74 lines
2.6 KiB
Python
74 lines
2.6 KiB
Python
#!/usr/bin/env python3
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"""Static decoder for SCJUMP.BIN's progression decision logic. Guarded DFS over its acyclic CFG
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extracts, per decision site, the (chapter_mode, path-condition guards) -> decision value rule.
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Decision->scene resolution is native (u00428010) and out of scope. See
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docs/superpowers/specs/2026-07-07-scjump-decision-decode-design.md.
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(no flag) -> build/scjump-decisions.json + build/scjump-decisions.md
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--verify synthesize a witness per decision, run SCJUMP in vm0, assert emitted 0x62ccf matches"""
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from __future__ import annotations
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import os, sys, json, argparse, collections
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from pathlib import Path
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sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
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import paths
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import sys4load
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from age_opcodes import is_label_argument
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MOV, JMP, JCC = 0x55, 0x8c, 0xa0
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CMP_OPS = {0x5a: "==", 0x5b: "!=", 0x5c: "<", 0x5d: "<=", 0x5e: ">", 0x5f: ">="}
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LOGIC_OPS = {0x56: "and", 0x57: "or"}
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GLOBAL_ATYPES = {3, 4, 5, 6, 8}
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IMM = 0
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FALLTHROUGH = 0xffffffff
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CHAPTER_GLOBAL = 0x3234
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DECISION_GLOBAL = 0x62ccf
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VALID_GLOBAL = 0x0
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END_TARGET = 0x2f78d
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def load_scjump():
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return sys4load.load(paths.scripts()["SCJUMP.BIN"])
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def _code_targets(ins):
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"""Yield the code-target offsets of an instruction (excludes 0xffffffff fallthrough)."""
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for i, (t, v) in enumerate(ins.args):
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if is_label_argument(ins.opcode, i, v) and v != FALLTHROUGH:
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yield v
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def forward_edges_only(scr) -> bool:
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by_off = {ins.offset: ins.offset for ins in scr.instructions}
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for ins in scr.instructions:
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for tgt in _code_targets(ins):
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if tgt in by_off and tgt <= ins.offset:
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return False # a back-edge or self-loop
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return True
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def chapter_dispatch(scr) -> dict:
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"""Scan the top dispatch: eq(dest, 0x3234, N) immediately followed by jcc(dest, block, ...)."""
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out = {}
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code = scr.instructions
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for i, ins in enumerate(code):
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if ins.opcode == 0x5a and len(ins.args) >= 3 \
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and tuple(ins.args[1]) == (3, CHAPTER_GLOBAL) and ins.args[2][0] == IMM:
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n = ins.args[2][1]
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nxt = code[i + 1] if i + 1 < len(code) else None
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if nxt and nxt.opcode == JCC and nxt.args[1][1] != FALLTHROUGH:
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out[n] = nxt.args[1][1]
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return out
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def main(argv=None):
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ap = argparse.ArgumentParser()
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ap.add_argument("--verify", action="store_true") # implemented in Task 4
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args = ap.parse_args(argv)
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scr = load_scjump()
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if args.verify:
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return verify(scr) # Task 4
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return build(scr) # Task 3
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if __name__ == "__main__":
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sys.exit(main())
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