fix(re): drop dead movw/movt scaffolding in xref.py (ruff F841)

The unused imm4i() helper computed i/imm4/imm8 then returned None; the real
movw/movt decode is inline below it. Removed so ruff F841 passes CI.

Assisted-by: AI

Author: AndrewDemsDS

reverse-engineering/tools/xref.py

@@ -8,8 +8,10 @@
 
 Usage: xref.py <binfile> <base> <target_hex>
 """
+
 import sys
 
+
 def main():
     path, base, target = sys.argv[1], int(sys.argv[2], 16), int(sys.argv[3], 16)
     data = open(path, "rb").read()
@@ -28,28 +30,25 @@ def main():
         # literal pool entry address = base + i ; scan backwards up to 1024+4 bytes
         refs = []
         for j in range(max(0, i - 1050), i, 2):
-            hw = int.from_bytes(data[j:j+2], "little")
+            hw = int.from_bytes(data[j : j + 2], "little")
             # LDR Rt,[PC,#imm] T1: 01001tttiiiiiiii ; addr = (pc&~3)+imm*4, pc=j+4
             if (hw & 0xF800) == 0x4800:
                 imm = hw & 0xFF
                 addr = ((base + j + 4) & ~3) + imm * 4
                 if addr == base + i:
                     refs.append(j)
-        print(f"  pool @ file 0x{i:06x} xip 0x{base+i:08x}  ldr-refs: "
-              + ", ".join(f"file 0x{r:06x} / 0x{base+r:08x}" for r in refs))
+        print(
+            f"  pool @ file 0x{i:06x} xip 0x{base + i:08x}  ldr-refs: "
+            + ", ".join(f"file 0x{r:06x} / 0x{base + r:08x}" for r in refs)
+        )
     # movw/movt search
     lo = target & 0xFFFF
     hi = target >> 16
-    def imm4i(hw):
-        i = (hw >> 10) & 1
-        imm4 = hw & 0xF
-        imm8 = (hw >> 16) & 0xFF if False else None
-        return None
     movts = {}
     movws = {}
     for j in range(0, len(data) - 4, 2):
-        h1 = int.from_bytes(data[j:j+2], "little")
-        h2 = int.from_bytes(data[j+2:j+4], "little")
+        h1 = int.from_bytes(data[j : j + 2], "little")
+        h2 = int.from_bytes(data[j + 2 : j + 4], "little")
         # MOVW: 11110 i 100100 imm4 | 0 imm3 Rd imm8  => 0xF240 pattern
         # MOVT: 11110 i 101100 imm4 | 0 imm3 Rd imm8  => 0xF2C0
         if (h1 & 0xFBF0) in (0xF240, 0xF2C0):
@@ -67,7 +66,10 @@ def imm4i(hw):
         for tj in movts.get(rd, []):
             for wj in locs:
                 if 0 < tj - wj <= 24:
-                    print(f"  movw/movt r{rd} @ file 0x{wj:06x} / xip 0x{base+wj:08x}")
+                    print(
+                        f"  movw/movt r{rd} @ file 0x{wj:06x} / xip 0x{base + wj:08x}"
+                    )
+
 
 if __name__ == "__main__":
     main()