#!/usr/bin/env python3
"""Is the C68K harness's decode pixel-exact against the reference decoder?

    python3 tools/bench/c68k/verify_c68k.py <in.dlx> --nframes N

This is the licence for every cycle number the harness prints. The harness
rebuilds px68k's memory model from scratch -- byte-swapped RAM, GVRAM word
writes that discard the high byte, a hand-rolled 24-bit map -- and any of that
being subtly wrong would still produce plausible-looking cycle counts. It could
not produce a pixel-exact 80-frame temporal recursion.

Unlike tools/bench/verify_decode.py this compares palette INDICES, not rendered
RGB: the harness dumps the low byte of each GVRAM word directly, so there is no
palette round-trip to model and no snapshot geometry to unpick.
"""
import argparse, sys
sys.path.insert(0, "tools/encoder")
import numpy as np
from dlx import DLX

ap = argparse.ArgumentParser()
ap.add_argument("container")
ap.add_argument("--dump", default="tmp/c68k_screen.bin")
ap.add_argument("--nframes", type=int, default=None)
a = ap.parse_args()

d = DLX(a.container)
NF = a.nframes if a.nframes is not None else d.nframes
if NF > d.nframes:
    sys.exit(f"--nframes {NF} exceeds the container's {d.nframes}")

canvas = np.zeros((d.H, d.W), np.uint8)
for f in range(NF):
    d.paint(canvas, f)

got = np.fromfile(a.dump, np.uint8)
if got.size != d.H * d.W:
    sys.exit(f"FAIL 1. dump is {got.size} B, expected {d.H*d.W}")
got = got.reshape(d.H, d.W)

if not np.array_equal(got, canvas):
    bad = got != canvas
    by, bx = np.where(bad)
    blocks = sorted(set(zip((by // 4).tolist(), (bx // 4).tolist())))
    sys.exit(f"FAIL 2. frame {NF-1} not pixel-exact under C68K: {bad.sum()} px in "
             f"{len(blocks)} blocks differ; first block "
             f"(by={blocks[0][0]}, bx={blocks[0][1]})")

print(f"OK  {NF} frames decoded on px68k's C68K core, final frame pixel-exact "
      f"against tools/encoder/dlx.py")
print(f"    {d.W}x{d.H}, {d.nb} blocks/frame, k1={d.k1} k4={d.k4}; the memory "
      f"model (byte-swapped RAM, high-byte-discarding GVRAM) is therefore right")