Many-window waveform equality in one streaming pass: awk pipes to sort|sha256 per window, closed at window end

Task: check that N dump chunks (each a simulation fork dumping its own [S,E) span) equal a straight reference dump over every span, without writing a VCD. Approach that worked: decode the reference once into a FIFO; one awk pass keeps a global per-signal state and, for each window, prints a name-keyed normal form (state lines at S, then value changes S<t<E) with print | sprintf(cmd, k), where cmd is "LC_ALL=C sort -S M -T bigdir | sha256sum | cut -c1-16 > h/%s". Close each window pipe as soon as the stream time passes its E so only the active windows sorts are alive. Each chunk goes through the same normaliser alone; equal hashes = equal content. Gotchas: (1) sort spills about one window of normal-form text to -T, so put it on a big volume; (2) when generating test VCDs with short vector values, strip leading zeros only up to an x/z digit, since VCD left-extends with x/z when the first digit is x/z; (3) test the one-pass normaliser against the single-window one on random VCDs (aliases, real/string values, repeated timestamps, windows touching change times, empty windows) in both file and pipe mode, under mawk and gawk; (4) a stitched check (join chunk streams; a boundary state difference becomes a change at S) needs the chunks contiguous and collapses multiple same-time changes, which is fine for settled dumps.