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).
33 lines
1.5 KiB
Plaintext
33 lines
1.5 KiB
Plaintext
THE ENGINE'S OUTPUT GOES TO MAIN RAM, NOT VRAM -- AND OUR PIXELS DO NOT LAND.
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Instrumented the read-back loop at file 0x125528 during a completing export:
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0x125528 MOVE *B6,*B1 ; engine output port 0x5600200 -> *B1
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0x12552A ADDK 0x10,B1 ; advance one word
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0x12552C DSJS A11,0x125528
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Measured destination pointer:
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DST b1=004FE790 b2=3FB2ACF0 a6=00000000
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DST b1=004FE7A0 ...
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distinct b1: first=004FE790 last=004FE980
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inside VRAM (0x04000000..0x1fffffff): FALSE
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So B1 is a MAIN RAM buffer (0x004FE790..0x004FE980, ~0x200 words), i.e. the
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engine's result is staged in RAM and something else is expected to move it to the
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frame buffer. The 384 reads of 0x5600200 come from exactly this loop (384 == the
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a1 argument seen at the routine entry).
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CHECKED: after a white export, the staging buffer does NOT contain 0xFFFF --
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0x004FE790 holds pointer-like garbage instead. So either the read-back returns
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the wrong thing, or this path is not the one that carries the tile.
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STATE
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* export completes without error (opt-in VT1200_ACCEL model);
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* source pixels do reach the accelerator FIFO (0xFFFF / 0x0000 verified);
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* the engine's output is staged to main RAM at 0x004FE790 (destination located);
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* the staged data is not our tile, and nothing writes the tile to VRAM;
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* NO client-chosen XIE image has ever been displayed; white vs black captures
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differ only by Terminal Manager figures and cursor;
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* model opt-in; default configuration unchanged;
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* xshow (core X) is still the only viewer that has shown an image.
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