forked from arti/vt1200
arti
d8d54bb990
The XIE path now runs end to end: XieCreateImage -> XieCreatePhoto ->
XiePutTile -> XieExport(photomap -> depth-1 pixmap) -> XCopyArea(pixmap ->
window), and the client's tile appears on screen at the client's own window
position, pixel-exact.
TWO FAULTS BEHIND THE LONG DEAD END
1. Device model (harness/mame/vt1200.cpp, opt-in VT1200_ACCEL=1). The
accelerator's output port 0x5600200 returns the pixel stream the firmware
pushed into the FIFO -- the firmware then stores it into the drawable itself
(file 0x125528: MOVE *B6,*B1 ; ADDK 0x10,B1). The FIFO read pointer was
never reset between transfers, so consecutive exports read stale words and
the same fill produced 759 then 516 set pixels. Reset m_fifo_in/out on the
data-register write; the export is now deterministic.
2. Measurement, not the device.
- dwt/screenshot.py without --real reads 1024x1024 at a 128-byte row stride,
but the VR319 default programs 1280x1024 at a 2048-bit (256-byte) pitch.
That is the "shifted" picture; --real is the correct read.
- The earlier "0 differing bytes over 128 KiB" VRAM comparison stepped peek
by 1024 *bit* addresses, so it scanned rows 0..63 only -- never the window
at rows 200..263. Over the real raster the white/black diff is 576 bytes
spanning exactly those rows.
- New instrument: decclient does a server-side XGetImage readback of the
pixmap and window and counts set pixels. That separated "the server never
drew it" from "the framebuffer view is wrong".
EVIDENCE (reproduced twice, the second time from a fresh machine)
no export vs 0xFF : 4096 / 4096 pixels differ
no export vs 0x00 : 0 / 4096 (the window background is black)
0xFF vs 0x00 : 4096 / 4096
0xAA vs 0x0F : 2048 / 4096 (the two stripe phases)
Tile byte 0xAA reproduces as 1-pixel vertical stripes, 0x0F as 4-pixel, with
no shear -- so the placement is right and the pixels are the client's.
Contents: xie/ holds DEC XIE 2.3 headers, 84 man pages and complete
client+server source; a libXie.a and decclient built from DEC's own code; the
XIE probes; and evidence/ with every measurement, including explicit
retractions of the earlier wrong readings (VRAM_IDENTICAL_FOR_BOTH_FILLS and
friends). xie/evidence/XIE_IMAGE_DISPLAYED.md is the report; frames are in
xie/evidence/png/.
The accelerator model stays opt-in: it answers the status poll and relays the
pixel stream, but performs no compositing, so it is a stand-in and the verified
default configuration is unchanged (a no-env run still parks in the level-0
diagnostics menu at PC=3FDCE400).
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40 lines
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WITH THE COMPRESSION FIELD CORRECTED, THE RENDERER ADVANCES PAST BOTH ITS FIRST
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CHECKS -- AND STILL FAILS LATER.
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A) ROOT CAUSE (measured end to end)
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render setup 0x1B256: rp byte 198 <- element byte 4 (element = 0x3FD590)
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live: W256 a5=003FD590 val=55 rp=00291550
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RD198 rp=00291550 b198=55
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element byte 4 is 0x55 = heap fill, i.e. NEVER INITIALISED, and the firmware
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copies it verbatim into renderptr->compression_scheme.
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B) FORCING THE DEFINED VALUE (labelled debug poke: element.byte4 = 0 = XieK_PCM)
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at the copy site 0x1B256:
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FORCED b4=0 rp=00291550
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CHK_610 val=00911050 ; renderptr->src_base is NON-ZERO
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PAST_610_OK ; the src_base check passes
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So with compression corrected the two DDX_RENDER gates
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"unsupported compression scheme" and "renderptr->src_base == NULL"
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both pass. This confirms the diagnosis: the first failure really was the
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uninitialised compression field.
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C) STILL FAILING AFTERWARDS
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Export still returns BadValue, and the third documented DDX string
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"DDX_RENDER: error allocating tmpudp or smiconvert to dst_photo"
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(file 0x3722E, referenced at file 0x37126) does NOT fire either.
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So a further BadValue is raised after both gates, on a path not covered by
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the three strings the firmware carries.
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D) WHAT IS NOW PROVEN
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* The client, the request, the transport, the photomap, the drawable, the GC,
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the depth, the geometry and the imported data are all correct (unchanged
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across ~40 turns of measurement).
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* The export's first failure is a server-side uninitialised field
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(band element byte 4), copied into the render params as the compression
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scheme and rejected by DDX_RENDER's first validation.
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* Correcting that field moves the renderer past both of its first gates.
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STATUS. NO client-chosen XIE image has been displayed. Window unchanged;
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white vs black captures differ only by Terminal Manager figures and cursor.
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xshow (core X) remains the only viewer that has shown an image.
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