Generates 15 avg_ shader variants by templating from the existing
put_ shaders. Each avg_ shader is identical to its put_ sibling
except the final write does an L2 average with the existing dst:
put_: dst[r,c] = result
avg_: dst[r,c] = (dst[r,c] + result + 1) >> 1
Per H.264 §8.4.2.3.1 (B-slice biprediction): caller pre-loads dst
with the list0 prediction; the avg_ call folds in list1.
Generated via python (avg-shader-gen.py): reads each
v3d_h264_qpel_mcXY.comp, transforms the docstring header + final
write hunk, writes v3d_h264_qpel_avg_mcXY.comp. ~88 lines each;
15 new shader files.
Dispatch reuses the existing dispatch_h264_qpel_diag_qpu helper for
all 15 — same src envelope (10*stride+11 covers any (r±1, c±1)
shift), the L2 step only touches dst. Slightly over-allocates for
the simpler positions (avg_mc20/02/10/30/01/03) but negligible
cost. Eliminates 15 wrappers + 15 src_max bound calculations that
would otherwise duplicate.
CMake foreach loops compile + install 15 new SPV files. ctx grows
15 pipeline pairs. Recipe table flips DAEDALUS_KERNEL_H264_QPEL_AVG_*
from CPU to QPU. Public dispatchers re-defined via the existing
DEFINE_QPEL_DIAG_PUBLIC macro (replaces the CPU-only
DEFINE_QPEL_DISPATCH instantiations).
Verified on hertz:
$ ./build/test_api_h264 | grep "qpel avg" | wc -l
15
$ ./build/test_api_h264 | grep "qpel avg" | grep -c "100.0000%"
15
All 15 PASS 2048/2048 bytes bit-exact via QPU.
QPU coverage for the H.264 8-bit 4:2:0 hot-path pixel kernels:
Layer Coverage
─────────────────────────────────────────────────────────────
IDCT 4x4 luma ✓ cycle 6 (one QPU shader, also handles chroma)
IDCT 8x8 luma ✓ cycle 7
Chroma DC Hadamard CPU only (4 adds + 4 subs; not worth)
Deblock luma_v ✓ cycle 8
Deblock luma_h ✓ PR #28
Deblock chroma_v/h ✓ PR #29
Deblock *_intra CPU only (less common, structurally different)
qpel put_ 15 pos ✓ cycle 9 (mc20) + PRs #30-#33
qpel avg_ 15 pos ✓ THIS PR
The H.264 non-intra-deblock hot path is now FULLY on QPU for any
consumer that initialises daedalus with a QPU-capable context.
claude-noether