It adds `DriveBit`, `DriveChunk` and `DriveSpec` types which are similar
to `SigBit`, `SigChunk` and `SigSpec` but can also directly represent
cell ports, undriven bits and multiple drivers. For indexing an RTLIL
module and for querying signal drivers it comes with a `DriverMap` type
which is somewhat similar to a `SigMap` but is guaranteed to produce
signal drivers as returned representatives.
A `DriverMap` can also optionally preserve connections via intermediate
wires (e.g. querying the driver of a cell input port will return a
connected intermediate wire, querying the driver of that wire will
return the cell output port that's driving the wire).
This is already supported by `SigSpec` and since both `SigChunk` and
`SigSpec` implement `extract` which is the multi-bit variant of this,
there is no good reason for `SigChunk` to not support
`SigBit operator[](int offset)`.
When implementing custom log_... functions or custom overloads for the
core log functions like log_signal it is necessary to return `char *`
that are valid long enough.
The log_... functions implemented in log.cc use either `log_id_cache` or
`string_buf` which both are cleared on log_pop.
This commit adds a public `log_str` function which stores its argument
in the `log_id_cache` and returns the stored copy, such that custom
log functions outside of log.cc can also create strings that remain
valid until the next `log_pop`.
This adds a generic non-recursive implementation of Tarjan's linear time
SCC algorithm that produces components in topological order. It can be
instantiated to work directly on any graph representation for which the
enumerate_nodes and enumerate_successors interface can be implemented.
Only the `B` input (the shift amount) can be marked as signed on a
`$shiftx` cell. Adapt the helper accordingly and prevent it from
creating invalid RTLIL when called with `is_signed` set. Previously
it would mark both `A` and `B` as signed.
If a `RTLIL::Const` is composed of multiple strings, such as when using a ternary expression to select between two strings of different lengths, zero padding for the strings needs to be maintained.
Only leading (and trailing) null characters should be dropped from the decoded string, rather than all null characters.
