subpattern_name>);` C statement.
Arguments may be passed to subpattern via state variables. The `subpattern` Arguments may be passed to subpattern via state variables. The `subpattern`
line must be followed by a `arg <arg1> <arg2> ...` line that lists the line must be followed by a `arg <arg1> <arg2> ...` line that lists the
state variables used to pass arguments. Subpatterns allow recursion. state variables used to pass arguments.
state <IdString> foobar_type
state <bool> foobar_state
code foobar_type foobar_state
foobar_state = false;
foobar_type = $add;
subpattern(foo);
foobar_type = $sub;
subpattern(bar);
endcode
subpattern foo
arg foobar_type foobar_state
match addsub
index <IdString> addsub->type === foobar_type
...
endmatch
code
if (foobar_state) {
subpattern(tail);
} else {
foobar_state = true;
subpattern(bar);
}
endcode
subpattern bar
arg foobar_type foobar_state
match addsub
index <IdString> addsub->type === foobar_type
...
endmatch
code
if (foobar_state) {
subpattern(tail);
} else {
foobar_state = true;
subpattern(foo);
}
endcode
subpattern tail
...
Subpatterns cann be called recursively.