Add source code for exchange_u32

XboxDev · Feb 11, 2022 · 3afc220 · 3afc220
1 parent fb04281
commit 3afc220
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Showing 3 changed files with 25 additions and 1 deletion.
diff --git a/Trace.py b/Trace.py
@@ -57,7 +57,11 @@ def free_code():
 def _exchangeU32Call(xbox, address, value):
   global exchange_u32_addr
   if exchange_u32_addr is None:
-    exchange_u32_addr = _loadBinary(xbox, bytes([0xFA, 0x8B, 0x44, 0x24, 0x04, 0x8B, 0x54, 0x24, 0x08, 0x87, 0x02, 0xFB, 0xC2, 0x08, 0x00]))
+
+    with open("exchange_u32", "rb") as infile:
+      data = infile.read()
+
+    exchange_u32_addr = _loadBinary(xbox, data)
     print("exchange_u32 installed at 0x%08X" % exchange_u32_addr)
   return xbox.call(exchange_u32_addr, struct.pack("<LL", value, address))['eax']
 

diff --git a/exchange_u32 b/exchange_u32
diff --git a/exchange_u32.asm b/exchange_u32.asm
@@ -0,0 +1,20 @@
+; Construct binary using `nasm exchange_u32.asm`
+
+bits 32
+
+exchange_u32:
+
+; Avoid any other CPU stuff overwriting stuff in this risky section
+cli
+
+; value
+mov eax, dword [esp+4]
+
+; address
+mov edx, dword [esp+8]
+
+xchg dword [EDX],EAX
+
+sti
+
+ret 0x8