ROADMAP P5. The loader moved in session 21 and the frame clock in 22; the ring
producer was the last policy living outside the machine. src/player/ring.i does
`aligned` placement, the descriptor ring, a prefill, 51.2's slack rule and a
seek, and the host keeps only the transport.
It needed a container change. `aligned` asks whether the next record fits
before the end of the ring -- a length asked BEFORE the record is fetched -- and
every reader in this tree answered that by walking the frame stream, which is
exactly what a player streaming off a disc cannot do. DLX4 carries nframes u16
record lengths in the scene header. Frame payloads are byte-identical to the
DLX3 encode, so no fitted constant moves; the scene header goes 5,920 to 6,164 B.
The producer reproduces the host's tiling exactly: 18 wraps, 14.7 KB mean hole,
pixel-exact, a third independent implementation of the same policy.
What it exposed is bigger than the item. A channel only moves bytes while it has
a request and only the CPU can issue one, so the disc stands still between
records by an amount the PLAYER sets, not the medium -- and no host-filled run
could see it. At 488 KB/s in a 256 KB ring a one-deep request queue gives away
6.8% of the pipe and underruns 59 of 120 frames; two-deep gives away 3.4% and
underruns none. The container's whole surplus over the wire is 8.7%, so the
player's own loop was spending most of the slack a branch point saves up.
Prefill is the weaker lever: six records of it still leaves 24 underruns.
Three silent bugs are recorded in FINDINGS 55.7 -- all produced wrong pixels or
a desync rather than a fault -- plus a rig one: MAME renders a screen line by
line, so snapshotting the frame the decoder finished in captures a tear that
reads exactly like a decoder bug.
check.sh gains the machine-owned ring and a seek with the decode after it.
decode.bin is unchanged at 1,296 B and a host-filled run executes none of the
new code, so every FINDINGS 49/51 figure stands. ALL GREEN before and after.
Claude-Session: https://claude.ai/code/session_01194oWYW8DQXK1SZ2DnChW6
src/player/load.i expands both codebooks to word-per-pixel form and packs the
palette to GGGGGRRRRRBBBBBI out of the RAW container header, byte-exact against
tools/bench/dlxload.py on both CPU cores. The palette half is gated on words
read back out of the palette registers at $E82000, so "the words reached the
hardware" is part of what passes. ROADMAP P1 is done; P2's encoder half (a
reserved black entry, 23.4) is not, and is a re-encode rather than an edit.
A scene change costs 18.96 ms of 68000 time, 22.8% of one 12 fps frame; boot
costs 24.70 ms. The scratch tables describe the CRTC, not the scene, so
pal_tables is a separate entry point built once at boot -- 5.29 ms off every
scene change.
The one that moves something: the scene header is 5,920 B that no rate table in
this tree included, because it belongs to no frame record. In FINDINGS 51.3's
currency it is divided by the surplus pipe - wire, so it is hypersensitive:
138 ms of extra refill climb at 488 KB/s and 1.099 s at 451.4 KB/s, for the
same bytes. tools/analysis/22_scene_load.py prices it across explicit rates.
Recorded as open: the two CPU cores agree to <3% on every stage but the table
build, where they differ by 16.4%. px68k's C68K charges a flat 50 clocks for
MULU/MULS (c68kmacro.h:1869) where the 68000 charges 38+2n, which explains
4,608 of the 8,703 clock gap. 4,095 clocks are unexplained. Nothing else in
src/player/ multiplies, so no figure in FINDINGS 24-52 is affected.
decode.s and stream.s are untouched; decode.bin is still 1,296 B at the same
MD5. check.sh gains a stage that gates byte-exactness on both cores and
deliberately does not gate the cycle counts -- MAME's clock is 1/55.46 s and a
wall timing would make the green light host-sensitive.
Claude-Session: https://claude.ai/code/session_01194oWYW8DQXK1SZ2DnChW6
prosolis