The option is serialized to RTLIL as `_` (to match Python's option with
the same symbol), and sets the `group` flag. This flag inserts an `_`
symbol between each group of 3 digits (for decimal) or four digits (for
binary, hex, and octal).
The option is serialized to RTLIL as `#` (to match Python's and Rust's
option with the same symbol), and sets the `show_base` flag. Because
the flag is called `show_base` and not e.g. `alternate_format` (which
is what Python and Rust call it), in addition to the prefixes `0x`,
`0X`, `0o`, `0b`, the RTLIL option also prints the `0d` prefix.
This format type is used to print an Unicode character (code point) as
its UTF-8 serialization. To this end, two UTF-8 decoders (one for fmt,
one for cxxrtl) are added for rendering. When converted to a Verilog
format specifier, `UNICHAR` degrades to `%c` with the low 7 bits of
the code point, which has equivalent behavior for inputs not exceeding
ASCII. (SystemVerilog leaves source and display encodings completely
undefined.)
Before this commit, the existing alignments were `LEFT` and `RIGHT`,
which added the `padding` character to the right and left just before
finishing formatting. However, if `padding == '0'` and the alignment is
to the right, then the padding character (digit zero) was added after
the sign, if one is present.
After this commit, the special case for `padding == '0'` is removed,
and the new justification `NUMERIC` adds the padding character like
the justification `RIGHT`, except after the sign, if one is present.
(Space, for the `SPACE_MINUS` sign mode, counts as the sign.)
The first two were already supported with the `plus` boolean flag.
The third one is a new specifier, which is allocated the ` ` character.
In addition, `MINUS` is now allocated the `-` character, but old format
where there is no `+`, `-`, or `-` in the respective position is also
accepted for compatibility.
Before this commit, the `STRING` variant inserted a literal string;
the `CHARACTER` variant inserted a string. This commit renames them
to `LITERAL` and `STRING` respectively.
Mostly memory_libmap arg checks; puts the checks into an else block on the `if (help_mode)` check to avoid cases like `synth_ice40` listing `-no-auto-huge [-no-auto-huge]`.
Also fix `map_iopad` section being empty in `synth_fabulous`.
`config-clang` is the default, and doesn't need to be run first. Previous instructions were ambiguous about that point.
Add note on using a different `CXX`.