support B2 patches on BB

2024-05-05 10:51:13 -07:00
parent 27bbb2c7e4
commit 70413668d8
4 changed files with 83 additions and 12 deletions
@@ -0,0 +1,29 @@
+start:
+  push    ebx
+  jmp     get_patch_data_ptr
+get_patch_data_ptr_ret:
+  pop     ebx                   # ebx = patch header
+
+apply_next_patch:
+  cmp     dword [ebx + 4], 0
+  jne     copy_code_and_apply_again
+  pop     ebx
+  mov     eax, 1
+  ret
+
+copy_code_and_apply_again:
+  xor     ecx, ecx              # ecx = offset
+  mov     edx, [ebx]            # edx = dest addr
+copy_next_byte:
+  mov     al, [ebx + ecx + 8]   # copy one byte to dest
+  mov     [edx + ecx], al
+  inc     ecx                   # offset++
+  cmp     [ebx + 4], ecx        # check if all bytes have been copied
+  jne     copy_next_byte
+
+  lea     ebx, [ebx + ecx + 8]  # advance to next block
+  jmp     apply_next_patch
+
+get_patch_data_ptr:
+  call    get_patch_data_ptr_ret
+first_patch_header: