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 ( \( )  /__\  / __)(  )  / __)(  _  )( \( )
  )  (  /(__)\( (__  )(__( (__  )(_)(  )  (
 (_)\_)(__)(__)\___)(____)\___)(_____)(_)\_)

The History of Hacking  ·  May 31 – June 2, 2026  ·  Carolina Beach, NC

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  • docs/v322_new.md src/sbbs3/sexyz.c

    From Rob Swindell (on Debian Linux)@VERT to Git commit to main/sbbs/master on Fri Jul 24 23:28:15 2026
    https://gitlab.synchro.net/main/sbbs/-/commit/aaf394a0d833acd89a64d3a9
    Modified Files:
    docs/v322_new.md src/sbbs3/sexyz.c
    Log Message:
    sexyz: keep the transmit window >= 4x the block size, like lsz (#1197)

    sexyz's -w set only the ZMODEM transmit window and left the block size independent (from -2/-4/-8, default 1 KB), so a window at or below the
    block size was configurable -- and it stalled the transfer to roughly one window per second. lsz and Forsberg sz never allow this: when -w is
    given they force the block down to a quarter of the window
    (blkopt = Txwspac = Txwindow/4), guaranteeing window >= 4*block so the ack-every-quarter-window scheme always has several blocks in flight.

    Do the same after argument parsing, so -8 -w8192 and -w8192 -8 both
    resolve the same way: floor the window to 256, round to a multiple of 64,
    and reduce max_block_size to window/4 when it exceeds it (and the start block_size with it). A one-line notice reports the reduction.

    Effect: the formerly-hanging window<=block configurations now complete --
    -8 -w8192 reduces the block to 2048 and transfers, -4 -w4096 to 1024,
    and so on -- while windows that already left four blocks of headroom
    (-w32768 and up with -8) are untouched and unchanged (4.75 and 4.88 MB/s
    here, streaming still 11.3). This also makes the divide-by-zero guarded
    in 04b47329aa unreachable by configuration, since window/block/4 is now
    always >= 1.

    This does not make sexyz's windowed throughput competitive with lsz --
    at the same block and window sexyz is still many times slower, and very
    small windows (which force tiny blocks) remain slow with occasional
    one-second stalls. That is the separate sexyz windowed-send overhead
    tracked in #1195; this change is only about not permitting the degenerate window<=block configuration that lsz forbids by construction.

    sexyz.c version 3.3 -> 3.4. No zmodem.c change, so SyncTERM is
    unaffected (it never sets a transmit window anyway).

    Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

    ---
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