What sort of string-like behavior would one want on a bit-string? Seems like array would be the better fit to me...
On Wed, Dec 18, 2024 at 9:03 AM pogo 59 via Dwarf-discuss < dwarf-discuss@lists.dwarfstd.org> wrote: > My first thought would be that DW_TAG_string_type with a one-bit base > type, but it's not clear that the other attributes would be interpreted in > a way that correctly navigated the bit string. You could try using > DW_TAG_packed_type pointing to a DW_TAG_string_type, in the hopes that > consumers would figure out that it was a "packed" string of bits, and that > the element stride and sizes should be bits. I believe Pascal would > describe "packed array of boolean" that way, or however Pascal spells that > type. > > If that doesn't pan out, DW_TAG_array_type can certainly describe > bit-sized elements, with DW_AT_bit_stride of 1. This might not get you > string-like semantics in the consumer, but it would describe the data > accurately. > --paulr > > On Wed, Dec 18, 2024 at 8:50 AM Thomas David Rivers via Dwarf-discuss < > dwarf-discuss@lists.dwarfstd.org> wrote: > >> >> PL/I has the concept of a "string", which can be a fixed-length >> (possibly not known at compile time), or a fixed size with a 4-byte or >> 2-byte >> runtime length prefix, or, depending on the consituents, a NULL >> (zero-byte) >> terminated string. >> >> For "character-like" strings, the constituents can be 1-byte, 2-byte, >> 4-byte strings, or UTF-8 values. (e.g. strings of characters, or strings >> of UTF-8 values, or strings of 4-byte unicode values.) >> >> All of these seem to be straightforwardly handled by DWARF-5. >> >> However, PL/I also has a "BIT string", which is a left-adjusted string >> of bits, either of a fixed length (# of bits) or of a fixed size >> with a either a 2-byte or 4-byte length prefix. Of course, there isn't >> a NULL-terminated variant of this string, because a zero-bit is part of >> the data. The sizes may not be known at compile time. >> >> I've gone thru the DWARF-5 standard a few times, but can't seem to >> envision a straight-forward way to represent this. >> >> Furthermore, an un-prefixed bit-string doesn't necessarily begin >> on a byte boundary, and, depending on the environment, needs to >> be represented as a bit-offset which may be composed (even at runtime) >> of (byte-location + bit-offset-in-byte). >> >> Any suggestions on how to represent this in DWARF (5 or later) would >> be appreciated! Perhaps it's just something obvious I'm overlooking?? >> >> - Many Thanks! - >> - Dave Rivers >> >> -- >> riv...@dignus.com >> -- >> Dwarf-discuss mailing list >> Dwarf-discuss@lists.dwarfstd.org >> https://lists.dwarfstd.org/mailman/listinfo/dwarf-discuss >> > -- > Dwarf-discuss mailing list > Dwarf-discuss@lists.dwarfstd.org > https://lists.dwarfstd.org/mailman/listinfo/dwarf-discuss >
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