Can't Call WinAPI from mCode
Posted: 25 Jul 2020, 12:09
I'm trying to use the function described here to write a machine code function that calls QueryPerformanceCounter() and returns the result. This might seem unnecessary, but, as it turns out, I was able to get better performance by wrapping QueryPerformanceCounter() in my own DLL function and calling that, than by calling the function directly using DllCall(). Anyway, I compiled my DLL with Visual Studio and had the compiler output readable machine code so I could use the function with mCode(). When I compiled a simple function to retrieve a number in memory and called it with mCode(), it worked perfectly. However, when I try to call the mCode() version of my QueryPerformanceCounter() wrapper, I get a blank result. Here's my code:
Also, here are the C++ functions I'm trying to use:
What am I doing wrong?
Code: Select all
#NoEnv
SetBatchLines -1
GetInt64 := mCode("558bec8b4d088b550c8b04118b5411045dc20800", "488b0411c3") ; Retrieves the 64-bit integer at the address + offset specified by the caller
qpc := mCode("558bec83ec0ca10000000033c58945fc8d45f450ff1500000000"
. "8b4dfc8b45f433cd8b55f8e8000000008be55dc3", "4883ec38488b05000000004833c44889442428488d4c2420"
. "ff1500000000488b442420488b4c24284833cce8000000004883c438c3") ; Should call QueryPerformanceCounter() and return the result
VarSetCapacity(num, 32, 0), NumPut(32, num, 7, "Int64")
MsgBox % DllCall(GetInt64, "Ptr", &num, "Ptr", 7, "Int64") ; Correctly displays the number 32
MsgBox % DllCall(qpc, "Int64") ; Returns a blank result
return
mCode(x86_code, x64_code := "", a86_code := "") {
static mCodeFn := (A_PtrSize = 8 ? Func("mCode@x64") : A_IsUnicode ? Func("mCode@x86") : Func("mCode@a86")).Bind(DllCall("GetProcessHeap", "Ptr"))
, hCrypt := DllCall("LoadLibrary", "Str", "Crypt32.dll", "Ptr")
return x86_code == "" ? 0 : mCodeFn.Call(x86_code, x64_code, a86_code)
}
mCode@x86(process_heap, ByRef x86_code, ByRef x64_code, ByRef a86_code) {
If !DllCall("Crypt32\CryptStringToBinary", "Ptr", &x86_code, "uInt", 0, "uInt", 4, "Ptr", 0, "uInt*", length, "Ptr", 0, "Ptr", 0)
return
code_buffer := DllCall("HeapAlloc", "Ptr", process_heap, "uInt", 8, "Ptr", length, "Ptr")
If DllCall("Crypt32\CryptStringToBinary", "Ptr", &x86_code, "uInt", 0, "uInt", 4, "Ptr", code_buffer, "uInt*", length, "Ptr", 0, "Ptr", 0)
return code_buffer
DllCall("HeapFree", "Ptr", process_heap, "uInt", 0, "Ptr", code_buffer)
}
mCode@x64(process_heap, ByRef x86_code, ByRef x64_code, ByRef a86_code) {
code_version := x64_code == "" ? &x86_code : &x64_code
If !DllCall("Crypt32\CryptStringToBinary", "Ptr", code_version, "uInt", 0, "uInt", 4, "Ptr", 0, "uInt*", length, "Ptr", 0, "Ptr", 0)
return
code_buffer := DllCall("HeapAlloc", "Ptr", process_heap, "uInt", 8, "Ptr", length, "Ptr")
DllCall("VirtualProtect", "ptr", code_buffer, "Ptr", length, "uInt", 0x40, "uInt*", old_protection)
If DllCall("Crypt32\CryptStringToBinary", "Ptr", code_version, "uInt", 0, "uInt", 4, "Ptr", code_buffer, "uInt*", length, "Ptr", 0, "Ptr", 0)
return code_buffer
DllCall("HeapFree", "Ptr", process_heap, "uInt", 0, "Ptr", code_buffer)
}
mCode@a86(process_heap, ByRef x86_code, ByRef x64_code, ByRef a86_code) {
code_version := a86_code == "" ? &x86_code : &a86_code
If !DllCall("Crypt32\CryptStringToBinary", "Ptr", code_version, "uInt", 0, "uInt", 4, "Ptr", 0, "uInt*", length, "Ptr", 0, "Ptr", 0)
return
code_buffer := DllCall("HeapAlloc", "Ptr", process_heap, "uInt", 8, "Ptr", length, "Ptr")
If DllCall("Crypt32\CryptStringToBinary", "Ptr", code_version, "uInt", 0, "uInt", 4, "Ptr", code_buffer, "uInt*", length, "Ptr", 0, "Ptr", 0)
return code_buffer
DllCall("HeapFree", "Ptr", process_heap, "uInt", 0, "Ptr", code_buffer)
}Code: Select all
#include <windows.h>
__int64 GetInt64(char* address, intptr_t offset) {
return *(__int64*) (address + offset);
}
__int64 qpc() {
LARGE_INTEGER q;
QueryPerformanceCounter(&q);
return q.QuadPart;
}