forked from opencode.energia.arti.ee/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).
36 lines
1.9 KiB
Plaintext
36 lines
1.9 KiB
Plaintext
THE OUT-CELL IS FILLED FROM object->byte36 -- AND THAT FIELD IS NOT INITIALISED
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BY CREATE.
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A) SOURCE IDENTIFIED (store at 0x6BAAC, breakpoint at 0x3F55D560):
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byte8=1 : obj=0028E050 b36=00290510 STORE src120=00290510 -> out-cell = 00290510
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byte8=3 : obj=003FD7D0 b36=00000000 STORE src120=00000000 -> out-cell = 00000000
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The store's source register A7 IS the object pointer, and it reads
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d@(A7+0x120) = u32(obj, byte 36). So out-cell := object->byte36.
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B) BUT byte36 IS NOT SET BY CREATE. Creating with every w9 value in one run:
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w9=000000 byte8=0 b36=00000000
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w9=000100 byte8=1 b36=00000000
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w9=000200 byte8=2 b36=00000000
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w9=000300 byte8=3 b36=00000000
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w9=000400 byte8=4 b36=00000000
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w9=000500 byte8=5 b36=00000000
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All zero -- yet an earlier run's w9=0x100 object had b36=00290510. So byte36
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is whatever the heap block contained; it is NOT a field the create path sets.
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C) CONSEQUENCE: whether the import gate at 0x6BAF4 is even REACHED depends on
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uninitialised object memory. The "byte8=1 fills the out-cell, byte8=3 does
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not" correlation I reported last turn was an artefact of which allocation
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happened to carry a non-zero byte36 -- not a property of byte8.
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D) WHAT THIS MEANS FOR THE GOAL: to reach AND pass the gate we need a byte8=3
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object whose byte36 happens to be non-zero. Create does not control byte36,
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and a 27-combination sweep of the other create fields (positions 2..10, values
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1/2/3, w9=0x300) produced byte36 != 0 in NO case.
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So the import path depends on an uninitialised field, and the only lever is heap
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layout (what the allocator hands back), not any request parameter. That is
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consistent with a firmware-side uninitialised-field dependency in this path.
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Status unchanged: no client-chosen XIE image; src_base 0; window still the
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stipple; xshow (core X) is the only verified viewer.
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